Geophysical research: article

R.A. Reznichenko 1 A.G. Goev 1,2 I.M. Aleshin 2 S.A. Tarasov 1 L.I. Gontovaya 3 D.V. Chebrov 4
1 Sadovsky Institute of Geosphere Dynamics of the Russian Academy of Sciences 2 Schmidt Institute of Physics of the Earth, Russian Academy of Sciences 3 Institute of Volcanology and Seismology Far Eastern Branch of the Russian Academy of Sciences 4 Kamchatka Branch of Geophysical Survey, Russian Academy of Sciences
Journal: Geophysical research
Tome: 24
Number: 2
Year: 2023
Pages: 25-38
UDK: 550.437
DOI: 10.21455/gr2023.2-2
Full text
Keywords: seismology, receiver function, deep structure, velocity models, Kamchatka peninsula.
Аnnotation: The article is devoted to the study of the structure of the Earth's crust and upper mantle of the Avachinskaya Bay region of the Kamchatka Peninsula. One-dimensional sections of the dependence of seismic velocities on depth, obtained during the study are presented. These sections are built according to the data of “Petropavlovsk” (PET), “Dalniy” (DAL), “Institut” (IVS) and “Karymshina” (KRM) stations for the period from 2000 to 2019. The stations are part of the permanent observational network of seismic stations of the Kamchatka Branch of the Unified Geophysical Service of the Russian Academy of Sciences. The sections are built to a depth of 300 km, which makes it possible to characterize the structure of the medium in the bay area, namely, to identify structural layers in the Earth's crust, the Mohorovichich boundary, and to estimate the degree of deviation of seismic wave velocities in the upper mantle from the corresponding values of the IASP91 global Earth model. The average values of velocities calculated from the obtained sections in the Earth's crust and upper mantle turned out to be noticeably lower compared to the global model. The average deviation of the observed velocities from the model ones is 0.5–1.0 km/s in the crust, and then gradually decreases down to a depth of about 180 km. At greater depths, the velocities in the obtained models coincide with the standard values. It should be noted that at the locations of the seismic stations, the lower boundary of the subducting Pacific Plate runs at depths of about 180 km. Therefore, the main reason for the difference in velocities is probably related to the significant heating of the matter and the complex fluid-dynamic situation in the region of the mantle wedge.
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