TY - JOUR

T1 - Tomographic Images of Magma Chambers Beneath the Avacha and Koryaksky Volcanoes in Kamchatka

AU - Bushenkova, Natalia

AU - Koulakov, Ivan

AU - Senyukov, Sergey

AU - Gordeev, Evgeny I.

AU - Huang, Hsin Hua

AU - El Khrepy, Sami

AU - Al Arifi, Nassir

N1 - Publisher Copyright: ©2019. American Geophysical Union. All Rights Reserved.

PY - 2019/9/1

Y1 - 2019/9/1

N2 - 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.

AB - 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.

KW - Avacha volcano

KW - Kamchatka

KW - Koryaksky volcano

KW - magma reservoirs

KW - seismic tomography

KW - COLOMBIA

KW - SEISMICITY

KW - ALGORITHM

KW - BEZYMIANNY

KW - LOCAL EARTHQUAKE TOMOGRAPHY

KW - ACTIVE VOLCANOS

UR - http://www.scopus.com/inward/record.url?scp=85072193764&partnerID=8YFLogxK

U2 - 10.1029/2019JB017952

DO - 10.1029/2019JB017952

M3 - Article

AN - SCOPUS:85072193764

VL - 124

SP - 9694

EP - 9713

JO - Journal of Geophysical Research: Solid Earth

JF - Journal of Geophysical Research: Solid Earth

SN - 2169-9313

IS - 9

ER -