An earthquake which struck in south-western Siberia on February 26, 2012 was unusual for an event of its magnitude (early indications are that it was around 6.7 magnitude) in that it occurred in an area of relative tectonic stability. A glance at the US Geological Survey (USGS) earthquake map of the region since 1990 shows little in the way of historic seismic activity compared to other regions of the earth where tremors are regular and significant.
The earthquake struck near the Mongolian border, some 60 miles east of the Russian city of Kyzyl and over 2300 miles from the country’s capital, Moscow. It was followed by a series of aftershocks of up to M5.2. Previous seismic events of a similar size have been recorded in the area, with an event of M6.3 in December 1991, and one of M7.3 in September 2003.
Tectonic Summary: Southwest Siberia
Although maps of the area immediately surrounding the epicentre show no plate boundaries, this earthquake, and the others preceding it, are nonetheless generated by the movement of the earth’s tectonic plates. Most earthquakes are associated with either conservative boundaries (where the plates move laterally past one another) or with destructive boundaries, where one plate is subducted (forced below another). In these cases, earthquakes are generated along a relatively narrow belt of the earth’s surface.
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