Reinterpretation of Historical Earthquakes during 1929 TO 1931, Myanmar
Abstract
The years between 1929 to 1931 are significant years for Myanmar region, with a series of earthquakes starting with Swa Earthquake in 1929 to Phyu Earthquake in 1931. Major earthquakes that occurred during the years 1929 to 1931 in the past are in a remarkably linear distribution along the Sagaing fault. The area along the Sagaing fault falls in Zone 1 of the Seismic Zones of Myanmar. A detailed study of the Sagaing fault through the satellite images and aerial photographs reveals a zigzag nature consisting of alternate long NNW-SSE striking and short ENE-WSW striking fracture lineaments. The former occurs in a right-handed en-echelon strike-slip pattern which are cut by the latter being expressed as a normal fault character. The presence of dominant ENEWSW striking normal faults suggest that the area has been experiencing NNW-oriented regional tensional stress. Locations of historical earthquakes for the years of 1929 to 1931 have defined two ruptured segments viz. Segment (1) and Segment (3). Since 1929, earthquakes were mainly occurring in the southern and northern parts of the Sagaing fault. Therefore, it can be inferred that until end of 1991, the seismic activity was mostly confined on Segment (1) and Segment (3). To better examine the relationship between the seismicity and tectonics, major historical earthquakes of Pyinmana (1931), Pegu (Bago) (1930), Phyu (1930) and Swa (1929) are grouped as Segment (1) and Tagaung (1991), Mandalay (1956), Wuntho (1946) and Kamaing (1931) as Segment (3). The remaining unruptured fault length about 200 km in between these two segments is Segment (2). A detailed study of characteristics of each earthquake show that periodic movement along the normal lineaments has given rise to seismicity, and the location of earthquake events coincides with zones of lateral dislocation of Sagaing fault and occurrence of localized ridges or localized basins in the fault zone.
- Publication:
-
Advances in Geosciences, Volume 31: Solid Earth Science (SE)
- Pub Date:
- October 2012
- DOI:
- 10.1142/9789814405775_0005
- Bibcode:
- 2012aogs...31...43A