Problems of Engineering Seismology: article

Аnnotation: Active faults in southern Transbaikalia, some of which are elements of the Mongol-Okhotsk lineament, are still poorly studied in seismic terms. The Chikoi fault has been characterized by weak earthquakes over a hundred-year period of instrumental observations, which does not give a knowledge of the seismic potential of the fault. But the distinct manifestation of the fault scarp in the modern relief suggests high rates of tectonic movements along it. This is also confirmed by the seismotectonic deformations discovered during our field studies. The field route work carried out in the zone of the Chikoi fault revealed signs of a seismogenic feature of the fault in segments with a total length of at least 32 km. An analysis of the morphology of the scarps and sections indicates that the dislocations were formed as a result of at least 2–3 paleoearthquakes with a magnitude of 7.0–7.2. According to the data of absolute (radiocarbon) and relative (according to the slope of the scarps) dating, the age of paleoearthquakes lies in the intervals of 5–8 ka, 2373–2832 years ago and later than 760 years ago. The high seismic potential of the fault revealed by seismogeological data is confirmed by historical evidence of the occurrence here a M=6.0 earthquake in 1830.