Source parameters of earthquake and landslide events occurring at the eastern Himalayan syntaxis
Abstract
The eastern Himalayan sytaxis is located at the northeastern corner of the Himalayan collision zone where the Indian plate underthrusts beneath the Eurasian plate. Here the crustal shortening and the tectonically rotated deformation is the strongest with respect to other areas along the Himalayan orogenic belt. Because of the active tectonics and the heavy rains during the Indian monsoon season, earthquake and landslide events occur frequently. These events often cause severe damage to lifeline facilities, blockage of the Yarlung-Tsangpo river and rise of high water levels. Due to the harsh environment of the study area, seismic stations are difficult to install . The source parameters of these events are either highly uncertain or previously undetected. Based on the seismic stations we deployed around the eastern Himalayan sytaxis, we studied the source parameters of several recent earthquake and landslide events.
On November 18 2017, an Ms6.9 earthquake occurred in Mainling prefecture. It is primarily thrust faulting with a strike-slip component. Aftershocks are mainlydistributed along a NW-SE direction over an area of 40 km×10 km. From NW to SE, aftershocks gradually concentrated closer to the Xixingla fault. The focal mechanisms of relatively large earthquakes in the region are mostly strike-slip faulting. In October 2018, two landslide events occurred in Mainling prefecture. The direct P- and S-waves for these events are not clear but there are relatively large amplitude surface waves. These events are caused by breaking of a glacier, followed by a chain of landslides along the valley, and blockage of the Yarlung-Tsangpo river. On April 24 2019, an Ms6.3 earthquake occurred in Medog prefecture. The large slip is mainly concentrated near the hypocentral area. The major tectonic feature of this earthquake is the west-dipping thrust of the lesser Himalaya beneath the Namche Barwa at the Main Himalayan Thrust.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.T41E0327B
- Keywords:
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- 1242 Seismic cycle related deformations;
- GEODESY AND GRAVITY;
- 7230 Seismicity and tectonics;
- SEISMOLOGY;
- 8004 Dynamics and mechanics of faulting;
- STRUCTURAL GEOLOGY;
- 8123 Dynamics: seismotectonics;
- TECTONOPHYSICS