November is the anniversary of the eruption of Kilauea Iki, "Little Kilauea", but why talk about this relatively short eruption?
This fissure eruption lasted only from November 14 to December 19, 1959 ... but it produced some of the highest lava fountains produced during the 20th century.
More interestingly, some of the first measurable data from the Kilauea magmatic reservoir were collected on this occasion.
Kilauea Caldera - the crater of Kilauea Iki and the 1959 eruption, in bronze green - Doc. USGS / AVO
Kilauea Iki was born in the 15th century, during the partial collapse of part of the western flank of Aila'au due to an eruption that partially emptied the magma chamber.
Three months before its eruption in 1959, a deep seismic swarm, located 55 km deep, is recorded. In mid-September, shallow earthquakes start near the Halama'uma'u crater. Their numbers increase to around 1000 shakes a day.
On the afternoon of November 14th, the seismicity suddenly increased in number and intensity for five hours ... and at 8:08 pm, a 900 meter long eruptive crack opened on the south wall of Kilauea Iki crater, punctuated small lava fountains 15 to 30 meters high. The lava cascades over a hundred meters towards the bottom of the crater, where it begins to form a lake.
Kilauea Iki / 1959 eruption - Explanatory panel of the eruption and formation of the Kilauea Iki lava lake.
Kilauea Iki / 1959 eruption - 3rd episode lava fountain above Crater rim Drive road; fragments of lava are propelled to 425 m in height. - USGS / HVO photo
During the first 24 hours, the activity decreases and on the evening of November 15, only one vent remains active on the western part of the crack; the lava fountain will increase in height up to 60 meters and its flow increases, the exit point being unique.
The depth of the lava lake gradually increases, reaching 60 meters on the 19th, and 82 meters on November 20th. The flow is enormous, and of the order of 380,000 m³ / hour.
The height of the fountain increases: 180 meters on 17, 350 meters on 19 November. The tephras ejected form a five-meter thick layer near the fountain, forming a large area south of Kilauea Iki called Devastation Area, and build a cinder cone, called Pu'u Pua'i, the "gushing hill".
Kilauea Iki / 1959 eruption - Lava fountain at the base of the Pu'u Pau'i cone, feeding the Kilauea Iki lava lake during the 8th episode, just before the lava lake is filled to its maximum . - USGS photo
On November 21, the level of the lava lake exceeds that of the vent, forcing the fountain to spring through a meter of lava, which is propelled to the sky.
But at 19:45, the same day, the fountain decreases from a height of 210 meters in a few seconds, leaving only a few gas bubbles. The first of the 17 episodes is over; the volume of the lava lake is 31 million cubic meters (= 68 million tons), and its depth reaches 98 meters. He then drains until his level reaches that of the vent.
Kilauea Iki / 1959 eruption - lava flows back into the vent after the end of the last fountaining episode - USGS / HVO photo
The following 16 episodes are in the mode described for the first, with smaller volumes and shorter durations. However, a record is reached on December 16th, with a lava fountain 580 meters high.
Between the different episodes of fountaining, the surface of the lava lake cools and a circular platform of solidified lava develops: it will measure 15-60 meters wide, and will dominate the level of the lake of about fifteen meters.
At the end of some episodes, the lava flows back into the vent, even though the fountain continues, and large patches of lava crust follow the same path, creating a whirlpool.
Kilauea Iki / 1959 eruption - Eruption of Kilauea Iki 1959 - Assessment of magma flows and lava drainages during the different episodes - Last vignette: at the end of the eruption, the magmatic reservoir shows a POSITIVE balance of 10 million of m³ of magma, following drainages. - Doc. USGS
Kilauea Iki / 1959 eruption - Diagram of the magma balance emitted (red line) during the eruption during different fountains (orange zones).
The eruption produced a total volume of 102 million m³ of lava. Analyzes based on the inflation and deflation measures of the volcano have shown that the lava, which flowed back into the vent, returned to the magma chamber partly, the other escaped to the east rift of the volcano.
The lava lake only completely solidified in the 1990s, more than 30 years after the eruption ended. It constitutes the bottom of the current crater of 3 km on 1.5 km, oriented east-west. Its surface is irregular, riddled with pressure ridges, and covered by rocky debris from earthquakes that shook the walls in 1975 and 1983. The Pu'u Pua'i cone dominates the crater walls of 1,118 meters.
Kilauea Iki Lava Lake - View of the Kīlauea Iki Trail from the bottom of the crater towards Pu'u Pua'i (on the left) - photo Navin Rajagopalan
Kilauea Iki Lava Lake - Solidified lava platform built during the cooling of the lava lake. - photo Hermann Luyken
Kilauea Iki Lava Lake - Circular pressure ridge at the surface of the lava lake of Kīlauea Iki - photo Diego Delso 2007