gtcrustГеодинамика и тектонофизикаGeodynamics & Tectonophysics2078-502XInstitute of the Earth's crust of the Russian Academy of Sciences, Siberian Branch10.5800/GT-2022-13-3-0641gtcrust-1534Research ArticleСОВРЕМЕННАЯ ГЕОДИНАМИКАRECENT GEODYNAMICSПАРАМУШИРСКОЕ ЗЕМЛЕТРЯСЕНИЕ 25.03.2020 г., М W =7.5, И ЕГО ВЛИЯНИЕ НА СОВРЕМЕННУЮ ГЕОДИНАМИКУ ПРИЛЕГАЮЩЕГО УЧАСТКА КУРИЛО-КАМЧАТСКОЙ ЗОНЫ СУБДУКЦИИTHE MARCH 25, 2020 MW=7.5 PARAMUSHIR EARTHQUAKE AND ITS IMPACT ON RECENT GEODYNAMICS OF THE ADJACENT SECTION OF THE KURIL-KAMCHATKA SUBDUCTION ZONEПрытковА. С.PrytkovA. S.

 693022, Южно-Сахалинск, ул. Науки, 1Б, Россия 

1B Nauki St, Yuzhno-Sakhalinsk 693022, Russia

a.prytkov@imgg.ruВасиленкоН. Ф.VasilenkoN. F.

 693022, Южно-Сахалинск, ул. Науки, 1Б, Россия 

1B Nauki St, Yuzhno-Sakhalinsk 693022, Russia

Институт морской геологии и геофизики ДВО РАНРоссияInstitute of Marine Geology and Geophysics, Far Eastern Branch of the Russian Academy of SciencesRussian Federation202220092022133641641Copyright © Прытков А.С., Василенко Н.Ф., 20222022Прытков А.С., Василенко Н.Ф.Prytkov A.S., Vasilenko N.F.Данная работа распространяется под лицензией Creative Commons Attribution 4.0.This work is licensed under a Creative Commons Attribution 4.0 License.https://www.gt-crust.ru/jour/article/view/1534

25 марта 2020 г. юго-восточнее о. Парамушир (Северные Курильские острова) под внешним тихоокеанским склоном Курило-Камчатского глубоководного желоба произошло внутриплитовое цунамигенное землетрясение с магнитудой МW=7.5. Землетрясение оказалось сильнейшим с 1900 г. сейсмическим событием для прилегающих к эпицентру океанического склона протяженностью около 800 км и трехсоткилометрового сегмента Курильской сейсмофокальной зоны. В очаге землетрясения реализовались напряжения субгоризонтального сжатия, ориентированные вкрест сейсмофокальной зоны. Тип подвижки – взброс по обеим нодальным плоскостям.

Напряженное состояние сжатия, в условиях которого произошло Парамуширское землетрясение, отражает современную геодинамическую обстановку в прилегающей к гипоцентру зоне субдукции. В работе показано, что возникновение землетрясения обусловлено высокой степенью сцепления поверхности механического контакта Тихоокеанской и Североамериканской литосферных плит в зоне субдукции. На основе анализа косейсмического смещения ближайшей Global Navigation Satellite System (GNSS) станции подтвержден выбор действующей плоскости сейсморазрыва в очаге землетрясения. Сейсмогенерирующая подвижка произошла по плоскости, ориентированной в юго-западном направлении и падающей в сторону глубоководного желоба. Для дислокационных моделей очага Finite fault рассчитаны приращения кулоновского напряжения в зоне субдукции. Для приоритетной плоскости сейсморазрыва приращение кулоновского напряжения в области межплитового контакта распространяется до глубины ~30 км и достигает 1 бара.

Косейсмическое приращение напряжений в зоне субдукции на северном фланге Курильской островной дуги, который на современном этапе тектонического цикла обладает высоким нереализованным сейсмическим потенциалом, в долгосрочной перспективе повышает вероятность возникновения здесь сильнейшего межплитового землетрясения.

An intraplate tsunamigenic earthquake with МW=7.5 occurred on March 25, 2020 southeast of the Paramushir Island (Kuril Islands) beneath the outer slope of the Kuril-Kamchatka Trench. Since 1900, this earthquake has been the largest event for an 800-km long oceanic slope and a 300-km long segment of the Kuril seismofocal zone located near the epicenter. Sub-horizontal compression stresses generated in the earthquake source region were oriented across the seismofocal zone. A type of motion is represented by reverse faulting along the both nodal planes.

The compressive stress state in which there occurred the Paramushir earthquake reflects the present-day geodynamics in the subduction zone near the hypocenter. The paper shows that the earthquake occurrence is due to a strong mechanical contact surface between the Pacific and North American lithospheric plates in the subduction zone. The analysis of coseismic displacement of the nearest Global Navigation Satellite System (GNSS) station served as confirmation of the determination of fault plane solution of the earthquake. A seismogenerating motion occurred along the plane oriented to the southwest and dipping towards the trench. For Finite fault source models, there were calculated the increments of the Coulomb stress in the subduction zone. For the main fault plane, the increment of the Coulomb stress in the interpolate contact area propagates to a depth of ~30 km and reaches 1 bar.

Coseismic stress increment in the subduction zone at the northern flank of the Kuril island arc, which has a high seismic potential at the present stage of the tectonic cycle, increases the likelihood of the largest interplate earthquake occurrence therein.

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The authors declare that there are no conflicts of interest present.