Shiveluch volcano: seismicity, deep structure and forecasting eruptions (kamchatka)
ABSTRACT The deep structure, Wadati-Benioff zone (focal zone) geometry and the magma feeding system of Shiveluch volcano are investigated based on 1962–1994 detailed seismic surveillance.A focal zone beneath Shiveluch is dipping at an angle of 70° at depths of 100–200 km. Based on the revealed interrelations between seismicity at depths of 105–120 km and an extrusive phase of its eruptions in 1980 through 1994, it is inferred that primary magmas, periodically feeding the crustal chamber, are melted at depths of at least 100 km. An upsurge of extrusive-explosive activity at the volcano is preceded and accompanied by the increasing number and energy of both volcanic earthquakes beneath the dome and tectonic or volcano-tectonic earthquakes in the zones of NW-striking crustal faults near the volcano.The eruption of April 1993 has been the most powerful since 1964. It was successfully predicted based on interactive use of all seismic data. At the same time the influence of seismicity at depths of 105–120 km under the volcano on the style (and consequently on prediction) of its activity is decisive.
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ABSTRACT: On November 12, 1964, after a long swarm of preliminary earthquakes a gigantic directed blast took place at Shiveluch Volcano. The Crater top of the volcano with five large domes was completely destroyed. The deposits of the directed blast fell on an area of 98 sq. km, at a distance up to 10 km from the crater. The volume of the deposits is 1.5 km3 at least. A new crater was formed, its size is 1.5 × 3 km. Numerous pyroclastic flows were poured out the new crater. The eruption lasted only one hour, its thermal energy is 1,3 × 1025 ergs, kinetic energy of the blast − 1 × 1024 ergs, air wave energy − 1,8 × 1021 ergs. Initial velocity of the explosion: 280–310m/sec, pressure: 800–1000atm. The eruption of Shiveluch volcano belongs to the « Bezymianny type » eruption.Bulletin of Volcanology 02/1970; 34(1):261-288. · 2.65 Impact Factor