Some events can cast long shadows. The UK is still talking about the storm of 1987 (‘the worst night since the Blitz’), the winter of 1963, the storm floods of 1953, the London smog of 1952, the Great Storm of 26 November 1703. Other countries have their own stories. But one event in particular still haunts the UK. Discussions are still continuing on what exactly happened: was it a storm surge, a tsunami?
This is the story of the Bristol flood of 1607.
(This post is expanded and updated from one previously published in 2017.)
Woodcut of the disaster, showing the church of Nash surrounded by water.
I have seen fish and men hanging from trees,
while the cow, sheep, and horse swam in the sea.
Where wagons used to roll, there the skiff flies along with sails unfurled,
and goes and returns by unaccustomed routes.
It was one of those days. Living on the coastal flood plain is always chancy. You are only as secure as your flood defences, and on this day, those defences weren’t good enough. The sea broke through, and flooded the low-lying levels around the Bristol channel, even encircling Glastonbury. As one commentator later wrote, Men that were rich getting out of bed in the morning, were poor before noon the same day. Possessions, land, buildings, they were gone. For others it was much worse. The water came without warning, submerging farms and towns. Perhaps 2000 people died, unable to flee from the floods. More than 400 years later, this still ranks as the UK’s worst flood disaster.
Even without the flood, these were memorable times. The controversial King James was on the English throne. Guy Fawkes had just tried to blow up parliament, which for unfathomable reasons is still celebrated in the UK, on the 5th of November. The King James bible was being written, and Shakespeare performed in London as one of the King’s Men, his plays already famous. In these exciting times, the news from the west country still caused upset.
Date
The date of the disaster can seem as confused as the events themselves. Some records give it as January 20, other as January 30, and the year is given as 1606 or 1607. A few people have suggested that there must have been more than one event. But the explanation for the confusion is prosaic. After 16b centuries, the calendar had slowly gone out of sync with the seasons and by this time the difference had become notable. To re-align the year with the seasons, the catholic church had initiated a new calendar, with fewer leap days and shifted by ten days. The Gregorian calender replaced the old Julian one, and was a clear improvement. But it suffered from one major draw-back: it was catholic, at a time of strong protestant movements in northern Europe. Many were slow to adopt the new enemy calendar. England in particular had held off, even in those days already being wary of new-fangled continental innovations. So Bristol still used the Julian calendar – for them the date was Jan 20. But many people in London, perhaps more progressive and certainly more international in their outlook, had started to use the Gregorian calendar in use in France and Spain – so here the date was commonly (but not invariably) listed as January 30.
How about the year? That seems harder to get wrong! But in the Middle Ages, the year did not start in January, but at Easter or the onset of spring. This had ancient roots. The Jewish calendar, the oldest for which we have written records, originally started each year in spring. (It changed later to start in the autumn, probably during to the Babylonian era as Mesopotamia had always used this system. The Jewish scriptures use both systems, some predating and others postdating the change-over.) The equinoxes are convenient, by the way, because the position of the Sun on the sky changes rapidly at these times, so the precise date can be measured easily. They are also more important than the solstices for agriculture. During the Middle Ages, the start of the year in the UK was taken as March 25, ‘Lady Day’, nine months before Christmas. The Gregorian calendar confirmed January 1 as the start of the year. Some regions which had not accepted the new calendar did accept the new beginning. So late January was 1607 according to the new system, but still in the previous year, 1606, according to the old one. Any newspaper called ‘The Times’ would have had to specify which times.
As a sign of the old times, the tax year in the UK still runs from April 5. When the Gregorian calendar was adopted, the shift had become 11 days and so March 25 became April 5. The UK tax authorities noted the change in day but still haven’t noted the change in the star of the year. )
Events
The events happened around the Bristol channel, the sea arm which separates the southwest of England from Wales and forms a funnel aimed at the heart of England, the Cotswolds. This had been one of the invasion routes considered by the Spanish armada. The funnel narrows until it becomes the Severn estuary. The funnel shape, and the fact that it has just the right length to act as a resonator, causes an extreme tidal range which is one of the largest in the world. Beyond Bristol, the estuary becomes the river Severn, which is the longest river in the UK (Bristol itself is on a different river, the Avon). The Severn is famous for its bore, a solitary wave running upstream with the tide. On both sides of the Bristol channel are extensive low-lying areas. On the north side are the low-lying area around Cardiff and Swansea in Wales. On the south side are the Somerset Levels, an area still prone to river flooding today.
Bathymetry and topography of the Bristol Channel and the Severn Estuary
A number of towns had sprung up around the channel, some Roman in origin (Cardiff), some Viking (Swansea), some medieval trading centres (Bristol). The flood plains themselves were extensively farmed. There were sea defences, but they were not in as good a shape as they should have been. This was in part because of the dissolution of the monasteries: these had been responsible for some of the upkeep, and although the new owners were legally required to take this on, it was expensive and maintenance was falling behind. The flood plains were a sitting duck.
The period between 1560 and 1630 was a cold phase in the Little Ice Age. This phase is known as the Grindelwald Fluctuation (named after a Swiss glacier). The years after 1600 were especially chilly, sometimes attributed to the eruption of Huaynaputina. Storms were more frequent than they are nowadays, with perhaps the storm tracks running further south. On this day, in the early morning of January 30, the sea rose, and kept rising. By 9 am the dikes crumbled or were overtopped. The sea did not quietly accept its boundaries – water is a jealous neighbour.
Appledore is an example of a seafront town affected by the flood. It is located on the tidal river Taw, just downstream from Barnstaple, the first place along the Bristol Channel to feel the incoming surge. As the waves came in, houses were swept away. It appears the entire sea front was destroyed. The houses along the shore were not rebuild for a century afterwards – the memory ran deep. Appledore and Barnstaple form a low-lying inlet in a hilly landscape. The flood moved up the river and flooded the inlet. The uphill areas a bit away from the river stayed dry. However, Barnstaple was hit hard; a few hundred people reportedly perished here.
The river front at Appledore
The author and barrister Walter Yonge wrote in his diaries about the events at Barnstaple and elsewhere of that morning. That in itself was already notable: the preceding two entries were the London plague of 1604 and the 5 Nov 1605 attack on the government! He wrote briefly:
The 20th of Jan 1606-7, by reason of a great tempest, the sea brake in at divers places on the north side of this country, as at Barnstaple, where was much hurt done. At Bridgwater two villages near thereabouts and one market town overflown, and report of 500 persons drowned, besides many sheep, and other cattle. At Bristol it flowed so high that divers packs, which were brought thither against Paul’s fair, standing together in a common hall of the city, for such purposes, stood three foot deep in water. The water at Barnstaple was said by another person (Fuller) to have been 1.5 to 2 meters higher than ever known before.
Around Cardiff, on the Welsh side of the Bristol channel, many low-lying areas were flooded and the water reached into the city. The nearby flooded areas were sparsely inhabited at the time (nowadays they are densely packed suburbs). The main church in Cardiff, St Mary’s Parish Church, became undermined by the water. Over the following years, the church was slowly abandoned in favour of a sturdier one, although it remained in use until after 1700. Some populated areas further east were wiped out: here, only the churches, complete with flood marks, remained.
The likely extent of the 1607 flooding in the Somerset levels. http://westoverward.co.uk/flooding/
The flood came in furthest in the Somerset Levels, a flood plain protected by less than solid embankments. The surge traveled up the rivers, reaching the centre of Bristol and flooding the area around the river Severn as far as Gloucester, the very area where nowadays surfers tackle the famous Severn bore.
The Great Flood memorial in Kingston Seymour church, Somerset
An anonymous manuscript from Bristol writes about the flooding: January 20th: in the morning being Tuesday at high water there arose such a high flood that the sea drove over the banks and drowned all the marsh country in Wales and on the English coasts. It drowned the cattle and carried away the corn and hay, and the people to save themselves climbed upon the tops of houses and trees, and it did carry away many houses and trees and many people were drowned the flood came on so fast. It came so fast & high at Henbury [a low-lying parish] that the waters continued a long time a fathom deep that the people were obliged to abide on the trees two or three days. And this mayor Mr Barber hearing of their distress commanded cock-boats to be hauled thither to fetch the people that were on trees that they might not perish with cold and hunger. And in the city of Bristol all the lower part were drowned about 4 or 5 foot so that a boat of about five tons came up to Saint Nicholas crowd door [the crypt]. The boatman put his boathook against the lower step and thrust off his boat again. The Waters were up in Saint Stephen’s, Saint Thomas and Temple churches halfway up the seats. And the Bridge arches were stopped so that the water buoyed up higher towards Temple and Redcliff sides than in any other parts which at the return it brought down the river great trees but did not hurt the Bridge. The merchants received great losses in their storehouses and cellars by it. (from a 2021 paper)
Based on the flood marks on the churches, the water reached over 7 meter above AOD (Ordnance Datum) on the Welsh side, and over 7.5 meter on the Somerset Levels. This is actually not as high as might have been expected, as this would have been about the peak tidal level and the surge must have been well above that. The suspicion has been raised that the land has sunk by 1-2 meters since 1600, due to the improved drainage. Others argue that the tidal range has increased but there is no evidence for this and it seems too speculative. Perhaps the people putting up the markers were conservative in their estimates.
Th St Mary the Virgin church in Nash, depicted in the woodcut at the top of the post.
Comparing the woodcut of the flood with the modern view of the same 12th century church (Nash, Newport) gives an indication how deep the flood was. However, one should allow for some artistic license of the maker of the woodcut. The flood marker is near the door, ‘only’ about 1.5 meter above ground level, but it is small and indistinct and it is not clear that this actually is for the 1607 flood.
Cause of the 1607 disaster
Tsunami
The 1607 flood made the news once more when Haslett and Bryatt proposed that it had been caused by a tsunami. The disasters in Indonesia, Sri Lanka, and Japan over the past two decades have shown the devastation a tsunami can cause: the power of water is immense, and in the cities that were affected by tsunamis, almost nothing was left standing. This video is one of the scariest of the 2011 Japan tsunamis, starting with people horrified by a distant disaster unfold and ending with blind panic.
The idea that such a tsunami could happen, and had happened, in the UK was a sobering thought. The evidence for this came from a particular description of what happened, in a document entitled ‘Gods warning to his people of England’.
Then they might see & perceive a far of as it were in the Element, huge and mighty Hilles of water, tumbling one over another, in such sort as if the greatest mountaines in the world, has over-whelmed the lowe Valeys or Earthy grounds. Sometimes it so dazled the eyes of many of the Spectators, that they immagined it had bin some fogge or miste, comming with great swiftnes towards them: and with such a smoke, as if Mountaynes were all on fire: and to the view of some, it seemed as if Myliyons of thousandes of Arrowes had bin shot forth at one time, which came in such swiftnes, as it was verily thought, that the fowles of the ayre could scarcely fly so fast, such was the threatning furyes thereof.
The similarity to the Japan tsunami is striking. In a more recent paper, Haslett and Wong argue that boulders left by the flood could have been moved by a 4-meter tsunami.
To get a tsunami, an earthquake needs to have happened. The problem here is that a strong tsunami requires an earthquake of magnitude 7 or higher. This is because of the vast amount of water that needs to be displaced: the originating earthquake needs to lift or drop a correspondingly large volume of the subsea rocks. But there is no record of such a strong earthquake. The Bristol channel does have earthquakes, and in fact Walter Yonge reports that there was a small earthquake felt in Barnstaple on 12 May 1607. But these earthquakes reach at most magnitude 4. Proposing a much more distant earthquake does not help: this would have produced tsunamis in many different regions, not just the Bristol channel. The magnitude 8.2 Lisbon earthquake caused a tsunami in Cornwall (although not very high as it coincided with low tide) but left the Bristol channel untouched. (The extensive continental shelf of the UK disperses the energy of any tsunami far from the coast and this protects the coast fairly well.)
A large, local tsunami can also be caused by a major landslide. In fact the highest tsunami ever recorded was caused by a landslide, triggered by an earthquake: the 1958 Lituya Bay tsunami, with a run-up height of over 500 meter! The video is about this event. An older example, not as large but more destructive, happened in the year 536 in Lake Geneva. But again, there is no evidence for such a landslide within or near the Bristol channel.
As an aside, tsunamis can also be generated by volcanic eruptions, in a variety of ways. The volcano may suffer a flank collapse, sending a huge slide into the sea. There may be a large explosion in shallow water. And finally, a descending pyroclastic flow can push up the water They are the largest cause of volcanic fatalities. Krakatoa is a good example. The top two of the VC list of dangerous volcanoes both threaten volcanic tsunamis.
For the 1607 event, the same tract that seems to describe a tsunami later reads:
“But so violent and swift were the outragious waves, that pursued one an other, with such vehemencie, and the Waters multiplying so much in so short a time, that in lesse then five houres space, most part of those countreys (and especially the places which lay lowe,) were all overflowen.”
Five hours is far too long for a tsunami. The Lisbon tsunami came within 15 minutes and that is typical. The lack of a clear cause, and the slow onset, argue that for the 1607 event, no tsunami was to blame.
Spring tide
The long duration of the flood made it rather likely that a high tide would occur during the flood, making the impact much worse. But not all high tides are the same. Twice every lunar month the Sun and the Moon pull the sea water in the same direction, and a spring tide results, higher than usual by about a third. By bad luck, this was the case on the day of the flood. (The opposite effects gives rise to the neap tide, which is a wimpish high tide.)
The calculated height of the tides in the Bristol Channel, for January 1607. The peak on 30 January was extremely high. Source: Kevin Horsburgh and Matt Horritt, 2006.
But not all spring tides are the same. The Earth is closer to the Sun during winter, and this makes the spring tides notably higher at this time. However, at that time the Sun is very low in the sky from the northern hemisphere and this mitigates its effect and makes the highest tides come a bit later, February-April. Furthermore, sometimes the Moon is better aligned with the Sun. Finally, the distance to the Moon varies a bit. NASA calls the closest full moons a ‘Supermoon’ – a bit hyperbolic for something they advertise several times per year (and a closest new moon is just as interesting and has the same effect, but isn’t visible expect when it causes a long total solar eclipse.) The net effect was that the tide at 9 am on Jan 30, 1607, was the highest for 4.5 years. It magnified the impact of the surge, as it came on top of an already extreme tide.
(The origin of the word ‘spring tide’ is far from clear. After all, it happens twice a month! The word ‘neap tide’ is better understood: it comes from old english, when ‘nep’ meant ‘low’. The word ‘spring tide’ may also have ancient origins. The highest tides in Europe happen around the start of spring, and this a natural explanation for the name. The comments below have more discussion on this.)
On the morning of the flood, the tide at Avonsmouth would have peaked at 7.86 meter above mean level (AOD). This was very high. The full range (high tide to low tide) was 14 meters. However, in itself this height would not have been a cause of concern: this level was reached on occasion, and the differences with more common high tides were only some tens of centimeters. For comparison, the highest such tide in the 20th century was 8.04m in 1922.
But these are just the calculated values. The actual height can be affected by other things. Weather, mainly.
Storm surge
The water on that was not just the extreme high tide. The morning tide was 2.5 meters higher than that in the evening. The obvious cause was a westerly gale driving the water up the funnel of the Bristol channel. Many of the contemporary reports mention the wind:
“But the yeere 1606, the fourth of King James, the ryver of Severn rose upon a sodeyn Tuesday mornyng the 20 of January beyng the full pryme day and hyghest tyde after the change of the moone by reason of a myghty strong western wynde.” (John Paul, Vicar of Almondsbury)
This storme begane at 3 of clock in the morning and continue tyll 12 of clock on the same day” (Barnstaple Parish Register, 1607)
the wind blowing hard at south-west (Bristol town clerk)
The westerly wind aimed directly at the Bristol channel, raising the water levels by 2 meters or more. Modeling has shown that an additional height of 2.3 meters above the tide could fit the pattern of flooding along the Bristol Channel. For comparison, the storm flood of 31 January 1953 raised the water along the North Sea coast by 3 to 3.5 meters, but the North Sea is far more susceptible to storm surges. It was not only the force of the wind: the long duration also played an important role.
This suggests that the cause of the disaster was a combination of a storm surge and an already high spring tide, helped by the limited maintenance of the embankments.
There is other evidence that the 1607 flood was a storm surge, rather than a tsunami. Flooding was reported for the following night on the opposite side of the UK, at King’s Lynn and Wisbech, on the Wash (a North Sea bay) in Norfolk. And on the far side of the North Sea, a severe northwesterly storm occurred in the northern Netherlands on 30 January, sinking five large ships (170 sailors died) and badly damaging ten more near Texel. The storm also caused flooding in Friesland, where the sea defences broke. None of the reports from the UK describe wind damage, suggesting the winds were not as strong there as in the Netherlands. Interesting is that neither do the reports mention heavy rain: it was stormy, but perhaps not particularly wet.
Storm surges are caused not only the wind. Low air pressure contributes too, as the lesser pressure allows the water to rise, by about 10 centimeter for every 10 millibars. A deep low-pressure system in the UK may have a central pressure of 960 mbar (even lower is possible), and this can contribute 50 centimeter to the surge.
The weather report
So what actually happened? The winter of 1606/1607 was a mild one with little snow or frost, and winds mainly between south and west. It was called a ‘flower winter’ elsewhere in Europe. The weeks before the Bristol flood had shown changeable weather with westerly to southwesterly winds. In the days after the flood, the winds became southerly and the weather good and mild.
The long duration of the storm suggests a relatively slow-moving low pressure system, which over the course of the day moved from the southwest of the UK to north of the Netherlands. It would have passed the Wash and King’s Lynn on the south, as flooding in the Wash can occur with a north-easterly wind. There was no flooding reported from the Thames estuary and London, south of the Wash, so we can assume that the centre of the system passed north of London. By the end of the day, the low pressure had passed north of the Netherlands, as shown by the northwesterly storm there. The low pressure may have crossed Denmark at that time.
I now quote a comment provided by Neil Law on the earlier version of this post. Neil is a keen surfer with experience of surfing the Severn Bore. He wrote:
I sought out an expert, the world’s leading tidal bore surfer, Steve King. Not only has he been riding the tides for something like 40 years, but his family have been working the river (mostly running local ferries) for at least 400 years. He lives right on the banks of the river in the village of Saul. Now we had had a much bigger storm approach the UK from the SSW only a year or two before that which had no effect on the wave. I asked him why. He said that to have any significant effect on the wave in the estuary, any storm needed to be positioned 100 miles South of Cork, and needed to be 970 pressure or below. Hence the swell window for the estuary is very small.
Now that is not academic data, but subsequent experience has shown that it seems to be true. If I take it as actually being true, then whatever the source of the surge, the direction is pretty specific, and assuming it WAS a storm surge…and I think it probably was, then the centre of the storm was probably around that position, 100 miles South of Cork.
This suggests a storm track as shown below. This should not be taken too seriously! I am very happy to accept the starting position, 100 miles south of Cork. The track shown crosses between the Wash and the Thames estuary before moving north of the Netherlands. The midday position is based on the report than the storm ended by that time. It also fits one report which states that the wind turned easterly in the Bristol channel after the storm. However, by and large the trajectory across the UK is a guess.
I will end this section with another comment by Neil Law, on the potential impact of the bore up-stream on the rover Severn:
One final point I would like to raise, whilst I don’t have any particular reports from specific locations… The extent of the Severn Bore. In 1607 there was no obstruction to the flow of the bore. These days it is normally brought to an abrupt end just North of Gloucester by Maisemore weir. The weir exists for exactly that purpose. For a relatively brief period both Gloucester and even Worcester were regarded as international ports. This was made possible only by the construction of the Sharpness Canal, which effectively bypasses the most powerful part of the Severn bore, and allows shipping access into and out of the river. To this day, it remains dangerous, and the harbourmaster at Sharpness is very strict about letting people into and out of the lock from the harbour into the estuary.
The canal was not built until 200 years after this event, though. When the tides are large ( 10 meters or over AND the river is high due to rainfall, we know that the wave will continue over the weir for several miles, although as the weir makes the river deeper than would otherwise be the case, the wave is too gentle to be surfable beyond Maisemore….and the activity is specifically banned by the Port of Gloucester above the weir anyway. As to how far the surge may have travelled? A friend of mine was once the lock keeper at Tewkesbury, and he tells me that on any large tide (which will always overtop Maisemore weir…eventually) even if no surge is visible, the huge lock gates just South of Tewkesbury would always deliver a loud “Boom” when the tide arrived. So I think significant flooding as far upstream as Tewkesbury is certainly a possibility.
The Great British tsunamis
Although the UK is fairly well shielded from tsunamis, there have been exceptions. The worst tsunami to hit the UK during its habitation hit Scotland, around 8000 years ago. A big landslide of Norway caused a wall of water 20 meters high which overran much of the Scottish coast, leaving a layer of sand up to half a meter thick. Some of the Shetland islands may have been inundated completely. Further south, the coast was not yet in its current location. In the middle of the North Sea was a marshy, inhabited region known as Dogger bank. Nowadays it is 20 meter below the sea. The bank must have been wiped clean by the tsunami.
The only other confirmed UK tsunami was in 1755, followed the M8.4 Lisbon earthquake. The tidal wave was 2-3 meters high in Cornwall, but little damage was done as the wave came in at low tide; the wave also did not travel further up along the coast.
Several other tsunami-like events have been reported. An example was in Brighton on the south coast, 20 July 1929. A large wave, 5 meter high, suddenly swept up the busy beach. The wave was caused by a large thunderstorm just off the coast: the wave is caused by a sudden pressure change of several millibars. These are called meteotsunamis and in the UK tend to occur in summer, mainly June or July. There can be a volcanic connection: the atmospheric pressure wave of the Hunga Tonga eruption which measured 2mbar in Manchester (and over the next few days passed 7 times over the city), produced meteotsunamis in several places around the Pacific, before the main oceanic tsunami arrived.
There is no known connection between the 1607 Bristol flood qnd meteotsunamis. A storm surge coinciding with a very high tide is improbable, but wait long enough and the improbable is likely to occur. And so it did.
A warning
What happened before can happen again. Risk analyses must take this into account, and preferably plan for events worse than anything that has already happened. The Bristol channel area is much busier than it was before: more than a million people live near it. The flood defences have improved, and a similar event as in 1607 may be manageable. But could worse happen?
Predicted flood levels for an extreme, 1607-like event. Source: RMS Special Report, 2007
Adding an extreme tide an an extreme storm surge gives a possible sea height of 9 meter above AOD at the tip of the Bristol channel. Modeling has been done for such a situation, which in places would overwhelm the existing defences. Extensive flooding around Cardiff and Swansea would occur, and the material loss could exceed 10 billion pound. The question is how realistic such a situation is. There has been flooding around the Bristol channel a number of times in the past century; in the wet winter of 2014 it was due to the incessant rain, but at other times it was caused by storm surges, the highest of which reached 1.5 meter. The surge level is therefore not out of the question. The danger is when this coincides with a spring tide. Such a coincidence of course is rare. Is the combined risk acceptable? As sea levels rise, the risks increase, and what is rare now may become common within a century.
Power stations at Hinkley Point. It is not known why they carry a three-eyed emoji.
But now there is more at stake. Somerset is the location of Hinkley point, where a new nuclear power station (Hinkley Point C) is to be build. Power stations need access to water for cooling, and so they are build close to water, but obviously above the flood line. The Hinkley site has a low (but non-zero) flood risk. However, with 0.5 to 1 meter of sea level rise, the flooding risk will become significant. After the Fukushima disaster, nuclear projects have become very aware of the risk of over-sized waves. To avoid anything similar, the sea wall at Hinkley is 13 meters tall and the platform itself 14 meters.
Final comments
After 400 years, the 1607 event remains famous. The idea that it was due to a tsunami does not stand up to scrutiny: it was a storm surge, badly timed to coincide with the highest tide for four years. Even so, the flood marks in the churches are not as high as might have been expected. Is this due to the sea being lower or the land higher 400 years ago? Or are the markers not always correct? There are aspects we do not understand well. It is clear that this could happen again. How good are the defences? In the UK, sea defences are judged on economic benefit. In the Netherlands, they are treated as defensive weapons where any defeat is disastrous. Different attitudes give different outcomes.
In the end, it is all about the weather. Whether the sea can conquer the land is up in the air.
Source: Golcar Matt, BBC
Albert, November 2024
Sources
The Bristol Channel floods of 1607 – reconstruction and analysis. Kevin Horsburgh and Matt Horritt, 2006, Weather, 61, 272
1607 Bristol Channel Floods: 400-Year Retrospective RMS SPECIAL REPORT, 2007.
http://forms2.rms.com/rs/729-DJX-565/images/fl_1607_bristol_channel_floods.pdf
The Severn Tsunami? The Story of Britain’s Greatest Natural Disaster. 2007, Mike Hall
Historic tsunami in Britain since AD 1000: a review. S. Haslett, and E. Bryant, 2008, Natural Hazards and Earth System Sciences, 8, 587–601
Recalculation of minimum wave heights from coastal boulder deposits in the Bristol Channel and Severn Estuary, UK: implications for understanding the high-magnitude flood event of AD 1607. S. Haslett, and Bernardine R. Wong, Atlantic Geology, volume 57, 2021, p. 193–206. https://doi.org/10.4138/atlgeol.2021.009
Weird weather in Bristol during the Grindelwald Fluctuation (1560–1630)
Evan T. Jones, Rose Hewlett, Anson W. Mackay Weather, Volume 76, 2021, Pages 102-120, https://doi.org/10.1002/wea.3846
Meteotsunamis at global scale: problems of event identification, parameterization and cataloguing. V.K. Gusiakov, Nat Hazards 106, 1105–1123 (2021). https://doi.org/10.1007/s11069-020-04230-2
Thanks Albert. Strangely there is a TV programme on channel 5 tomorrow.
According to insurance and EA flood reports, the risk of flooding in Bridgwater is listed as highest from sea flooding, rather than river flooding. The River Parrett is tidal as far inland as Langport, in the heart of the Levels, a distance of around 30 miles I think. The whole area is full of waterways, both natural and man made. There are large flood relief channels and the farmland is often allowed to flood to protect Bridgwater and Taunton.
The flooding of 2014 was due to a number of factors. It had been wet fir large parts of the previous summer, continuing into autumn and winter. There were a number of successive storms (which would now be named storms), causing flooding in various parts of the UK. In January 2014, a storm came in across southern Britain and may well have had a similar track to your suggestion for 1607. The flooding in Bristol in January 2014 was largely due to the storm surge occurring at the same time as a spring tide. In Bridgwater, the high tide caused streams flowing into the Parrett to back up, as the high tide prevented outflow. This led to flooding adjacent to the river. I’ll try to post a video of this below. The high tide was higher because of the spring tide, the storm surge and the particularly high river levels. I wonder, if with only a slight adjustment to the track of the storm, whether the flooding could have been much worse. The flooding in Bridgwater did occur more than once over that period, so the biggest effect was probably from high river levels, so it was probably a near miss.
https://youtu.be/jaL0ms-IzDU?si=su1d2ckOO7IHmF8g
There is a PDF report on the Met Office site. The chart for 4-5th February shows how close the storm was to a direct hit on the Bristol Channel.
Some of the earlier storms had pressures as low as 940.
https://www.metoffice.gov.uk/weather/learn-about/past-uk-weather-events#y2014
And some images.
https://ps.avalonlightphotoart.co.uk/gallery/Bridgwater-Flooding/G0000R1lz_s3QLcw/C0000CLspIPFY8EE
Certainly sounds like a storm surge. The low pressure system that hit Washington state a few days ago was running at 940 mB, which would cause several metres of storm surge despite technically not being a hurricane.
A tsunami would’ve been seen all along the European coast, but if the low pressure system was aligned just right it would devastate Bristol and almost nowhere else – since Bristol is at the end of a narrow triangular estuary.
The one we’re all worried about of course is La Palma. If half the island slides into the sea the result will be a devastation that none of us has ever imagined.
Yes, if the Lisbon Tsunami wasn’t really severe in Bristol Channel, it is impossible to imagine a stronger tsunami by smaller events. I’d expect that the Atlantic ocean has fewer tsunami risk than the Indian and Pacific Oceans.
La Palma or other Canary islands are a possible dangerous threat, but very rare in natural history.
Like all possible natural disasters of a transient nature, the question is does it pay to put in adequate defences and maintain these for centuries, as against doing repairs once a century to your property (which may well be covered by insurance if it’s that rare)?
1) Man with house on Somerset levels, where flooding is common: built an embankment round his house and now survives floods unaffected.
2) The Thames barrier, which protects tens of billions of pounds worth of property and is used increasingly often (to precent flooding as well as high tides).
3) Put house on stilts (Florida) or flood proof (uk) so flooding is prevented/resisted by your house.
4) Move somewhere safer.
5) Hope someone else will else your problem.
Cost is a real issue. But it is not only about property. Both the 1607 and 1951 floods had over 2000 fatalities (in 1953, most of those were not in the UK). The US seems to forego flood defences in favour of large scale evacuations and shelters, which is another way to protect lives. The UK doesn’t do evacuations.
Available space and suitable shelter will partially dictate evacuations. In February 2014, the villages of Moorland and Muchelney were both subject to emergency evacuations. That was more after the event though.
The person who built barriers around his house was very unpopular locally. He was a prominent wealthy businessman and he was criticised for his lack of community spirit. It was also suggested he made the flooding worse for other properties nearby, as it was near to Moorland.
Yeah, right!!. Foaming at the mouth jealous more likely. After all many could have done the same and the idea that it increased the flooding for others is laughable. It was his house, not the entire farm (which I think he did not own).
In a similar vein was the Australian who cut a firebreak round his house by daring to fell (his own) trees and got fines $100,000 Au. Within 12 months a wildfire had incinerated the local town and all adjacent properties and the guy said it was the best $Au100k he ever spent.
I have electricity backup.Every time there is an extended power cut (ave 1x annually) my neighbours whine at me and complain about the (well silences) generator. but never buy their own “because it won’t happen again”. Now I have solar with batteries and since my system carries on powering the house without me being aware everyone else has no power, they now whinge at my house having heat/ligh/tv/internet and complain its unfair that my batteries power my house but their solar/batteries switch of when the mans goes off…
It’s the way of the world :P.
I don’t know which of the largish family it was, but one of them worked hard to make their fortune. The sons have started their own businesses and as far as I’m aware they are just as successful.
BTW, I started the trend in my road with solar, I haven’t had any complaints, but then I probably don’t go anywhere to hear them anyway.
Like Farmeroz, my first response was ‘envy’ – good luck to the guy with the floor barrier. I would have preferred not to live on the floodplain, though. With more rain and higher sea level, the problems will get worse, not better. Nature’s answer is ‘sediment’: a series of good floods can themselves raise the land. That is how a delta works. But it doesn’t work if you also want to live there.
The most amazing thing for me was the number of people in high sided vehicles who thought they could drive through the flood water. The lucky ones were able to reverse back up the road… The flood waters were almost to the height of single story buildings on the main road from Taunton to Glastonbury. They have since installed flood gates on the roads most prone to flooding, similar to snow gates in Scotland.
There was also a lot of discussion around dredging of the rivers. The Environment Agency got a lot of criticism for not dredging, but it was a previous discussion amongst a number of groups that lead to the decision. There was also real concern that dredging would increase the risk to Bridgwater and other larger villages and towns downstream from tge main floodplain. When the rivers were dredged, the EA were on high alert overnight and erected barriers to prevent flooding in Bridgwater.
It was eco-reason to improve the biodiversity and promote flooding of the old water meadows to allow ‘nature’ to return. The environment agency was happy to oblige despite the local farmers (what do they know, the would say that etc etc) pointing out that more flooding also had wider problems. Anyway, wait until there are 10,000 beavers with their (wildlife protected) dams and then discover the consequences.
Bridgewater town council probably allowed (even encouraged) inappropriate placing of new development.
It wasn’t relating to biodiversity and it may have been farmers who didn’t want them dredged, there are different stories. Largely though it was to protect the larger population centres. Lowland flood plains aren’t really particularly suitable for beavers and there is quite a bit of evidence that introduction of beavers in upland woodland wetlands actually reduces flooding. Felling of upland woodlands and the digging of flood channels has contributed. Flooding of upland woodland and returning rivers to their natural winding routes is reducing flooding in many areas, as it slows water flow.
Inappropriate developments could apply to the whole Sedgemoor area over hundreds of years. The whole of Bridgwater is on a floodpkain, as are many areas of other large towns adjacent to the Somerset Moors and Levels.
The farmers DEFINITELY DID want them cleaned regularly. The decision by EA to stop cleaning ditches was all over the agricultural press for a year or more as it very adversely affected the farmers (and huge tracts of the UK if extended). It was done because we need more wild wetlands according to govt edict. It’s a similar argument for not maintaining sea defences because its natural for coastlines to be eroded (true) and reduction may have reduced gravel banks and perhaps sandy beaches further down the coast. I’m not sure if it actually made any difference in the end.
The essence of managing very heavy rainfall is extremely simple. Either speed it past key areas or pond it so as it doesn’t uncontrollably reach key areas. The problem with the UK is that all lowlands are settled, some more than others, so not everyone can be protected.
The bigger problem isn’t so much that the lowland floodplains have been settled, but more that those settled areas are often the larger settled areas. Most of the larger towns and cities are in lowland areas. That complicates the options, as speeding up flow and allowing it to pool downstream puts those larger centres at greater risk. We can argue that they shouldn’t have been built there, but reality is, they are already there and in many cases, have been fir centuries or even a couple millenia.
The only option then is to allow water to pool further upstream and that has been the purpose of the Levels for a very long time. The Levels (and Moors) are deliberately flooded most winters to protect the larger population centres downstream.
Flooding is equally bad for wildlife (with some exceptions), so it doesn’t make sense to deliberately flood for that reason. The wetlands have always been there, until humans decided to drain the Levels. The land management probably goes back to the Neolithic era and the constant drainage has further reduced the land level. When rivers run above the height of the surrounding land, there is always the potential for disaster.
In many areas now, there are “wiggling” projects to return the rivers to a more natural flow, this slows them down in a similar way to the flooding of upland wetlands. It also serves a similar purpose to the flooding of the Levels.
The more humans try to fight nature, the greater the chance for disaster in my view. Instead of fighting nature, try to work with it and there will probably a better outcome. It’ a bit like trying to stop lava flows, rather than diverting them.
Widespread upland deforestation has also increased the flow into the river systems. The combination of deforestation with building on some of the more flood-prone areas has accelerated the problems.
We can apply here the theory of evolution: Can we – as humans – adopt to the challenges and conditions of nature? Usually not the strongest animals survive, but the ones which adopt best to external dangers or find ways to cooperate fortunately.
There are risks that are unpredictable and inevitable. That are rare volcanic eruptions, exceptional earthquakes or rare meteorological disasters. We can’t prepare – because we don’t know – and we can’t learn for next time, because until next disaster we and our kids are long dead.
One potential risk for future Atlantic Ocean tsunamis is the cause of climate change in Greenland. There can happen “Storegga tsunamis” if frozen shelf or mountains collapse, if permafrost retreats further.
Kilauea might be heading southwest again, surprisingly. There isnt as much uplift at the last eruption site, while SDH is shooting up again like it was earlier in the year.
Kilauea Iki and ESC also have inflation. It looks as if the whole summit and upper ERZ get magma inflow. But it can be a short term development. How can we interpret the gas monitoring near SDH?
Its very small, gas monitoring is useless at Kilauea unless it has an open vent, I remember it being a big deal before 2020 that SO2 was so low but it erupted with no warning spike in emissions. Some volcanoes are highly fumarolic but Kilauea isnt one of them at least not focused to one point.
I do find it pretty fascinating how the volcano with the highest magma supply, and most SO2 rich magma, is somehow able to drop to near nothing when a vent isnt open. I would suggest it has no hydrothermal system except we have seen directly that isnt true back in 2020 when the worlds hottest lake formed in Halemaumau. So I guess the rock must just be really impermeable at some depth between the magma and groundwater.
http://www.mounts-project.com/static/data_mounts/kilauea10/2024/kilauea10_20241111T161642_20241123T161641_VV_ifg.png
Interferogram from a few days ago showing indeed the area south of the caldera is uplifting. This doesnt show the recent much stronger tilt signal just above either, which started only after the interferogram timeframe ended.
Pu’u O’o tiltmeter is still tilting to the east and south so there does seem to be uplift in the middle ERZ still, but the GPS isnt going up as fast there now as before. GPS at and east of Pu’u O’o show slight uplift so tilting there isnt caused by subsidence anywhere nearby.
The sputh caldwra area did subside a lot in the last eruption, the ERZ seems to start here, so maybe not surprising to see rapid uplift. This might be a sign of eruption being likely soon, the ERZ filled up so now only the summit needs pressure. A new intrusion might be likely before mid December. If it is from Napau/Makaopuhi then an eruption is very probable.
A fascinating article! Thank you!
The Bristol Bay and Channel have a funnel shape. This forces inflowing water to rise. Maybe there was a historical special effect with storm surge, spring tide and the “perfect moment”. Concerning storm cyclones, time also matters. How long did it have time to push water in the bay? Did it carry a mountain of water over the Atlantic ocean?
Maybe a big storm surge of water travelling over the Atlantic ocean acted like a “meteorological tsunami”.
If Canada is very cold (Little Ice Age), New Foundland produces cyclones/depressions like a factory. That’s why cold winters in eastern Canada often make Europe hot; and mild winters in eastern Canada let Europe freeze (with lazy antidepressions).
The deep lows tend to undergo rapid cyclogenesis in the Eastern Atlantic, but it also depends on the path of jetstream.
Yes, there are many ways and variations of development for a “winter hurricane” (storm with hurricane force winds). It is difficult to imagine, where the Bristol cyclone began, where it deepened and where it walked.
We know that hurricanes and winter storms can do big waves at large distance. F.e. the Jaws on Hawaii: https://en.wikipedia.org/wiki/Peahi,_Hawaii#Pe'ahi_(Jaws)
The reports in Albert’s article don’t mention the wind first, but the flood. Maybe the Waves entered the Bristol channel, before the storm followed. The Atlantic ocean allows a mass of water to move in the foreground of a storm. That’s different from storms in the North Sea, Baltic Sea or Med. Sea.
Another type of big waves is the Rogue wave which is created by accumulation of many waves in a giant one: https://en.wikipedia.org/wiki/Rogue_wave
Quite glad I live next to the Tyne, 200m up. I only have to worry about the next Storegga slide.
Down to one vent (northern with flow to east) at Svartsengi. IMO says activity hasn’t slowed down as quick as last time, though it doesn’t seem like this episode will last as long.
I was a bit surprised at first by the comment from IMO, since we are on day 5 of the current eruption and as you say are now down to a single vent with relatively low fountaining, while the previous eruption was still going strong with at least two much taller fountains after the same amount of time, IIRC. On the other hand, the current eruption did not start out as voluminous as the last one, so perhaps it is a slower decline in a relative sense.
I agree that it looks like the eruption won’t last much longer, unless we get to some sort of quasi-steady state like the one earlier this year that lasted a couple months.
I’m enjoying the updates from IMO. My browser gives me an opportunity to convert the text to English, which is a lot of fun. Here’s today’s update:
Dinner party? Uterus? Land continuing to gypsy? Obviously the AI is having a bit of trouble with Icelandic. 😀
I expect it meant “land continues to subside”.
I think these eruptions have a Holuhraun-like aspect, in that the magma is being forced out by something that has stored potential energy. In the Holuhraun case, this was gravitational energy stored in the “piston” above the magma chamber. It dropped, very noisily, and squeezed the lava out like stepping on a ketchup packet.
The sill under Thorbjorn is a bit different. Though the uplift when it inflates must be storing a small amount of gravitational energy in the roof, which then contributes to the eruption’s force when the next fissure opens, I think the majority of the energy is being stored as tension. The sill is now nearly aseismic; the quakes that are happening are mainly along the fissure lines, caused by dike propagation. That the sill is able to inflate and deflate quietly points to the wall being fairly ductile. It’s not cracking, nor are mobile blocks of the roof pistoning, or we’d get the same kind of noisiness that Bardarbunga’s caldera made during Holuhraun. Instead it is stretching and contracting: a magma bladder. The bulk of the energy powering the eruptions is in the wall tension, with assists from the roof’s gravitational energy and from gas pressure. With gas pressure alone we’d get eruptions more like Fagradalsfjall: longer and more steady in rate, rather than starting out with a much higher rate and decaying exponentially. The two eruptions that persisted for several weeks at one vent ran out of sill-tension (and roof) energy as fast as the others, but managed to survive on gas pressure for a while before the conduit clotted up.
The same thing happens if you inflate a balloon and then let it go without tying it off. It will rocket around the room, farting the whole while, before eventually settling to the ground somewhere, empty. While you’re holding it after inflating it but before releasing it, the pressure inside is elevated, but the vast majority of the energy it stores is in wall tension, not the pressure difference with the outside air. When you let it go, the wall contracts and pushes the gas out: energy moves from wall tension into the pressure difference, and then into kinetic energy in escaping gas. (And it is, in fact, technically a rocket: it has an internal store of propellant, which it ejects from its rear, causing it to move forward per Newton’s Third Law. It’s not instead pushing against something external to move itself, as a jet or most any other type of propulsion system would do. Making the material stiffer, with a higher spring constant, would make it go farther: though it would have the same volume of propellant when fully inflated, the higher amount of energy stored in the wall would give it a higher exhaust velocity and thus more delta-V. It would take correspondingly more effort to inflate it: conservation of energy.) The Thorbjorn sill differs in that it’s a) rooted to the spot and b) squirts lava rather than air.
I’d assume that the present location of the eruption is the “central vent” of the volcano. The eruption in August in the North was like a fissure swarm eruption; there was also one early this year in the south close to Grindavik. But the majority of eruptions is probably going to happen in the central volcano.
The present eruption is like the central volcano eruptions of Grimsvötn, Bardarbunga, Hekla or Askja, while the northern eruption in August was more like the fissure eruptions in Holohraun or Laki. Also Hekla did infrequently effusive eruptions on the fissure swarm, 50 times during Holocene, but the majority of eruptions happens at the central volcano.
Officially the volcanic systems on Reykjanes Peninsula have no central volcano. But the lack of eruption monitoring experience probably causes a underestimation of the central vent of the systems. If we look at the big volcanoes like Bardarbunga and Askja, their volcanic systems nearly cross the whole Iceland/island, just as the smaller system nearly cross the whole Reykjanes Peninsula. Micro volcanism may mirror macro volcanism on Iceland.
I don’t agree with the notion of a central vent. A central vent normally refers to the top crater of a volcanic edifice. No such thing exists here. These are fissure eruptions in a rift zone. The sill serves as a temporary magma storage in the shallow crust, but the eruption mechanism, fissure orientation, etc, are dictated by the spreading direction of the tectonic plates, and not controlled by a central volcano.
The shape of the sill (or sills) is elongated in an E-W direction that follows the plate boundary. This direction is oblique to the spreading direction. The dyke and its eruptive fissures have a SW-NE orientation that’s aligned with the spreading direction. The place where the swarm initiates at the start of an eruption is the same spot that keeps steaming the most between the eruptions. This is also the spot (within a few 100 meters) where the fissure crosses the plate boundary (as inferred by seismicity). It seems like a natural place for lateral magma transport from the sill into the fissure. Note that the main vent of the 2021 Fagradalsfjall eruption is also located near the inferred plate boundary.
It was a bit tempting for me to compare the small volcanoes with the big ones …
The present location still is the probably main location for most eruptions. Between Sylingarfell and Fagradalsfjall’s Fjell is the broad lava field of Dalahraun. It shows that both historical and pre-historical eruptions have accumulated most lavas in this area.
If Geldingadalir 2021 wasn’t surrounded by the Fjell (the shape reminds to typical Scandinavian fjells), the lava flows would have had the possibility to run west and meet the current east running Sundhnukur lava flows.
Looking at GPS, inflation seems to have resumed. Too early to say whether it is sustained.
An excellent analysis of the Bristol ‘Tsunami’ !!
Couple of thoughts:
UK ‘hinge line’ between Scottish post-glacial isostatic rebound and Southern second-order sag runs Mersey to Hull. Western edge creaks and groans along many minor faults. Historically, these interrupted coal seams, beset deep-mining. Recently thwarted gas fracking. While London’s slow descent makes the news, can we estimate how much ‘sag’ has occurred in Bristol area since ~1600 ??
Mersey regional authorities face enough flood-plain problems that a ‘Barrage’ is again being considered. One low-ish Mersey barrier at South end of Liverpool seems cheaper, safer and much less unsightly than building and maintaining umpteen miles of flood-walls further up-stream. And pay for itself with tidal power…
I’m so glad I live on a sandstone ridge with reassuring Medieval dry-foot suffix, ‘On the Hill’. But, dire ice-cap collapse could inundate much low-lying former marsh to our North West –Martin Mere etc !!– and give this ridge a sea view…
.
Sometime in the next 10 years, I am sure this record will be broken and everyone will be talking about how unforeseen the disaster was when in reality the writing was on the wall. Great article
They already have made the experience of “Bert”: https://www.bbc.com/news/articles/c93qe00lw34o
Time’s a ticking!
Why has the time shown in the comments been changed to a 12 hr clock, showing PM but not AM? This doesn’t agree with any standard that I’m aware of, nor does it agree with the times shown on Hawaiian or Icelandic webcams. It just makes it more difficult to quickly compare times.
The timestamps show up for me as 24 hour clock times, and I presume (from the times referenced) that the time is UTC – which is 100% correct, it’s the worldwide standard time reference, it’s the one we use in all our observations.
The 12 hr clock time only lasted for a while in the last 24 hrs; it’s back to the 24 hr clock now. It must have been a temporary glitch.
B Bound, is that you?
once again thank you Albert for another great article.
Deep dive into Askja, Some beautiful pictures as well
https://www.reuters.com/investigates/special-report/climate-change-glacier-volcanoes/
OT: Another great picture from NASA, this time showing the recent Sundhnúkur eruption and the lava flow encircling the Blue Lagoon:
Those satellites come in handy!
The full article can be found here:
https://earthobservatory.nasa.gov/images/153630/lava-nears-icelands-blue-lagoon
I hadn’t realized that the sea is so close also on the northern side of vents!
What’s the chance that the lava will at some point start threatening Vogar and even Njarðvík?
Especially if its conduits to other directions are artificially blocked?
That was from the previous eruption, in which the dike unzipped further north and we had a couple long-lived vents on the northern side. But, the land is pretty flat there, and the lava front was advancing very slowly to the north. I would imagine the roads and towns up there are mostly safe for now unless the dike zips open even more to the north in subsequent eruptions and/or subsequent eruptions last much longer.
New map just dropped…
https://www.vedur.is/um-vi/frettir/eldgos-hafid-a-sundhnuksgigarodinni
“It is expected to continue flowing subsurface towards the protection walls near the Blue Lagoon. The Northern crater is the only active one with lava flows to the East.” (Specialist remark)
But in the news they say that the “majority of lava from this vent is flowing eastward toward Fagradalsfjall”
The eastern lava flow has reached the base of Fagradalsfjall’s Fjell (which hosts Geldingadalir) as the lava map shows.
New MBL article with expert Kristin Jonsdottir: https://www.mbl.is/frettir/innlent/2024/11/27/hraunflaedid_i_att_ad_svartsengi_lokid_i_bili/
She says:
– No sign for an ending eruption
– Lava runs clearly east; flow towards the west has probably ended (contrary to the opinion of the Specialist Remark)
– the eruption can continue with a few cubic meters per second for some time
The specialist remark also says that the northern vent, with a flow to the east, is the only active one. It does say that the lava can continue to flow under the crust, which is what we saw in June, when the eruption had clearly ended, but some lava still managed to flow over the protective berm. The lava remains fluid under the cooled crust and gravity will continue to redistribute the already erupted lava for a while, even after its feed has been cut off.
The mbl.is Sandhóll close up cam shows a nice view into the remaining vent, where lava is splashing around in a way that brings back memories of the Litli-Hrútur episode.
Yes, it reminds me much to some of the Fagradalsfjall (e)vents, and the eruption rate is aligning to the Fagradalsfjall scale.
Fagradalsfjall did one eruption every year 2021-2023. The first was very voluminous, but the following two relative small. How close is the current Sundhnukur volume 2023-2024 to Fagradalsfjall I? Has the general magma inflow in the system increased?
The combined total for Sundhnjukur is way more than at Fagradalsfjall, I dont remember specifics but it was something like 0.25 km3, maybe 0.3 km3 now. If the 2021 eruption lasted a year it would be in this range too but it didnt.
Im not sure the supply has gone up necessarily, but Sundhnjukur does seem to have an easier path up at least to the upper crust. It was building up to this intermitently for nearly 4 years before it broke, and now another year that repeated eruption and rapid decompression refilling.
If Fagradalsfjall is connected I dont think it can erupt anymore, maybe when Sundhnjukur stops, but I personally am a bit sceptical now. An eruption like 2021 might well happen at Sundhnjukur though when the magma path is too open to build pressure. The August eruption might have been the peak in intensity and absolute scale but I doubt it will be the biggest single volume. Arnarseturshraun is like this, maybe the current eruption becomes like that, or one a bit later next year.
Today’s Icelandic update:
1. Lava continues to run east/southeast
2. The eruptions is constant
3. Significant sinking (=deflation) around Svartsengi
The eruption is different to Fagra I with the continuous behaviour. No pulsating or “Geysir” like changing activity. Maybe the eruption is more like the Fagra II and III eruptions. Retrospection on Fagra III: https://en.wikipedia.org/wiki/Fagradalsfjall#2023_eruptive_activity
The early 17th century also had some desastrous storm surges in North Frisia that led to the collapse of the big island “Strand” (beach in English). The final “doomsday flood” was the Burchardi 1634 during 30 years war.
The Frisian like the Dutch coasts are so flat that islands often only were 1-2 meters above sea level. By human land use (draining, turf harvest) and geological deflation (reaction to Scandinavias inflation) they lost this difference. Both the old coast line and old islands were lost.
Kilauea is showing a little activity with around 17 quakes around PUHI.
Mac
So this article makes me wonder… how was the weather in the Low Countries, Netherlands and Belgium? Roughly about the same, or different. I remember the big flood in the early 1950’s. But earlier then that? No clue.
The January 1607 storm hit the northern Netherlands with a lot of sunk ships. The storm track must have been somewhat like yesterday’s, from southern Britain to Denmark skirting the Dutch coast.
Except yesterday’s storm mostly missed SW England.
Yes, the track and storm was not identical. But it gives an indication of the kind of track
It shows how narrow the margin is. It’s probably less than 50 miles between tracking up the Bristol and English Channels. Also Conal also deepened after crossing the UK
It wasn’t probably the “perfect storm” for the Netherlands unlike the 1953 storm. Maybe there is a difference between severe Atlantic storms (Ireland/UK) and severe North Sea storms. The tracks and developments are a bit different and cause big differences on the local coasts.
The most famous North Sea storms during last centuries were: 1634, 1717, 1825 and 1962.
Hard to compare these. The main floods along the North Sea coast come from storms moving along the north of Scotland to Denmark or Norway. These keep northwesterly winds which causes high water surges. Storms coming from the Channel (Channel rats) can give worse wind but mainly from the southwest, with less surging. The 1953 storm I think was a northerly one. Ireland and the western UK are more affected by Atlantic storms. The strength of the storm depends on the track and on interaction with the jet stream, so storms don’t really repeat themselves. Every one is different.
There are quite a few articles on the 1953 storm, although most concentrate on the impact. I can’t find it again, but one article ( from Met Office I think) stated the minimum pressure was 966 mBar. It tracked across Iceland and the Faroe Islands, before turning south through the North Sea. There was rapid deepening through that phase, but it filled before it hit the Dutch coast. The storm surge was amplified and another article indicated surge heights ofv1.5-2 metres in Essex and Kent and 2.5 metres in The Netherlands. The North Sea narrows in a similar way to the Bristol Channel an the angle of the East Coastvif Engkand may well deflect surges towards the Netherlands and Belgium.
The Met Office also mentioned a storm in 2017 that followed a similar track. It had the highest surges since the 1953 storm, but defences erectedcas a resukt of the 1953 floods protected the coasts.
Here is the storm track from 1953, which was indeed a northern one, from https://www.frontiersin.org/journals/marine-science/articles/10.3389/fmars.2015.00084/full . It started near Iceland.
I found the Met Office article.
https://www.metoffice.gov.uk/weather/learn-about/weather/case-studies/floods
Some literature to start with, Richard:
https://en.wikipedia.org/wiki/Saint_Marcellus%27s_flood
https://en.wikipedia.org/wiki/Burchardi_flood
https://www.dhm.de/blog/2023/08/16/storm-surges-on-the-north-sea-coast/
In the last link you scroll down to find a map of the North Sea coast around 1240. It was more or less solid albeit with waterways in between. For today you go to maps. The solid land has disappeared back then and was fragmented in a row of islands, two in Denmark, three in North-Germany (Northfriesian Islands), then seven further south called Eastfriesian Islands, plus some sandbanks (Germany), then five further south and west belonging to the Netherlands plus sevearl sandbanks.
You will also see some Halligen which is s.th. different.
That change went on for about 300 to 400 years and might have come to an end with the onset of the Little Ice Age.
Pulsing behviour from he right-hand vent on https://www.youtube.com/live/IDIlqJfRaDg, reminiscent of what we saw at Fagradalsfjall, though less powerful and less evenly periodic.
Yes, I was noticing that, too. That vent on the right had been showing just the occasional splatter up until it started this pulsing behavior today. It’s pulsing up enough to send floods of lava cascading over the side of the cone. Definitely reminiscent of Fagradalsfjall but more random, as you say.
The Sylingarfell webcam inside the Mosaic view shows the active vent and lava flow well:
https://www.youtube.com/watch?v=kXD4A9uFHcg
The background shows Fagradalfjall’s fjell landscape and the slopes of the shield “Þráinsskjöldur”.
The webcam views show many steam spots on the lava field. Does the magma/lava have a high water content that is released here?
If we look at the daily VONA’s in the world, some ash plumes look high on first view, but often the volcanoes have very high peaks above 5km (f.e. Popocatepetl and Sangay). It is difficult to find out which volcano did the biggest eruption of the day. What is the biggest eruption in the world now?
I’m still here, although I can’t remember the last time I posted a comment.
I am now a “retired” bore rider. I’m still happy to surf at sea, but the Severn Bore, particularly on a bodyboard (my surf craft of choice) is a job for those who are younger and fitter than I am. It is most definitely an endurance sport !
Thanks for the name check, Albert .
The only thing I have to add is maybe a little insight , for what it’s worth, of the personal experience of being on that wave. The reason I think it might be relevant is the experience not so much of the size of the wave, but the energy of it.
Youtube now has hundreds, or possibly thousands of videos of the bore. Taken overall, I think they fairly reflect the normal range of what is to be expected, which would be something like a (usually broken) wave of between 2 and 4 feet in height travelling inland at speeds which are normally between about 4 mph ( at the seaward end of the run, around Arlingham/Newnham) accelerating to around 10-13 mph as it approaches Maisemore weir.
Subjectively, it feels much faster than that when actually riding the wave. This is mostly down to the visual cues you get when surfing a few hundred metres from either bank. Just inches in front of you, the river is still flowing normally, which means quite quickly.
Another factor which can convince a rider that they are travelling faster than they really are is the power of the wave. Now this is not the top-to-bottom power that I experience on a good reef wave, for example, where the wave can get “sucky” , creating barrels etc (hollow sections), although the bore does that too, when conditions are right. I refer to the push laterally… Inland. It looks like a broken wave, which on a beach would typically lose energy very quickly. The bore does NOT lose power like that. It is unrelenting, and far stronger than any sea wave of similar size.
In 2009 I made a mistake on a fairly weak tide producing a wave probably less than 2 ft high. I was unceremoniously rammed into a clay bank, resulting in 3 rounds of surgery on my wrists and an early end to my career as a musician.
Immediately after impact, with nowhere else for the pressure to release, I was propelled about 3-4 metres vertically. Popped out of the water like a cork from a bottle !
But anyway… That cost me about 18 months during which time I couldn’t surf.
Which brings me to storm surges.
The day I returned to the river in 2011 was stormy. There was a predicted tide of 9.9m ( measured from Sharpness sill), but word had passed that the sill at Sharpness was showing 10.2m and still rising as I got into the water at Arlingham.
Now for sure the wave was a little bigger than expected. By the time it reached my position it was a foam ball of about 4 ft in height. But the power was immense ! So much so that (being a bodyboarder, with half my body actually in the water) I was struggling to breathe due to the water pressure. Not only that, but with every ripple on the water’s surface in front of me I was taking air, just like a powerboat , which was also knocking the wind out of me.
I had a decent ride (of about 3 km) then of my own volition, when the chance arose, I turned over the back of the wave and headed ashore , thoroughly exhausted.
With only about half a metre of extra water, the power within the wave had increased massively.
That was the only time I ever got to ride the bore with an added storm surge.
Thanks for this insight, Neil! And your previous input. Since you ask, your previous comments were 9 months ago. A normal gestation. Our daemon considered you a new arrival to be (as in such cases) held back for approval! (I don’t remember having that choice when our new arrivals arrived)
Hi, been a year or 5 since last posted but I came across this relating to history of volcanic science which I thought might interest some. Apologies if already posted
https://www.journals.uchicago.edu/doi/10.1086/733147
Really interesting behaviour at Sundhnúkur right now- the previously “main” vent has almost completely shut off while the “pulsing” vent has seemingly taken over most of the lava output, creating a nice little cascade.
Iceland Explorer (former “Gutn Tog” during Fagradalsfjall) has visited the eruption. He stands on the western steep slopes of Fagradalsfjall’s Fjell and does a helicopter tour: https://www.youtube.com/watch?v=SBBj6xU5tdg
So it has become a Tourist Eruption … mainly for native Icelandic tourists. The lava runs towards Fagradalsfjall now and builds an inland (lava) river delta like Okavango Delta https://en.wikipedia.org/wiki/Okavango_Delta
The “room meters” are rising, now the eruption has the second highest volume since December 2023:
Eldgos 7 = Fire gush 7 is the current eruption. Iceland prefers native expressions for foreign words, but also English allows the use of Germanic words (“fire gush” for eruption) that are more close to Icelandic expressions.
“Deformation measurements in the Svartsengi area show minimal daily changes, suggesting that magma inflow into the accumulation zone beneath Svartsengi remains consistent with the outflow from the eruption.
Based on measurements taken by the Icelandic Institute of Natural History, the average lava flow rate was approximately 11 m³/s from November 23 to 28. Based on SO₂ measurements from yesterday, the flow rate was estimated to be 7–8 m³/s. Current lava flow is roughly estimated to be 5–10 m³/s.”
https://en.vedur.is/about-imo/news/eruption-begins-on-the-sundhnukur-fissure-swarm
I scrolled back on one of the MBL feeds to watch this. Amazing how the two vents traded places and then traded back to the “main” vent a little less than 2 hours later. I wonder if it’ll happen again, and what the reason for this behavior may be.
In the original Fagra I eruption, the cones all started out as doubles, with one sibling over time exterminating the other.
Since it’s boring as heck out here in California while we patiently wait at least another few weeks for rains/snow to return (though we’re now well into our rainy season, many places in SoCal have had less than 0.10″ of precip since last Spring, while others in NorCal got record rainfall ..20-25″ in some locales from a 4-day AR event last week), wandering minds are asking life-changing questions…such as:
1. Anyone willing to venture a guess as to how many scoria cones/vents have been formed on the RP since the initial lava flood at Fagradalsfjall? My guess is several dozen.
2. Also, I wonder if any of these new cones will reinvigorate, or are all monogenic? My guess is the latter. But if one did reinvigorate, what would that indicate regarding the lava-feed mechanism(s)? Would a reinvigorated cone indicate it’s sitting on top of a discrete conduit instead of from a dike ripping open?
3. Iceland should have a contest to name each new mountain/hill/cone…maybe a good exercise for getting the school’s involved? Winners get the credit for the name and a free pass to Blue Lagoon?
4. What are the local customs regarding how/when names are given out for new mountains/volcanoes? And who/which agency has the final say?
5. What is the technical term used for an emerging new volcano where no preceding activity existed? Volcanogenesis would be the obvious choice.
An important difference between Fagradalsfjall and Svartsengi is altitude: Fagradalsfjall 200-400m above sea leve; Svartsengi ~80m above sea level. If the hills of Fagradalsfjall were only 100m high, the eruptions 2021-2023 had been much more spectacular.
Before reading this piece I must say that I love your piece about Barren Island. I haven’t been aware until now that the Sunda Trench is so long reaching up far north.
As there is a spreading centre there in the Andaman Sea a mantle plume and a tiny Andaman Iceland 😉 should be discussed beside the subduction you mentioned. ?
Concerning Iceland itsself I saw a nice picture in the Atlantic mag (pic number 10):
https://www.theatlantic.com/photo/2024/11/photos-of-the-week-doo-dah-horse-play-cloud-falls/680836/
Beautiful graphs and pictures too in the Barren Island piece. I adore the photograph of the mangroves. These trees can also be seen in abundance 1000 km further north in the Sundarban National Reserve (a wetland belonging to Bangladesh and India at the Ganges Delta), home to one of the most endangered mammals on Earth, top predator
Panthera tigris:
“(Bristol itself is on a different river, the Avon)”.
It should certainly be noted, that this Avon is only one Avon. Some call it Bristol Avon for that reason. Another River Avon is the Warwickshire Avon (Stratford-on-Avon), a third one the Avon of Wiltshire and Hampshire and a fourth one the Devon Avon. The latter can be adventurous near Kingsbridge as at low tide in can be crossed via a tiny street to take a shorter road to Bigbury-on-Sea. There might be more of them.
I was wondering why so many Avons and found out that Avon in a way isn’t even a name, but just a celtic word for river.
Corncerning that big flood it seems to have happened in a period with great floods on the Eastern shores of the Atlantic Ocean (i.e. Marcellus Flood, De Grote Mandräke between 1300 and 1650).
That doesn’t seem to be the first time as the Dogger Bank disappeared about 5.500 BC
Many names in the west have Celtic etymology. The River Exe is an anglicised form of Isca, meaning water, which also gives it’s name to the old Roman city of Exeter. Isca Dumnoniorum (water of the Dumnonii). Also, any name with combe, comes from cwm. Then you have Wookey Hole Caves which comes from Celtic, Viking (Old Norse) and Old English, all with the same meaning.
Yes, thank you very much.
I havent watched much for a few years, the two vents seem to alternate with each other. On Sandholl cam, the left vent is more obvious but sometimes just shuts down and the right taller vent fountains strongly for a few minutes before the left vent reactivates. The way they actually shut each other down though is really interesting.
Compared to disasters like these
https://en.wikipedia.org/wiki/1970_Bhola_cyclone
the loss of human life with adequate warning time (neglected before the Aare Flood) in the Bristol Channel area would rather be peanuts I guess, the material loss higher though as the Bengal Bay people are poor.
@Albert, in case you have never written about this possible heritage of Ocean Tethys – I’d be very interested:
https://www.livescience.com/planet-earth/rivers-oceans/indian-ocean-gravity-hole-the-dent-in-earths-gravitational-field-created-by-the-death-of-an-ancient-ocean
For folks interested in the Bengal Bay I can also recommend this article about a hidden Grand Canyon, SoNG, the “Swatch of No Ground”:
https://www.sciencedirect.com/science/article/abs/pii/S0967064502006161
Ideas: “The formation of the SoNG has been subject of speculations. LaFond (1958) suggested that the canyon may have formed (1) as result of a fault which is connected to faults in Assam, (2) by incision due to mass-wasting processes and turbidity current generation or, (3) by incision due to river erosion during glacial periods.” From link.
Parts of Iceland now have severe weather. F.e. the rivers Selfoss and Ölfusa have got ice dams which let water level rise: https://www.mbl.is/frettir/innlent/2024/11/30/vatnsyfirbordid_heldur_afram_ad_haekka/
Some wonderful aerial drone footage here from Just Icelandic. The aerial views capture very well the layout and topography of the Reykjanes Peninsula. Please see https://www.youtube.com/watch?v=F2PLkz-WoQc
New post is up! Tallis rounds the world
https://www.volcanocafe.org/flat-earth-and-the-rise-of-anti-intellectualism/