ON THE RELEVANCE AND POSSIBILITY OF PREVENTING SEISMIC HAZARDS IN THE TIEN SHAN

Abstract

The problem of activation of the seismic regime of the Tien Shan and the possibility of strong earthquakes in its southern and northern foothills in the next few years in connection with the earthquake of January 23, 2024, which occurred in the southern foothills of the Central Tien Shan in Ushi County (Ukturpan) of Aksu Prefecture of Xinjiang Province of the People's Republic of China, an earthquake of magnitude 7.1 occurred near the city of Aksu. The Ushinsky earthquake of 23.01.2024 may mean the beginning of a new seismic activation of the Tien Shan. Here is the previous cycle of eight strongest earthquakes with M=6.9-8.3 in the northern and six with M=6.8-7.8 in the southern foothills of the Tien Shan, which lasted 100 years, began in 1885 with the Belovodsky earthquake (M=6.9 near Bishkek) and ended with the Kashgar earthquake (M = 7.0) in 1985. There was another strong Suusamyr earthquake with M = 7.3 in 1992 in the middle part of the Tien Shan, which is atypical in this region. With the earthquake of Usha, the period of calm for earthquakes with magnitudes 7.0 and more, which lasted for almost 40 years, ended.

A brief overview of the current state of the issue of forecasting strong earthquakes is given. It is noted that there is a certain discrepancy between the basic concepts of the existing earthquake source models and the available geomechanical data on the fragile destruction of rocks.

The latest achievements of tectonophysics in the field of studying the current stress state directly in rock massifs are presented. It is shown that, based on the results of tectonophysical reconstruction of natural stresses, it is possible to perform zoning of active faults according to the level of coulomb stresses responsible for the implementation of brittle fracture. The analysis of the results of active fault zoning performed in the foci of the strong Wenchuan earthquake (M=8.0, 2008) and the Karamushir earthquake (M=7.8, 2023) is given.

The analysis of the possibilities for long-term and short-term forecasting based on a complex of seismic, seismotectonic and geophysical methods based on the results of tectonophysical zoning of active faults is performed.