Structure of Volatile Conduits beneath Gorely Volcano (Kamchatka) Revealed by Local Earthquake Tomography

Geosciences

Evgeny I. Gordeev¹  Sergey Senyukov²  Sami El Khrepy³  Nassir Al Arifi³  Pavel Y. Kuznetsov⁴  Ivan Koulakov⁴  Andrey Jakovlev⁴  Ilyas Abkadyrov⁴  Evgeny Deev⁴ 

[1] Institute of Volcanology and Seismology FEB RAS, Piip Boulevard, 9, 693006 Petropavlovsk-Kamchatsky, Russia;Kamchatkan Branch of Geophysical Survey RAS Piip Boulevard, 9, 693006 Petropavlovsk-Kamchatsky, Russia;King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia;Trofimuk Institute of Petroleum Geology and Geophysics SB RAS, Prospekt Koptyuga, 3, 630090 Novosibirsk, Russia;

关键词: Gorely volcano;    travel-time tomography;    gas contamination;    magma reservoir;    degassing;   

DOI  :  10.3390/geosciences7040111

来源: DOAJ

【 摘 要 】

Gorely is an active volcano located 75 km from Petropavlovsk-Kamchatsky, Kamchatka. In 2010–2015, it exhibited strong activity expressed by anomalously high gas emission. In 2013–2014, we deployed a temporary network consisting of 20 temporary seismic stations that operated for one year. We selected 333 events with 1613 P-wave and 2421 S-wave arrival times to build the first tomographic model of this volcano. The seismic model was carefully verified using a series of synthetic tests. Our tomographic model provides a mechanism for volatile feeding of Gorely. An unexpected feature of the model was low Vp/Vs ratios; below 1.4 in some parts. One reason for such low Vp/Vs ratios is gas contamination due to magma degassing. In the central part of the model, directly underneath the Gorely crater, we observe a 2.5 km wide and 1.5 km thick seismic anomaly with a very high Vp/Vs ratio of up to 2. This may represent a magma reservoir with a high melt and/or volatile content. The upper limit of this anomaly, 2.5 km below the surface, may indicate the degassing level, which coincides with the most intense seismicity. Below this reservoir, we observe another columnar high Vp/Vs ratio anomaly. This can be interpreted as a conduit bringing magma and fluids from deeper sources.

【 授权许可】

Unknown