Seismogeodynamics in the Kaa-Khem Fault Zone (Southeastern Tuva) in 1905-2012

摘要

The two strong bursts of seismic activity in Tuva with the main events on December 27,2011 (M=6.7), and February 26, 2012 (M = 6.8), are examples of a unique and unexpected evolution of a seismic process. The main peculiarities of the 2011-2012 Tuva earthquakes are the following: These events occurred on a territory that was not noted for significant seismic activity (M ≥ 5.7) for several centuries. The seismic activation was represented by two events of nearly equal magnitude and almost at the same time, each with aftershock series. The seismic process in the form of mainshocks and aftershocks (including the events of M= 5.0-5.3) had a linear character (i.e., events were clustered within the same active structure) and were directed as well. This spatial linearity correlates with the seismogen-erating structure of the Kaa-Khem fault, on which only earthquakes of up to M = 5.3-5.7 had occurred during the 20th century, and in a certain sequence, at that.