Environmental effects of the 2011--2012 Tuva earthquakes (Russia): application of ESI 2007 macroseismic scale in the Siberian mountains

Abstract

The data on the environmental manifestation of the Tuva earthquakes 27.12.2011 ($Ms=6.7$) and 26.02.2012 ($Ms=6.8$) are presented. The earthquake effects are distinctly divided into two groups: the secondary effects as result of the seismic shaking and primary effects which are directly related to the seismic rupture at the surface. The small length of the seismic ruptures of both earthquakes comparing to the magnitude is their distinctive feature. The data on the distribution of the total secondary effects of both earthquakes are collected. The shock intensity map (ESI~2007 scale) is compiled. For the case of the Tuva earthquakes ESI~2007 scale proves to be of an indispensable tool because of the other criteria lack for the assessment of the shock effects within the epicentral area. The use of the ESI~2007 scale revealed some difficulties in its application for the Siberian mountain: the scale did not consider the difference between permafrost and not permafrost soils, as well as between winter and summer conditions. Obviously the earthquake manifestations widely vary depending on these conditions in Siberian continental climate. Nevertheless the use of scale allowed us to obtain a large amount of new data on the effects of strong seismic events in the Altai--Sayan region.