Recognition of earthquake-prone areas in the Altai-Sayan-Baikal region

The goal of the study is to identify the possible locations of strong M6+ earthquakes in the Altai-Sayan-Baikal region.

The first stage of the study is compiling the morphostructural map of the region by means of the morphostructural zoning method (MSZ). The map presents the hierarchical block structure of the region, the network of morphostructural lineaments bounding the blocks, and loci of the nodes forming around lineament intersections. Epicenters of M6+ earthquakes reported by earthquake catalogues nucleate at nodes. We apply the pattern recognition approach to identify among all nodes seismogenic nodes D capable of generating M6+ earthquakes. This is done based on the description of the nodes by a set of geological and geophysical characteristics measured uniformly for all nodes. The result of the pattern recognition is twofold: (i) the rule of recognition that allows to recognize D nodes among the whole set of nodes; (ii) the actual division of nodes according to this rule into separate two classes: seismogenic D nodes and N nodes where  the target events are unlikely. In the region under consideration, the whole set of 97 nodes has been divided into 33 D nodes and 64 N nodes. The target earthquakes have not yet been recorded at 17 D nodes indentified in this work. These susceptible nodes are located on the high rank lineaments separating major morphostructures of the region. High seismic potential of some of such nodes is confirmed by paleoseismic features defined in the region by other researchers.

Morphostructural map of the Altai-Sayan-Baikal region and seismogenic nodes recognized in the region. Continuous lines mark the longitudinal lineaments, dashed lines depict the transverse lineaments. Bold lines show the lineaments of the 1st rank, middle lines mark the lineaments of the 2nd rank, hairlines depict the lineaments of the 3rd rank. Red dots depict epicentres of earthquakes with M ≥ 6. Circles depict nodes capable of earthquakes with M ≥ 6.

Source: Gorshkov,A.I., and A.A.Soloviev, Recognition of earthquake-prone areas in the Altai-Sayan-Baikal region based on the morphostructural zoning. Russ. J. Earth Sci., 2021, 21: ES1005, doi:10.2205/2020ES000751.