In Hawaiian folklore, Pele is vengeful and unpredictable. Her habitation is well known: Kilauea leaves little doubt about where Pele lives. But you never know where she may appear next. She shares this habit with Kilauea. It has a clear summit and all the action stems from there. But where the action will be next is anyone’s guess. Over the years, as for a change she was immovably from the same location, this was forgotten about. But in recent weeks it has become abundantly clear again, as within days she went from a stable-looking dual-eruption site to draining these two completely and turning the magma on distant Puna.
It was always changeable. Below, a table of eruptions is reproduced, copied (with minor fixes) from https://www.soest.hawaii.edu/GG/HCV/kil-hist.html of the Hawaii Centre for Volcanology. From 1790 to 1924 there was (perhaps intermittently) a lava lake at the summit. This drained in 1924 with a significant explosion. From 1924 to 1955 there were mainly brief summit eruptions. In 1955 the heavens opened on Puna, and since then most of the activity has been in the eastern rift zone, from 1983 almost continuously at Pu’u’O’o. Since 2008 there was activity both there and at the summit. But over the past years the flow rate from Pu’u’O’o had bene declining, and the lava more rarely reached the ocean. Mid April this year, a blockage developed at Pu’u’O’o and lave began to back up, first inflating the magma reservoir at Pu’u’O’o and later also at Kilauea. On April 30 the rift opened and magma began to flow into the rift. The Pu’u’O’o eruption was abruptly cut off. And on May 5, Puna was hit again, right in the middle of a new housing development that wasn’t there last time Pele came looking. One can argue whether it was a folly to build on a known rift. But in Hawaii, you take your chances. Even Hilo or Kona aren’t safe.
|Year||Date of Outbreak||Duration (days)||Location|| Volume
|1750 (?)||East rift||14,200,000|
|1790 (?)||East rift||27,500,000|
|1790||November (?)||Caldera||No lava flow|
|1832||Jan 14||Short||East rim of caldera||(?)|
|1840||May 30||26||East rift||205,000,000|
|1868||April 2||Short||Kilauea Iki||(?)|
|1868||April 2 (?)||Short||Southwest rift||183,000|
|1877||May 4||1 (?)||Caldera wall||(?)|
|1877||May 21 (?)||Keanakakoi||(?)|
|1884||Jan 22||1||East rift||(?)|
|1894||July 7||4 (?)||Caldera||(?)|
|1919||Feb 7||294||Caldera||25,200,000 (?)|
|1919||Dec 21||221||Southwest rift||45,300,000|
|1922||May 28||2||Makaopuhi and Napau||(?)|
|1923||Aug 25 (?)||1||East rift||73,000|
|1924||May 10||17||Caldera||No lava|
|1954||May 31||3||Halemaumau and caldera||6,200,000|
|1955||Feb 28||88||East rift||87,600,000|
|1959||Nov 14||36||Kilauea Iki||37,200,000|
|1960||Jan 13||36||East rift||113,200,000|
|1961||Sept 22||3||East rift||2,200,000|
|1962||Dec 7||2||East rift||310,000|
|1963||Aug 21||2||East rift||800,000|
|1963||Oct 5||1||East rift||6,600,000|
|1965||Mar 5||10||East rift||16,800,000|
|1965||Dec 24||<1||East rift||850,000|
|1968||Aug 22||5||East rift||130,000|
|1968||Oct 7||15||East rift||6,600,000|
|1969||Feb 22||6||East rift||16,100,000|
|1969||May 24||867||East rift||176,700,000|
|1971||Sept 24||5||Caldera and southwest rift||7,700,000|
|1972||Feb 4||455||East rift||119,600,000|
|1973||May 5||<1||East rift||1,200,000|
|1973||Nov 10||30||East rift||2,700,000|
|1973||Dec 12||203||East rift||28,700,000|
|1974||July 19||3||Caldera and east rift||6,600,000|
|1974||Dec 31||<1||Southwest rift||14,300,000|
|1977||Sept 13||18||East rift||32,900,000|
|1979||Nov 16||1||East rift||580,000|
|1982||Apr 30||19 hr||Caldera||500,000|
|1983||Jan 3||April 30, 2018||
|2018||May 5||on going||East rift, Puna|
One can argue that 1955 was the year of change. This was when Pele became bored with the summit and became infatuated with the eastern rift.
Kilauea has shown three basic eruption mode. The touristy one is that of minor but photogenic activity at the summit, as between 1790 and 1955. The awkward one is the rift eruptions, as have been the bane of Hawaii since 1955. And the dangerous one is explosions from the summit. Those appear to have happened in the 200 years or so before 1800, culminating in the disaster of 1790. That year, the summit exploded just as a group of people traveled past. The explosion was the result of a violent intrusion of groundwater. First, there was a thin deposit of wet ash in which the traveler left footprints. Next, the eruption column, which was seen from 90 km away, dropped small stones (lapilli) in it. Finally, the collapsing column, or perhaps a new eruption caused a pyroclastic flow of steam and ash, covering the area west of the summit, with many casualties. It is easy to overlook the explosive nature of the summit. This was the memory that gave Pele such a reputation.
But that was all forgotten, and in case, 1790 was before the occupiers came from the west. Puna, in the eastern rift zone had seen no activity since 1840. Apart from an explosive event in 1924, Kilauea had bene well behaved. Mark Twain may have written his famous depiction of Kilauea’s hell, but it was a hell fit for tourists. It was as if Kilauea had forgotten about it, just like the people had forgotten about Kilauea. The area had become a lush rain forest. This was many people’s idea of paradise. The tropical garden would grow anything that could see some soil. I have not had any sweeter pineapple than from this region. Hawaii was never a rich area and paradise can make for a harsh living, but living here must have made it seem worthwhile.
The summit had also gone to sleep. But after 18 years of quiescence, there was another summit eruption in 1952. The summit now began to inflate, in spite of a brief eruption in 1954. This was before Pu’u’O’o and the magma had nowhere to go.
What happened next is described in considerable detail in an article from USGS. To briefly summarise, small earthquakes began to be measures in Puna in the second half of 1954. There has also been earthquake activity at the summit, but nothing in between. That may seem strange, for how had the magma managed to get from the summit to Puna without disturbing the region in between? The best way to avoid earthquakes is to have the liquid already in situ, as flowing magma does not create earthquakes: that is the shattering of the rocks. In hindsight, the magma had been finding a way long before, perhaps during the 18-year hiatus. The reservoir that 30 years later was going to create Pu’u’O’o was already there.
The following video shows the severe health and safety procedures which were in place during the eruption.
In February 1955 the earthquake count rose, and in the morning of Feb 28, the first fissure opened up. This was east of where is now Leilani, and which was forest at the time. The first eruptions were not particularly vigorous, with fountains tens of meters high, but the fissures extended eastward. After some interruptions and new beginnings, the fissures reached Kapoho village. Now the fountains were over 150 meters tall. The lava spared the main town, but the road was cut on either side of the now isolated town. (Kapoho’s reprieve was temporary: the town was later lost in the eruption of 1960.)
The eruption paused on March 7. Now activity shifted westward, up-rift, where new fissures opened on what is now west of Leilani. The road here was attacked in images that look eerily similar to 2018. The eruption spread and became vigorous, with fast flows cutting the coastal roads.
By April 8 the lava flows had ended, but there were still occasional outbreaks from spatter cones. In May, there were some new flows coming from Ilewa crater which did damage. On May 26, after 24 different vents had erupted with at least four major lava flows, activity abruptly ceased. It left a community shaken and farms and houses destroyed, but no lives were lost. It did change behaviours and beliefs: the number of food offerings made to Pele greatly increased during and after the eruption, although in a sign of cultural change, the traditional gifts of breadfruit, bananas, pork and tobacco were now often presented in Christmas wrappings.
USGS mentions that the early 1955 lava was unusually differentiated, suggesting it had been in local storage for a considerable time. Kilauea only ever produces basalt, with MgO ranging from a low of 7% to a maximum of 20%. But the early 1955 magma had MgO as low as 5%, a sign of crystallization over time. Had it been in local storage since 1840, perhaps? This is similar to the current eruption which so far has pushed out old magma. The old material must have cooled considerably over time, but apparently was reheated by the new magma. The opening rift pushed out the old material, but also turned it back into eruptable magma. Perhaps this had begun in mid 1954, and as the old magma slow re-melted, it opened the rift. It must have been a slow process, and perhaps with modern instrumentation HVO could have seen it happening. Later in the eruption the new magma arrived from the summit, and this was also shown by the deflation at Kilauea. Whether the change in lava composition is because of mixing with the new magma, or because of stratification in the local storage, remains hotly disputed.
So Puna is not just a recipient of magma that is pushed down the rift. It has its own storage underground. Drilling at the Puna geothermal plant has even found dacitic magma, at a depth of 2.5 km, which had differentiated (and cooled) even longer. Kilauean magmas can only produce a few per cent dacitic magma, so by the time this has happened there is very little magma left. But there are things happening underground and Puna is far from passive. The eastern rift extends beyond the coast, and at times has erupted directly into the ocean. The lavas here show a range of compositions, also with evidence for storage in the rift zone.
How long had the magma been in storage? This has been studied with radioactive trace elements, thorium and radon. With surprising conclusions. The magma had not been left by the 1840 eruption. The minimum storage time was 550 years! And it may have been as long as 2500 years. It seems that the 1955 eruption was based on events that pre-dated even the Hawaiian’s occupation of the island. Pele had been waiting for them. The trigger came from the summit, but the ammunition had been made ready longe before.
Sp how about the current eruption? When it is sated to have pushed out 1955 lavas, which lavas do they mean? And why is this such a wimpy eruption compared to 60 years ago?
The lava that is pushed is likely a mixture, as that is what 1955 produced. Interesting is that the current eruption was focussed on Leilani, which is exactly the area skipped in 1955. In a way, this was the region where 1955 was never finished. But why is there so little vigour? It is a good thing for the local population, apart from those people who still have lost their homes, through no fault of their own. The Earth too does terror.
The difference with 1955 is up-rift. Pu’u’O’o has been providing the east rift zone with a safety valve for the past 30 years. The pressure in the rift never build up, and presumably it has only been in the past year or so that any flow-through to the eastern rift restarted. The current eruption is running on fumes. The Kilauea summit reservoir is replenishing the rift and adding new pressure, but whether this is enough remains to be seen. 2018 is not 1995. We have television, mobile phones, youtube – it is different world. And Kilauea has developed a safety habit. But now, whilst the world seems to be returning to intolerance, Kilauea may be changing. Puna perhaps is petering out – but Kilauea could be starting a new era of explosions. Time will tell.
Albert, May 2018