Actualité volcanique, Articles de fond sur étude de volcan, tectonique, récits et photos de voyage
Par Bernard Duyck
The northeast shore of Lake Kuril is dominated by the conical silhouette of the Ilyinsky volcano, nestled in a small depression.
A first volcano was formed to 5,700 BC, on the edge of the NE rim of Lake Kuril caldera.
The modern building was built in a large caldera of 4 km., produced by the collapse of the proto- volcano. Pyroclastic deposits of Ilyinsky overcome the ignimbrite emitted during the eruption of Lake Kuril , showing by their composition that the beginning of the eruption of Ilyinsky follow that which caused the collapse of the caldera Kuril , and a genetic correlation .
After a rest of 1700 years , a major explosive eruption of VEI 5 took place in 2850 BC. Other eruptions are reported in 2050 BC and 50 AD , producing thick andesitic lava flows , and before a new long rest.
Ilyinsky and thick andesitic flows of more than 200 m. formed in the year 50 - photo Sulerzhitsky LD / KSCNET
In 1901, a phreatic eruption formed a maar crater on the eastern flank of the volcano. It is wide of 800 to 1,000 meters , 200 meters deep and breached by a canyon northeast side.
In the foreground, the inner wall of the flank maar of Ilyinski (1901) and Zheltovsky volcano in the background - photo Sulerzhitsky LD / KSCNET
In contrast to the Ilyinsky, the Zheltovsky is a composite building : a large volcanic pedestal is topped by a caldera dated to late Pleistocene . The latter contains a stratovolcano, dated to the late Pleistocene , wearing several extrusive domes formed during the Holocene . The extrusion of domes is related to debris on the slopes of the volcano.
In addition, various explosive eruptions occurred : one , there is 3-4000 years , emitting basalto - andesitic ash ; another around the year 1500 , producing andesitic blocks and ash ; the last in the 19th. century , with fallout of rounded basaltic lapilli rich in inclusions of allivalite and eucrite . Recent eruptions have caused significant lahars , which have reached the Pacific coast.
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