EGU2020-4539
https://doi.org/10.5194/egusphere-egu2020-4539
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Tomographic images of Avacha and Koryaksky volcanoes in Kamchatka

Natalia Bushenkova1,2, Ivan Koulakov1,2, Sergey Senyukov3, Evgeny I. Gordeev4, Hsin-Hua Huang5, Sami El Khrepy6,7, and Nassir Al Arifi6
Natalia Bushenkova et al.
  • 1IPGG SB RAS, Geophysics, Novosibirsk, Russian Federation (bushenkovana@ipgg.sbras.ru, koulakoviy@ipgg.sbras.ru)
  • 2Novosibirsk State University, Novosibirsk, Russian Federation
  • 3Kamchatkan Branch of Geophysical Survey RAS, Petropavlovsk-Kamchatsky, Russian Federation (ssl@emsd.ru)
  • 4Institute of Volcanology and Seismology, FEB RAS, Petropavlovsk-Kamchatsky, Russian Federation (gordeev@kscnet.ru)
  • 5Institute of Earth Sciences, Academia Sinica, Taipei, Taiwan (hhhuang@earth.sinica.edu.tw)
  • 6King Saud University, Riyadh, Saudi Arabia (k_sami11@yahoo.com, nalarifi@ksu.edu.sa)
  • 7National Research Institute of Astronomy and Geophysics, NRIAG, Helwan, Egypt

In this study, we have mapped for the first time robustly the 3D structure of two upper-crustal magmatic reservoirs beneath the active volcanoes Avacha and Koryaksky, which are called “home volcanoes” for Petropavlovsk-Kamchatsky, the main city of Kamchatka (~200,000 inhabitants). These volcanoes represent a serious potential hazard for the city, because they are located at a distance of 25–30 km from the populated areas. A new tomographic model (VP, VS, VP/VS ratio) was built, for which we used the 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.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 coneby a vertical seismicity cluster, which possibly marks the pathway of fluid ascent and degassing. Between the volcanoes, a 2–3 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.

This study was partially supported by the RFBR project # 18-55-52003.

How to cite: Bushenkova, N., Koulakov, I., Senyukov, S., Gordeev, E. I., Huang, H.-H., El Khrepy, S., and Al Arifi, N.: Tomographic images of Avacha and Koryaksky volcanoes in Kamchatka, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4539, https://doi.org/10.5194/egusphere-egu2020-4539, 2020

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Presentation version 2 – uploaded on 05 May 2020
Version description: At the request of Alina Shevchenko, the 4th slide with her result was deleted, although there was a link to her work on it[...]
  • CC1: Comment on EGU2020-4539, Thomas R. Walter, 05 May 2020

    thank you for updating  this presentation. Very interesting work!

    • AC1: Reply to CC1, Natalia Bushenkova, 05 May 2020

      Thank you for your interest in our work!

Presentation version 1 – uploaded on 26 Apr 2020 , no comments