Altay Seismicity Evolution after the 2003 Chuya Earthquake

Abstract

The 2003 Chuya earthquake had a noticeable impact on the seismicity of the whole Altay region. The article presents data on changes in the seismic regime of Altay from 2003 to 2021. It is shown that in the first six months after a major earthquake in 2003, earthquakes occur in the epicentral zone, and other structures of Altay are aseismic. After 2009, changes are formed both in the near zone, covering geological structures adjacent to the epicenter, such as the Aigulak, Kuray, South Chuya, North Chuya ridges, and in the far zone at distances of 250‒300 km from the epicenter and in different directions from it. After the Aigulak earthquake of 2019, an aftershock process was formed, which ensured the displacement of the center of Altay seismicity into the ridge of the same name. The explanation of the seismicity development in space and with time delays for years can be given on the basis of the influence of a large earthquake on the multi-layered lithosphere in accordance with models that assume the occurrence of disturbances during a large earthquake not only in the fragile part of the earth’s crust, but also in layers with high plasticity.