Paleoseismological and archaeoseismological data from the western Alabash-Konurolen intramontane basin (southern Lake Issyk Kul area, Kyrgyzstan)

Paleoseismological and archaeoseismological studies have furnished proof that the northern border of the Alabash-Konurolen basin is thrusting over the basin sediments. The sediments store a record of two earthquakes that occurred between 8400 and 7300 yr BP and presumably in the 16th century. The minimum magnitude of the latter earthquake was estimated, based on the length (2.3 km) of the fault scarp it produced and the amount of displacement (0.4 m) on the respective reverse plane, to range within 6.6-6.8. The older event was of about the same minimum magnitude. The results call for a revision of the existing seismic risk division of Kyrgyzstan that places the Alabash-Konurolen basin into a zone of M ≤ 6.5 seismicity.