Localization of the Source of a Strong Historical Earthquake in Central Tuva Using Folklore-Historical and Paleoseismological Data

Abstract

The article presents the results of studies of the source of a strong earthquake in Central Tuva. The studies were carried out using both the widespread geological and geomorphological approach of paleo-seismological orientation, and the methods of historical seismology. Primary information about the source and its location was found in folklore sources with a toponymic reference, using which traces of the earthquake were found and mapped on the field. Traces of earthquakes are confirmed by seismic ruptures in the zone of the Ulugkhem active fault and secondary evidences. Preliminary dating of the event is 1715‒1758, magnitude Mw = 6.5‒7.0. The intensity of the earthquake at the epicenter reached VIII–IX (ESI-2007 scale). In the zone of the Ulugkhem active fault, the consequences of the catastrophic explosion of 1950, which led to human casualties and destruction, were mapped. The results of the research make it possible to clearly define the northern boundary of the Kyzyl intermountain basin as a fault with reverse-sinistral kinematics of displacements in the Holocene, and identification of the epicentral zone of a historical earthquake is necessary to assess the seismic hazard of the most densely populated region of Tyva Republic.