Seismicity and Seismic Hazard Assessment for the Magadan region on a Scale Close to Detailed Seismic Zoning

Abstract

This paper presents the results of a seismic hazard assessment for the Magadan region (quadrangle 58.5°–66.0° N, 143.3°–157.7° E) in terms of macroseismic scale units. The extent of the research corresponds to the regional one (in the terminology framework accepted in Russia, this corresponds to the scale of the detailed seismic zoning (DSZ)). The seismic activity matrix (A3.3) is obtained and the following main seismicity parameters are estimated: the slope of the recurrence graph, the average thickness of the seismoactive layer, and depth of this layer (h); on the basis of the obtained results, when constructing seismic intensity maps, the focal depth we used was h = 10 km. Proceeding from the analysis of comprehensive seismological, tectonic, and geological data, 13 zones of possible earthquake sources (PES zones) with Mmax = 6.5, 7.0 and 7.5 were distinguished in the Magadan region . Beyond the identified zones, the background seismicity was assumed to be Mmax = 5.0. The study resulted in obtaining probabilistic seismic hazard maps of the Magadan region in terms of macroseismic scale intensity units, calculated for average recurrence periods of 500, 1000, and 5000 years.