Extraterrestial volcanoes I: The lava outflow channels of Mars. Evidence from morphology.

There are eight planets in our Solar System. Of the eight planets three of them have silicate, probably active, volcanism. Mars, Earth and Venus. It is very insightful to compare the volcanism between these three planets in order to find out more about how Earth’s own volcanoes work. Yet I find that extra-terrestrial volcanism is still misinterpreted despite the wealth of data that we have. Some popular ideas are still running around which I think could be disproven easily. Particularly the theory of how the Martian outflow channels were formed.

The Mariner 9 was the first spacecraft to orbit Mars. This was in 1971. After a global dust storm cleared away it was finally able to take pictures of the planet surface. The images it took revealed the existence of giant canyons, and river-like features. Valles Marineris, Ares Vallis, Kasei Valles and other landforms which were interpreted as having formed due to flowing liquid water. But it has been a while since then. Nowadays we have a global mosaic of the surface of Mars, at a resolution of 6 meters per pixel, taken by the Context Camera of the Mars Reconnaissance Orbiter. This is incredible detail that allows to look closely at these outflow channels and know more about how they formed.

First I should clarify that there are two different types erosive structures that have been attributed to water. One of them is the valley networks. The valley networks occur mainly in the Southern Highlands of Mars and are usually 4 billion years old. They have features like those of river drainage basins on Earth. To me they look water made and clearly have nothing to do with volcanism, could have been rivers of liquid water. Although the idea of water or carbon dioxide ice glaciers should also be considered.

Example of a valley network in the Southern Highlands of Mars. THEMIS daytime infrared mosaic of Mars as viewed in Google Earth.

The second type is outflow channels. These are much younger, some of them only a few millions of years old. They are found close to volcanoes, most of them being concentrated in the Tharsis and Elysium volcanic provinces. They lack sedimentary deposits like deltas or ripples. The channels initiate abruptly from a chasm or depression in the ground which has led to think that they were formed in huge outbursts of groundwater contained in aquifers under the surface. It is also remarkable the size reached by some of the outflow channels. The largest one is Kasei Valles, a canyon with a length of 1600 km, a width of up to 400 km in places, and a depth of up to 3 km.

One of the main problems with the liquid water hypothesis for outflow channels is that Venus has identical valleys to those of Mars. It not possible for liquid water to exist on the surface of Venus. Additionally the youngest canyons of Venus always are seen to channelize lava flows, and they tend to emerge from radial and circumferential fractures around volcanoes.

Head of Kallistos Vallis in Venus. Magellan radar image seen in Google Earth.

Unnamed incised channel in Venus, near the tectonic feature called Muta Mons. Magellan Image seen in Google Earth.

Several outflow channels issue from radial fissures of the volcano Elysium Mons. The morphology is identical to the other examples in Venus. Daytime infrared global map of Mars in Google Earth.

I’m here to explain why there is morphological evidence, unambiguous evidence I’d say, that the outflow channels of Mars are lava made. Not water but lava. The result of giant flood basalt eruptions. I’m not the first person to say so and for example the geologist David Leverington has done some great articles about this aspect. This post will focus only in the morphological evidence, so for a full discussion on why the outflow channels were made by lava, and also why the groundwater hypothesis has many problems, I will leave one of his articles here:



The formation of fossae and catenae

There is something important which is often overlooked and is that lava erosion may occur not only along lava channels, but also along dike intrusions. Magma flows underground through intrusions which for simplicity I simply refer to as dikes, although there may be other morphologies like sills or cone sheets that are involved. In Hawaii, in particular, there exist many features similar to the so called fossae and catenae of Mars, only much smaller, that are related to dikes and their erosive processes. Volcanism on Mars is of a huge scale so that it does the same landforms only bigger in scale.

In the island of Hawaii, during the eruption of Mauna Ulu, in 1969, the pit crater Alae had been filled with a rootless lava lake. Rootless means that it is not fed from below. The lake formed from lava that erupted out of Mauna Ulu and then flowed downslope towards Alae where it collected passively. On August 4 the lake catastrophically drained into a dike intrusion. The lava lake emptied in half an hour at a flow rate of 5500 m3/s. Spectacularly high for terrestial lava flows although probably insignificant compared to Martian effusions. The lake drained through a dike along which erosion took place, a substantial amount of rock was carried away with the flow leaving a chasm that was 10 meters wide, up to 70 meters deep, and 800 meters long.  Similar features are also formed when Nyiragongo volcano in the Congo has its typical catastrophic lava lake outbursts.

What is also interesting about this event is that it was rootless dike intrusion. It was fed from a surface lava lake. Lava flowed back into the ground making a dike that was probably very shallow, just skimming the surface, as shown by the fresh lava that could be seen in the bottom of the chasm. If there had been someone looking into the fracture while the lava lake drained it would have probably been able to see the raging torrent of lava. I think that rootless dike intrusions might be extremely abundant in Mars from what I have seen.

Chasm-like feature formed during the draining of the Alae lava lake which at a small scale resembles Martian fossae. Photo from USGS.

Later in the Mauna Ulu eruption there was another demonstration of the erosive power of lava/magma. Magma flowing along a dike from the summit of Mauna Ulu to Alae gradually ate away the rock and created a series of pit craters which later merged into a continuous trench 40-60 meters wide.

Lava erosion forms a small canyon along the magma pathway between Mauna Ulu and Alae. Photo from USGS.

Portion of Olympica Fossae in Mars. The canyon here is 1500 meters wide and 200-300 meters deep. It is very similar in structure to the trench of Mauna Ulu, just 30 times bigger in width. Mars likes to do huge eruptions. CTX mosaic in Google Earth.

Other landforms commonly seen in the surface of Mars are the catenae. These are chains of pit craters often related to grabens, and from which lava can sometimes be seen to emerge. On Earth structures similar to the catenae of Mars occur along eruptive fissures and seem to be linked to dikes, possibly another form of dike erosion like fossae, but discontinuous. Certain portions of the dike may widen due to erosion so that the roof collapses into the magma, the rock is carried downstream, then the roof continues to collapse incrementally making a pit crater. Such collapse structures are often located at the upslope end of an erupting fissure that lasts long enough for the erosion to show up.

The Great Crack. Chain of pits and fractures that fed the 1823 eruption of Kilauea. From Google Earth.

Two collapse craters align with an eruption fissure. Lava erupted within the right crater. The location is Alayta volcano in the Afar Depression. Capture from Google Earth.

Slopes of Pavonis Mons showing an area of eruptive fissures, fossae and catenae, which are circumferential to the summit of the volcano. CTX mosaic of Mars viewed in Google Earth.

Interpreted map of the above image.


The creation of an outflow channel

Lava is known to be able of eroding into the bedrock it flows over. One of the probably many examples that exist on Earth is the Kazumura lava tube in Hawaii. This is the longest lava tube know on Earth, and formed during overflows from the summit of Kilauea in the 15th century. Speleologists have descended into the Kazumura cave. The lava tube shows meander migration and downcutting into the bedrock, similar to processes that take place in rivers. Some meanders migrated up to 9 meters downstream. Certain parts of the lava tube with a steeper slope were eroded backwards, this back-cutting resulted in the formation of lavafalls, and at the bottom of the cascade the turbulent flow created large pools which expanded laterally through erosion making a wider passage. So yes, lava erosion happens. It is thougth to be due to lava melting the rock that it comes into contact with. On Earth it is a more subtle process and only observed upon close inspection of lava tubes or channels. On the other hand Mars, with its gigantic eruptions that are far more intense, longer, and more voluminous than those on Earth, it can erode spectacular canyons.

The outflow channels have been traditionally attributed to water. Outbursts of water from aquifers. However there are some characteristics of outflow channels that are not consistent with water. First is that there are no sedimentary deposits, there are no deltas, nor ripples, nor any sort of sedimentary structure that is characteristic of flowing water. And second they have features that could have only been done by lava. As an example I will use Olympica Fossae, a 650 kilometres long outflow channel that switches between channel and dike transport. It is located in the volcanic province of Tharsis and it maybe emerges from a fissure of the volcano Alba Mons.

Right below is an image of Olympica Fossae. In this particular spot the canyon is a system of braided channels that reaches 7-8 kilometres wide and 500 meters deep. Here the channel has just emerged out of the large fossa to the right. There are a series of other small fossae visible along the sides of the valley. It doesn’t appear possible that water could have made structures such as these, however lava would. These linear features might be rootless dike intrusions which propagate from the lava channel outwards and have eaten away the rock closest to their source. It can also be appreciated that two smaller channel systems emerge out of these fossae. Lava that was flowing down the main, master channel would have entered the rootless dikes and emerged from fissures located at slightly lower elevations.

Olympica Fossae. CTX mosaic from Google Earth.

Some of the smaller streams from braided channel network can be seen to flow away from the rest and turn into normal looking lava flows. That is where you clearly see that the outflow channels are lava rivers which have been active for so long that they have melted down into the bedrock, farther down however they become normal streams of lava. For example this is a flow that separated from the braided network shown in the previous images, it is no longer erosive and instead has the typical appearance of sheet aa flows like those seen in intense volcanic eruptions:

From Google Earth.

Right below you can see the big picture. The outflow channel in reality is only a small portion of a much larger flood basalt eruption. The eruption of Olympica Fossae I estimate may have been around 3,000 km3 of basaltic lava, perhaps even more since there is a possibility that Olympica Fossae was just one of multiple erupting fissures in the area. The total length of the flow seems to be 1900 kilometres, but only the upper 800 kilometres have experienced significant erosion 

Map of Olympica Fossae. Green indicates fossae and catenae, presumably dikes. Orange shows normal lava channels. Red indicates lava channels that have eroded into the bedrock. Yellow are normal lava channels that probably formed in the eruption but are so far away from the fissure that they cannot be traced up directly to it. Pink represents the master lava channel with has downcut hundreds of meters into the rock. Viewed in Google Earth.

At the start of the eruption lava poured out of multiple fissures making many lava streams. The streams separate and merge again in fascinating patterns and shows that the whole system of channel was active at once. Later activity focused into fewer channels and eventually was limited to the master channel which cuts deeply into the ground. The transition between erosional and non-erosional lava channels is very well visible.

Map of the upper part of Olympica Fossae. Green indicates fossae and catenae, presumably dikes. Orange shows normal lava channels. Red indicates lava channels that have eroded into the bedrock. Pink represents the master lava channel with has downcut hundreds of meters into the rock. Viewed in Google Earth.

There is one location where the master channel goes into a dike and travels 170 km through a fossa before reappearing again farther south. The master channel and the subsidiary streams seem to have a continuation downslope across the fossa as normal lava rivers. It can be seen that in the early phase of the eruption the main channel started a rootless dike intrusion which then diverted the flow of lava 170 km away, changing the path followed by the lava.

Map of the lower section of Olympica Fossae showing the 170 km jump of the lava channel through a dike. Green indicates fossae and catenae, presumably dikes. Orange shows normal lava channels. Red indicates lava channels that have eroded into the bedrock. Pink represents the master lava channel with has downcut hundreds of meters into the rock. Viewed in Google Earth.

Location where the lava stream was diverted away by a dike during the course of the eruption. The master channel still had not started to erode into the ground when this event happened. Viewed in Google Earth.

Thus there is obvious evidence that Martian outflows valleys were created by giant floods of lava. So it is time to discard the idea of groundwater outbursts. There is just better information now. When inspected closely it shows the true lava-made nature of outflow channels.

Just to finish here are some images of the youngest outflow channels in Mars, those of Marte Vallis. The last eruption of Mars took place perhaps as recently as 3 million years ago, it erupted from Cerberus Fossae and created the Athabasca and Marte Vallis.  Dark material is rugged aa-type lava. Bright material is either smooth pahoehoe-type lava or old Martian rock. If you look closely you can appreciate the broken plates of black aa lava carried by the stream, and where they separated from each other molten material rose up from below making a smoother surface of pahoeheoe. The convoluted braided streams of aa lava which at places merge into a spectacular 100 kilometres wide river of lava, can be seen to have excavated banks against the obstacles it encountered. Erosion is slight but noticeable. This was a much more brief eruption than the one that made Olympica Fossae, however it was superior in intensity and volume.

Marte Vallis. Image from Google Earth.

Marte Vallis. Image from Google Earth.


Relevant links

Development and morphology of the Kazumura Cave, Hawaii.

Volcanic rilles, streamlined islands, and the origin of outflow channels on Mars

Mars interactive maps.

286 thoughts on “Extraterrestial volcanoes I: The lava outflow channels of Mars. Evidence from morphology.

  1. 212 quakes of shallow depth in Pozzuoli bay since October, gas emissions increasing again, and slow uplift has continued.

  2. I go to start to worried….. very near.
    2.0 mbLg E FASNIA.ITF 2021/11/13 23:08:28 33 +info

    • Where do you live again? Canary Islands?? 😮
      I remember Luis being from Portugal, but I forgot about you.

      • Oooo boi, that is extremely close to the eruption! Are you expecting problems upcoming then?

        Have you already been to La Palma since the eruption started?
        Or are you respecting the Palmeras/Palmeros asking not to do volcanology tourism?

        • 145 Km from here. I the eye put if sudenly the earthquake activity raise. Here we have the 2004 unrest when someone get in panic on the northwest side of the islands to a new volcano / teide was incoming to erupt. On the last years, some small unrest has appears and waiting about happens.

          No, I dont go to the la palma. I have some parents with have familiars living on los llanos de aridane, worried by the situation with the volcano.

    • How many cubic meters have been erupted now ?

      Soure perhaps small compared to Leilani and Holuhraun was 1,5 km3

      But I guess 350 million cubic meters of lava now from the Canary Eruption

  3. Wow the eruption at Kilauea is really overflowing now, lava breaking out of the sides of the spatter cone and the vent is more open. There was deflation after the high point before but the eruption has not declined with it. Maybe the vent is disconnected from the crater wall now, with lava erupting from the gap?

    I guess we will have to see if the SO2 has increased.

      • Looks like maybe the spatter cone is detached from the wall now, the vent inside the cone is still erupting and looks stronger than before and there are two big lava flows erupting from both sides of the cone where it contacts the wall of the caldera. Hope there are some new pictures soon 🙂

        Maybe my educated guess of a new magma pulse coming up based on a couple of deep quakes the other day, could have been correct 🙂

    • Something weird too, the CALS station on the boggest downdropped block, about a week ago moved up and down by about a meter 3 times, and the same signal but smaller was also seen on the tilt at Kilauea Iki and at HVO/Uwekahuna. It is as though the whole summit if Kilauea was affected centered on the caldera.

      I remember seeing some similar signals back just after the 2018 collapse, they look like instrument errors but the fact 3 instruments several km apart all show a near identical pattern shows it is real. 1 meter of vertical ground movement in a day that is a significant detail.

  4. Then We haves Baltis Vallis on Venus, a
    6800 kilometers long and 10 km wide lava channel system : )

    Since Flood Basalts caused many mass extinctions on Earth Its entirely possible that Earths Flood Basalts s where acually Marsian and Venusian in scale. It woud be hell on Earth If it happens again.

    Earth haves plenty of Internal Heat left.. althrough nothing like that on the horizon for now.

    Souch flows coud have erupted many Holuhraun even many Laki volumes per minute!
    If you look a similar preserved flood basalts at Mars, like Athabasca Valles Lava Megaflood 🙂
    Althrough No humans where around in the Trissaic so We will never know really. But Yes Laki and Eldgja where Impressive shows anyway


    • Need a Tardis to go back and see the extent of flood basalts – from a safe distance of course!
      I’d also go forwards and see what happens with continental configuration…

      The Oceanus Procellarum flood basalts on the moon was a large event, believed to be caused by a massive impact. Only 1 billion years old too, which was far younger than expected. How much of the moon’s core is still liquid?

      • Still liquid deep down But the Moon is so small it have cooled alot..

        Moons entire mantle have now shut down and become a solid inactive litosphere.

        Moons eruption days are long gone really

        • Do you think another large impactor could change that though?
          I imagine there will come a point when it really does shut down for good.

        • A normal asteorid wont heat up the moon much

          You needs a pluto sized rocky object that hits at very very high speeds To re – melt the moon

    • This won’t happen. If you take the region from the Afar Triangle to Nyaragongo or even prolong it to Réunion you see a row of huge volcanoes. But they don’t erupt at the same time. You can also take the cases of Mazama, Toba and Thera: They erupted well spaced from each other.
      Or you take Iceland, a small Igneous Province. They erupt more often, but not at the same time. It’s Earth. Crust, when under stress, has to rearrange and at some point does this again.

      So, all these extinction scenarios are too simple. Those extintion might have gone on for 1 or 2 million years, and there were other factors like changing climate, changing currents, changing food, different enemies maybe. So it looks like a short thing, but must have been longer and more complex.

      The easiest extinction is the one caused by Homo stultus. He goes out with ships i.e. and introduces rats. They are still active. Gough has a real problem, but there are plans to kill those rats which has been done before on another island.

      Mars and Venus are different.

      • Another small example. The fossils they found in Hell Creek have possibly died in an instant flash flood. That is the minimum of what existed, most animals haven’t fossilized, and most fossils cannot be found being under the Himalayas i.e. or on ocean floors, where no single skeleton was found around the Titanic. That Hell Creek Found is between 65 and 66 million years old. The age cannot be set up by the day, month and year.

      • You are so wrong .. with this
        Saying LIP events where like normal eruptions

        Flood Basalts can be gigantic, some individual flows of the CAMP where many Vatnajökulls big in volume and erupted as uniform sheets, signs that it went really fast.

        The old dykes from these are many 1000 s of km long. Souch lava flows flowed thousands of kilometers over Pangea. The gas coud kill from 100 s of kilometers distance. So it can get much bigger than Laki and Eldgja.

        What you see on Mars is what these flood basalts where like on Earth

        But the current extinction is indeed caused by human activities

        • Jesper has a very good point here, and he is quite correct.
          A LIP is something nobody wants to see at full swing.

        • Carl Rhenberg

          I wants To see one
          But you know How I am.. I wants magmageddon

          I Only haves Hawaii and Iceland to enjoy 🙁

          I wants it bigger!
          I wants mega flood volcanoes

          Althrough Hawaii is my favorite place 🙂

        • Humans have been causing extinctions for a long time.


          At least we have reached a point where people in the more comfortable parts of the world realise you can’t just kill wild creatures indefinitely. But when the journalist Tim Butcher retraced Stanley’s 1876-77 journey from Lake Victoria to the Congo River in 2006, he found a jungle denuded of wildlife by people desperate for food.

      • Also the effects of CAMP is well seen in geological records even if it was a very very brief event with 5 pulses

        CAMP LIP formed just before Pangea started to split

      • CAMP was probaly the largest land flood basalts since multicellullar life began
        201 million years ago

        Needs a time machine

      • Chicxulub was disasterous too. You haves a 14 km wide lump of rock and Iron that gets in at 40 km a second

        Thats an enormous ammount of kinetic energy
        A bowl of Earths crust 180 km wide and 40 km deep vaporize togther with the asteroid.

        Earths crust behaves like you throw a stone into a puddle during souch impact
        Ritning rings and central peak. And the crust bounched up Leaving an Impact Melt Province

        An 20 000 C of vaporized rock ejecta woud rise up from the crater just after impact, perhaps 50 000 km3 of materials where sent on Ballistic Reentery Trajectories

        All that Chicxlulub ejecta will dump its energy in the atmosphere as it comes in as trillions of meteor falls, turning the skies furnace hot over the Northen Hemisphere .. There is a global soot layer from the KT
        So the Worlds forests burned.

        But How extensive the atmospheric Firestorm was is debated. But North America was turned to ash by Chixlulub, everything is burned down in KT boundary in America

        • Jesper,
          I’m not saying that flood basalts weren’t terrible, not to speak of a large meteorite.
          But: Some survived and evolved, that’s evolution. The similarity in forms is breathtaking.

          I’m just saying that we won’t have that for the time being. Also Deccan in India and Kerguelen was a big continental mass breaking away. It might happen when South West Africa breaks off, but Jesper: That’ s in some tens of millions of years, maybe 50.
          Besides there are things that possibly were not yet looked at yet: Large Calderas, really large ones are old. Younger ones are smaller. And Iceland is smaller than the Siberian traps. Earth might be like a Virus. A virus when it kills everybody can’t replicate, so a virus mutates. There might be some intelligence in nature that we will never understand. A sort of learning we don’t know.

          Try to wish for smaller things. Look at the people in Paris, how beautiful they were painted just like decoration:

          I sometimes wished I could walk there and then with them just for a day. It’s not possible either, but it wouldn’t hurt anybody.

      • If you where in European Archipelago When Chicxlulub happened You woud feel the seismic vibrations after the impact.

        You are too far away to be incenirated by the initial impact flash

        But after an hour the ejecta woud start to come in as shooting stars, trillions of shooting stars, so much that the Thermal radiation woud broil the dinosaurs on the ground. The atmosphere woud be well heated by Reentering ejecta

        I dont know How long the ejecta reentry Thermal pulse lasted from Chicxlulub

  5. Do not mind the clanking noises and the creaking carriages travelling down the road to the meadow under the large oak tree.
    Do not mind the noises of Hobbits setting up tables, and the fellow with the big beard and the pipe.

    All is as it should be in the Shire…
    For now…

    • Bravo – tremendous video. Really shows how much ash has fallen, trees still standing but half-buried in it.

    • That channel has some very good drone videos of the lava channels and such, thank you!

  6. Volcano related – human remains of found in cave on Etna.


    “Pacetto said the cave on Europe’s tallest active volcano was extremely difficult to access, and whether the man entered it voluntarily or by force, he may not have been able to escape. Police have received several calls from the public since the discovery, including from the daughter of Mauro De Mauro, a 49-year-old investigative journalist who disappeared in Palermo in September 1970 and whose body has never been found. Franca De Mauro contacted police after reading that the remains had malformations to the mouth and nose, which her father had because of an injury sustained during the second world war.

    Investigations into his disappearance followed several different leads, one being that De Mauro was kidnapped and killed by the Cosa Nostra mafia owing to him knowing the truth about the alleged assassination of ENI boss, Enrico Mattei.”

    Sounds like the cave was an oubliette, where once inside you can’t get out.

  7. Offtopic scientific question:

    Are covid PCR tests failing to detect some infected people?

    Where I live, we are currently living a big outbreak of delta variant. With a surprising lightining bolt speed, Covid came suddently, and in a few days, everyone got infected at almost the same time (before this outbreak, very few people in the region had had covid, and I was one of the very few that got covid in 2020 as the lockdown stopped the spread back then). At least two spreading events occurred: one a social event that gathered hundreds indoors, and another was a school outbreak. Both at the same time.

    So most I know tested positive and several got ill (to different degrees and especially the non-vaccinated ones, but not only). Surprisingly some people had symptoms but tested negative (days after their contact with people that tested positive and got ill)! It doesn’t make sense. (By testing I am only refering to PCR, not lateral flows)

    Some of these are people in the same household, and I know at least two stories: one middle-age non-vaccinated woman was bedridden and tested positive, but her middle-age non-vaccinated male partner tested negative and had just mild symptons. And in another household, a young vaccinated woman had mild symptoms and tested positive (after everyone is her working place also got covid) and his partner, a 60yo vaccinated man, developed flu-like symptoms and now fatigue, but tested negative (twice) to his surprise.

    And then it is the story of me and my partner. As you know I had covid last year and it wasn’t nice.
    Last week we both had exposure to covid infected people. We had at least contact with 2 unvaccinated people that tested positive and got ill (we were indoors with them without a mask). Days after this, we all got mild cold-like symptons (including a bit of cough) but we tested all negative.

    All of this is within the same village, where most are now testing positive and a significant number developped symptons, some more serious.

    It is definitively strange that some people do not test positive, despite having symptoms and exposure to covid.

    Is the PCR failing to detect positive cases?
    Does this have to do with wrong ways of self-swabbing oneself?
    Or does this happens because of low viral loads that fail to be detected?

    Any idea why this is happening with the PCR tests?

    • I should add that several of those people that tested negative but had significant symptoms, actually had high fever, some cough, and fatigue afterwards (typical covid symptoms), in addition to their exposure to people that were confirmed positive. These people are likely to have contracted covid and should have tested positive but they didn’t.

      I also know stories of people (from other regions) that on their PCR tests, first tested negative (in first days of symptoms), and later actually tested positive. And some that showed the reverse pattern, first positive, and then negative, a few days later.

      There seems to be evidence that the PCR test is failing to detect a few instances of covid.

      • Several possibilities: 1. Another virus is going around as well, that would be Respiratory Syncytial Virus as that’s present. 2. The tests aren’t “positive”, when done too early, the average for incubation is four days.

        Delta spreads much faster and on an average is less dangerous, average means that some people might suffer more. Then when you were gathering there might have been a super-spreader. The first one was Steve Walsh, he gave his name to the news, and you can google him. Last: Some people don’t get it.

      • I read some scientific literature and it clarified the issue:

        Research seems to show that PCR false negatives could be around 10-30% in real-world situations. One problem is testing too early, when the person develops symptoms but viral loads are still quite low, not resulting in amplification of the N gene. Ideally, a person should be tested 8 days after their exposure (or around day 3-4 of their symptoms).

        But soon after day 5, the virus might migrate solely to lower respiratory airways and then PCR would also fail to detect some cases.

        Self-swabbing is also another potencial problem. In the UK, people self-swab themselves. It would be more appropriate to have a qualified nurse doing this.

        • Indoor gathering now is not reasonable. I knew it would come back as children are in school. And every automn children come home with some infection.
          So, better keep some distance and only meet family and close friends. People don’t learn, too bad.
          There’s a very impressive example, and that is Sweden. From the beginning they told people to take care and how. Children were in school. They had a small problem in between. At the moment every single lockdown country has a fourth wave. Not Sweden, they have some cases, but very moderate.

          If people learnt and also were given the right messages we wouldn’t have this problem. A new lockdown wouldn’t help, because then we carry it on to the next automn. People should grow up.

          • Yes, sweden has probably handled it best, the current figures are exemplary.
            Overall, that is, socially, economically and actually overall deaths.

    • Comments made 6 months ago, when samples for pcr in UK were ONLY done by trained staff, suggest its unpleasant. Some one said it was like someone trying to hit the back of your brain through the nose.
      The reason being that adequate dose on the sample needs to be in the correct area, which is not the mouth.
      So, Irpsit, you are probably bang on the money.
      Some will have only a light viral load.

    • The tests are not 100% accurate, even if administered correctly. More accurate tests are needed.

    • Looks like the tubes are finally getting close to the ocean, the lava is way more fluid there now, actually a liquid not a mass of glowing rocks.

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