THE WAVE GEODYNAMIC IMPACT OF TECTONIC PROCESSES ON THE AMURIAN PLATE

The analysis of data on the migration of earthquakes and slow deformations from the Indo-Eurasian collision and the Western Pacific subduction zones is given, and the wave “geodynamic impact” of these tectonic processes on the Amurian plate and surrounding structures is shown. The interaction and a relative contribution of collision and subduction to the recent geodynamics of the Amurian plate are discussed. A scheme is constructed showing localizations of the slow strain wave manifestation in the areas of central and eastern Asia. The calculations are performed aimed at revealing a transverse migration of earthquakes (M ≥ 6.5) directed from the Japan and the Kuril-Kamchatka trenches toward the Asian continent during the time period from 1960 to 2015. The migration of earthquakes along the profile crossing Hokkaido Island occurs at velocities of 15 and 23 km/yr, whereas the migration velocity from the Kuril-Kamchatka Trench via Sakhalin Island is evaluated from 20 to 40 km/yr at different depths. We focus on an insufficient study of the influence of the Western Pacific subduction on the formation of the deformation field in continental Asia.

Geodynamics of Gorkha earthquake (Mw 7.9) and its aftershocks

A devastating earthquake (Mw 7.9) occurred in Gorkha region on 25 April 2015 caused loss of 8964 human lives and huge property in Central Nepal and adjoining region. Sequence of aftershocks, including four having magnitude greater than 6 occurred within 18 days, confined in a distance of about 150 km from Gorkha to Dolakha. Main shock and its aftershocks series confined in a depth range of 12 to 21 km. In this study, using 11 CMT solutions of earthquakes with magnitude 5 and above, occurred between 2014.12.18 and 2016.11.27 within 84o to 87o E and 27o to 29o N, we analyze faulting pattern of the Gorkha earthquake and associated large aftershocks to reveal recent geodynamics pattern in the central Himalayan region. Nodal planes of mainshock and four large aftershocks have east west orientation and shallow dip (6o to 23o) towards north, exhibit strong thrust mechanism. Smaller aftershocks scattered within 150 km long rupture zone along NW to SE direction show similar mechanism with large thrust component. Collective dips of nodal plane of ten events indicate northward under thrusting of the Indian plate at shallow angle, though the nodal plane of individual event differ slightly in their orientation. The cross-sectional study of focal mechanism shows the clustering of the seismic events at different depth with diverse faulting pattern. It is inferred that recent seismic activity in central Nepal region is dominated by thrust faulting and the mechanism which were responsible for the formation of Himalaya are still continuing.

Unified observation network for geodynamic monitoring in FEB RAS: formation, 10 years of development and major achievements

Обсуждается проблема современной геодинамики Дальневосточного региона на основе мониторинга разномасштабных деформаций и сейсмичности в области сочленения Евразийской, Североамериканской, Тихоокеанской, Амурской и Охотской литосферных плит с применением современных методов космической геодезии и широкополосной сейсмологии. Дан краткий обзор этапов развития Единой сети геодинамических наблюдений ДВО РАН, основных результатов сейсмологических и GPS/ГЛОНАСС-наблюдений, полученных в рамках целевой комплексной программы научных исследований ДВО РАН «Современная геодинамика, активные геоструктуры и природные опасности Дальнего Востока России (2009–2013 гг.)» и проектов ДВО РАН 2014, 2018, 2019 гг., а также достигнутых позиций ДВО РАН в области геодинамики. The problem of the recent geodynamics of the Far East region is discussed based on monitoring of different-scale deformations and seismicity in the articulation of Eurasian, North American, Pacific, Amurian and Okhotsk lithospheric plates using modern methods of space geodesy and broadband seismology. We present a brief overview of the development stages of the Unified Network of Geodynamic Observations of the Far Eastern Branch of the Russian Academy of Sciences, the main results of seismological and GPS/GLONASS observations obtained within the framework of the Targeted Comprehensive Research Program of the Far Eastern Branch of the Russian Academy of Sciences for 2009–2013 «Recent geodynamics, active geological structures and natural hazards of the Far East of Russia», Projects of the Far Eastern Branch of the Russian Academy of Sciences (2014, 2018, 2019) and the achievements of FEB RAS in the field of geodynamics.

Recent geological processes within the eastern part of the Belarusian Polesye area

Some features of recent geodynamics are presented. Special attention was given to those processes that cause evident deformations of the natural and antropogenic complexes, result in the damage to properties, and exert an adverse effect upon the health of the population. The spatial distribution of such processes is sketched, and some their quantitative characteristics are provided. It was concluded that the extremal features of recent geodynamics could be considered as the natural or natural-antropogenic dangers of the lithosphere class.