Ray Weldon from the University of Oregon will talk about How better geology can improve seismic hazard estimates in Kyrgyzstan. The webinar is open for everyone interested and will be held via zoom (https://uni-jena-de.zoom.us/j/8941887790 Meeting-ID: 894 188 7790; Password: 820815).
Date: 22 February, 2021
Time: 3 pm GMT (7 am San Francisco; 3 pm London; 4 pm Berlin & Paris; 8:30 pm Delhi; 9 pm Almaty; 11 pm Beijing)
The Tien Shan takes up about 20 mm/yr of N-S shortening as a result of the India-Eurasia convergence. Recent paleoseismological studies have shown that the shortening is accommodated by a large number of faults, whose slip rates are relatively low. Although the historical earthquake catalogues only reach back a few hundred years, we know that the Tien Shan has seen some of the strongest intracontinetal quakes world-wide with magnitudes exceeding M8. Paleoseismological studies have revealed a large number of surface-rupturing earthquakes, too. But the question is: Do all these known faults rupture in strong earthquakes? In a recent paper, my colleagues and I argue that there is at least one major fault in the Northern Tien Shan that is creeping (Mackenzie et al., 2018). more
Between 1885 and 1938, the northern Tien Shan at the border between present Kyrgyzstan and Kazakhstan experienced a remarkable series of five major earthquakes, exceeding M6.9 and reaching up to M ~ 8 (1885 Belovodskoe M6.9, 1887 Verny M7.3, 1889 Chilik M~8, 1911 Chon Kemin M8, and 1938 Kemino Chu M6.9). Combined, the seismic moments add up to almost moment magnitude 9, which is a significant amount of strain released in roughly 50 years and across an E-W stretch of less than 500 kilometers. Even more intriguing is the fact that the ruptured region is located more than thousand km north of the nearest plate boundary and associated India-Eurasia collision zone. The macroseismic areas of these earthquakes include the present-day capital of Kyrgyzstan, Bishkek (Frunze) and the former capital and still largest city of Kazakhstan, Almaty (earlier names Alma Ata and Verny).