Tomographic Images of Magma Chambers Beneath the Avacha and Koryaksky Volcanoes in Kamchatka

Natalia Bushenkova, Ivan Koulakov, Sergey Senyukov, Evgeny I. Gordeev, Hsin Hua Huang, Sami El Khrepy, Nassir Al Arifi

Результат исследования: Научные публикации в периодических изданияхстатья

2 Цитирования (Scopus)

Аннотация

A new tomographic model (Vp, Vs, and Vp/Vs ratio) was built for two neighboring active volcanoes, Avacha and Koryaksky, which represent a serious hazard to the population and infrastructure of Petropavlovsk-Kamchatsky, the main city of Kamchatka, Russia. Arrival times of seismic P and S waves from almost 5,000 local events, recorded by a permanent network of seismic stations during 2009–2018, were used for tomography. The resolution of the derived models was carefully tested by a series of synthetic simulations. Prominent anomalies with extremely high Vp/Vs ratios (up to 2.4) were retrieved directly beneath both volcanoes and interpreted as magma reservoirs containing high degrees of partial melt and/or fluids. Beneath Avacha, the upper limit of the anomaly is located at the depth of ~2 km below the surface. The reservoir appears to be connected to the surface by a neck-shaped anomaly of high Vp/Vs ratio associated with active seismicity, which is interpreted as a magma and fluid conduit. Beneath Koryaksky, the magma related anomaly is deeper: Its upper limit is located at a depth of ~7 km below the surface. This anomaly is connected with the volcanic cone and is associated with a vertical seismicity cluster, which possibly marks the pathway of fluid ascent and degassing. Between the volcanoes, a 2- to 3-km thick layer of very low Vp and Vs is interpreted as deposits of volcanoclastic sediments. Generally low Vp/Vs ratios in the area between the volcanoes show that the magma reservoirs in the upper crust are not interconnected.

Язык оригиналаанглийский
Страницы (с-по)9694-9713
Число страниц20
ЖурналJournal of Geophysical Research: Solid Earth
Том124
Номер выпуска9
DOI
СостояниеОпубликовано - 1 сен 2019

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