The 2022 Twin Earthquakes and Tectonic Environment in Kyaing Tong Basin, Eastern Myanmar

The first earthquake of magnitude 4.8 struck at 57 km south of Kyaing Tong, latitude 21.1141°N longitude 99.850°E, on 21st July 2022, at 16:40:08 UTC ( 11:07 a.m. local time ) at the depth of 10 km. Immediately after 30 minutes on the same day of 21st July 2022, the second earthquake with magnitude 5.9 occurred, 53 km south of Kyaing Tong at latitude 21.150°N 99.863°E, 17:07:26 UTC (11:37 a.m. local time) at 10 km depth. Focal mechanism solution for the first event was left-lateral strike-slip faulting and the second by normal faulting with a component of strike-slip component (United States Geological Survey). Many lesser aftershocks followed the main shocks and continued since July and still ongoing up to date in 2022. Twin earthquakes ruptured along the Wan Ha fault which bounds the southeast side of the Kyaing Tong basin, eastern Myanmar. The rupture propagated southward. The Kyaing Tong basin is one of the tectonic basins in the Paleo-Tethys suture zone in eastern Myanmar. These earthquakes are due to the movement of Wan Ha fault, affected the town Kyaing Tong where it caused some houses and schools collapsed. No casualty was reported. According to data from USGS, and other earthquake agencies, there is a clear increase in detected earthquakes, particularly smaller quakes of magnitude around ≥ 1.0 and ≥ 2.0 at shallower depth of 1000 meter. From the studies of satellite images, aerial photographs, shaded relief map and Digital Elevation Model map, several lineaments are visible and detailed mapping of these lineaments show the strike-slip faults in ENE-WSW direction and normal faults in NE-to NNE-striking direction. NW-SE extension is evident by the occurrence of brittle normal faults and NE-to ENE-oriented sinistral strike-slip fault. Within this zone is the trace of regional compression in a NE-SW direction. This region is presently undergoing active tectonic deformation, as indicated by current seismicity and earthquake focal mechanism solution.