DETECTION OF FEATURES OF THE STRONG EARTHQUAKE OF MARCH 25, 2020

TO THE EAST OF THE KURIL ISLANDS BASED ON THE SEISMIC ENTROPY METHOD

S.Ts. Akopian

Schmidt Institute of Physics of the Earth, Russian Academy of Sciences, Moscow, Russia

e-mail: akopian@ifz.ru

Abstract. Using the seismic entropy method, the nucleation of the recent earthquake of March 25, 2020 (M = 7.5) to the east of the Kuril Islands is studied. This earthquake, by analogy with the doublet of the strong earthquakes of 2006–2007 in the Central Kuril Islands, revealed the frontal system in the Northern Kuril – Kamchatka region. The frontal seismic systems are located in the central segments of the Kuril-Kamchatka arc and are separated from the rear systems by an oceanic trench. These seismic systems allow us to describe the preparation of unusually strong rare earthquakes in the Pacific plate before the subduction zone, to reveal the dynamics of slow stress accumulation over decades, to schematically simulate the deformations of interacting plates before strong earthquakes, and to conduct a comparative analysis of these deformations in the central and northern Kurils. Frontal and rear seismic systems in the Northern Kuril – Kamchatka region with threshold magnitudes 8.4, 7.8, 7.4 and 6.6 are described in detail. It is shown that in the mega-seismic system with a threshold magnitude of 8.4, a large entropy is accumulated and a mega-earthquake with magnitude M ≥ 8.7 is being prepared. A comparative analysis with the trajectory of the preparation of catastrophic Kamchatka earthquake of 1952 shows that it can happen to 2029. Monitoring of seismicity based on the identified hierarchy of rear and front systems will improve the quality of forecasts and reveal the role of very rare strong earthquakes in the interaction of plate segments in the subduction zone.

Keywords: seismic system, track diagram, seismic entropy, seismicity monitoring, Kuril–Kamchatka arc

About the author

AKOPIAN Samvel Tsolakovich – Doctor of Physical and Mathematical Sciences, Chief Researcher, Schmidt Institute of Physics of the Earth of the Russian Academy of Sciences. 123242, Moscow, ul. Bolshaya Gruzinskaya, 10, building 1. E-mail: akopian@ifz.ru

Cite this article as: Akopian S.Ts. Detection of features of the strong earthquake of March 25, 2020 to the east of the Kuril Islands based on the seismic entropy method, Voprosy Inzhenernoi Seismologii (Problems of Engineering Seismology). 2020. V. 47, No. 2. P. 5–18. [in Russian]. https://doi.org/10.21455/VIS2020.2-1

English translation of the article will be published in Seismic Instruments, ISSN: 0747-9239 (Print) 1934-7871 (Online), https://link.springer.com/journal/11990