Inyo Craters volcanCratères d'Inyo sont un champ long de 12 km de dômes de lave à la bordure orientale de la Sierra Nevada, en Californie, près de la ville de mammouth et au sud du champ des cratères de Mono similaire. Le champ contient siliceuse 6 dômes de lave, coulées de lave et 15 cratères d'explosion (maars) qui la dernière éruption remonte à il y a environ 600 ans.
Introduction:The Inyo Craters overly the NW rim and parts of the floor of the older Long Valley caldera, but belong to a different volcanic system - they were fed by a different magma chamber.
Explosion craters of Mammoth Mountain volcano to the south are believed to belong to the Inyo Craters as well. Wilson Butte erupted about 1350-1200 years ago and produced pyroclastic flows which extended 9 km and covered 60 km2.
The latest eruptions at Inyo Craters about about 600 years ago were explosive eruptions that formed the prominent South Deadman, Obsidian Flow, and Glass Creek rhyolitic lava domes and lava flows. The Inyo Crater Lakes are small phreatic craters that formed during this eruption on the south flank of the older Deer Mountain rhyolite dome of the Long Valley caldera.
Source: GVP, Inyo Craters information
The Inyo Craters eruption about 600 years ago, Long Valley caldera, California
The last activity of the Inyo Crater occured at South Deadman, Obsidian Flow, and Glass Creek vents, producing spectacular explosion craters, deposits of pyroclastic flows and ashfall.
Ash fall from the initial phreatic and phzreatomagmatic phase at South Deadman vents is found more than 20 km NE and covered an area of 80 km2. The second phase from the Obsidian Flow vent saw the formation of a lava dome reaching a volume of 170,000 m3. A stong explosive eruption also ejected pumice and ash high into the air. The deposit is found more than 25 km to the NE and covers 140 km2.
The largest and final magmatic explosive activity of the Inyo eruptions occurred at the Glass Creek vent, located between Obsidian and South Deadman vents. Wind carried tephra from the eruption column toward the south-southwest. Near the vent, the resulting deposit is more than 8 m thick. At a distance of 12 km from the vent, the deposit is more than 50 cm thick. It covers ca. 9000 km2 and is found up to 190 km away.
Phreatic eruptions occurred again at the end of the eruption. 3 explosions south of Deadman flow formed Inyo Craters.
Source: USGS ...plus
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