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Earth of fire

Actualité volcanique, Article de fond sur étude de volcan, tectonique, récits et photos de voyage

The east end of the east rift zone of Big Island was the scene of a famous eruptive flank sequence in 1960, which transformed a rural paradise in a nightmarish landscape.

After the summit eruption of Kilauea Iki Crater in late 1959 , the seismicity increased on 13 January 1960 along the Kapoho fault. This fault borders the Kapoho graben to the south-east, while the fault Koa'e limit the north-west side ( Map 1 ) .

In the afternoon of 13 January, the graben has fallen by more than a meter, fault Kapoho side , and by one meter twenty Koa'e fault side . Population to evacuate spontaneously ... and on 7:35 p.m., the sky turned red heralds the beginning of the eruption.

A long segmented fissure, 900 meters, lets out lava fountains during half an hour, forming a curtain of fire from a height up to 100 meters . Then, during several hours , the activity decreases to the either side of the crack to increase in its central part . Lava a'a flows spread to the NE, accompanied by explosions of methane and blue flames . To 23:15, steam explosions mark the vent H , following the likely meeting between water (brackish or seawater) and lava .

1960 January 14 - Kapoho eruption - by D.H. Richter.
Kilauea - East Rift Zone - violent steam emission by two adjacent vents, and fountaining at two separate vents - 14/01/1960 Photo DHRichter / USGS - HVO

Earlier January 14, steam explosions cease, and fountaining is confined to a section of 200 m. between B and E vents. The fallouts building a rampart spatter/slag of ten meters height, open NE side, from where an a'a stream flows down the graben over 1500 m.

kapoho 1960.01.14 - HVO
Hawaii - East Rift Zone - 01/14/1960 map with Kapoho and Koa'e faults, delimiting the graben Kapoho - vents A to J were active the first two days of eruption . - USGS - HVO map

January 15 , the a'a lava flow reached 6m. thick and 300 m. wide where it crosses the road Koa'e - Pohoiki . It reaches the sea on 8h, by generating a vapor curtain in advancing . Casting pours southward towards Higashi Pond, formed during a collapse after the seismic crisis of 1924. The lava will continue to invade until it is completely filled on January 20 .


1960.01.15 - Fountain and cone at vent B as seen from Pu`u
Hawaii - the Kapoho eruption 01/15/1960 - fountaining and cone vent B, with a cast a'a flowing to the right of the cone - Kapoho few houses are visible on the left, in the foreground - photo JP Eaton / USGS - HVO

Meanwhile, on January 18 , lava fountains of vent B reach a height of 365-425 m., expelling incandescent pumice  to 900 m. height. The
fountains flow feeds a'a lava flows that move away from the cinder cone , and eventually overflow the wall of the graben toward Kapoho .

kapoho 1960.01.16 HVOkapoho 1906.01.19 - HVOEruption Kapoho - left, on 16.01 - right, on 19/01/1960
-  HVO maps 
( click on the maps for a larger view )

kapoho 1960.01.23 - HVO
       Kapoho Eruption on 01/23/1960 - note the lava barriers, hatched in blue - USGS - HVO map

Three brave attempts were made to stop the flows threatening Kapoho  and subdivisions, from January 19 ( map above ) . In vain , since January 28, the cast reaches the third barrier and thickens to the dam to reach a height of 15 meters. Pressure injected lava in the cinder cone, Pu ` u ` i Kuki, uncompacted, ... dislocated this one and plunges beneath the dam to come out to the south, and bury the village's school . The barrier resist  until February 5, when it is completely covered by lava that encircles the Pu'u Kukae .

Another barrier, 1.6 km long, is built on January 21 between Pu`u Kukae and the ocean, to prevent the penetration of the lava to Kapoho Beach Lots and coastguard facilities in Cape Kumukahi . It will contain a time the flows, but yields in four places on 28 in the afternoon, before being covered 29 .

1960.01.23 - JP Eaton (2)
         Eruption Kapoho 23/01/1960 - cone vent B, with a'a lava flow - photo JPEaton / USGS - HVO

The fate of Kapoho is sealed on 27.01 : a very fluid lava comes out of the vents B , L and K , fueling a'a flows between Pu`u`Kuki'i and Kapoho . This new source condemns the city ... at 23:30 , the lava flows reached the city , and in 30 minutes,  a'a flows moves to SO in the streets, covering house after house . On 27 midnight, most of Kapoho is destroyed .

1960.01.31 - by J.P. Eaton  
Eruption Kapoho - Fountain of 200-300 m high above the vent B - photo JPEaton / USGS - HVO

 

On the night of January 30 to 31 , the measured temperature of lava fountains increased significantly in relation to a change in mineralogy (the content of lava in olivine , low to absent, changes and olivine becomes the dominant phenocryst) ... later we will discover that a quantity of hotter magma from the summit area of ​​Kilauea is mixed with cooler magma stored in a reserve under the Kapoho area, since 1955 or before .

Kapoho map after 1960 eruption
Kapoho post-eruption map - lava flowing extension of the shore- line -  On February 4, 1960 , the lava completely surrounds the double cone
Pu`u Kukae-Pu`u Kuki`i.. - Doc . USGS - HVO

At the end of the eruption, the lava has covered over 10 km², including 2 km² of new land formed beyond the original line of coast. The volume of lava emitted is estimated at 122 million cubic meters , plus 7.5 million cubic meters of pyroclastic material .

To follow: the implications of the Kapoho eruption at the summit of Kilauea.

Source: HVO - Hawaiian Volcano Observatory

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