Open AccessSeismicity, Earthquake Mechanisms and Tectonics of Burma, 20°N‐28°N
Author(s) -
Chandra Umesh
Publication year - 1975
Publication title -
geophysical journal of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.302
H-Index - 168
eISSN - 1365-246X
pISSN - 0016-8009
DOI - 10.1111/j.1365-246x.1975.tb04138.x
Subject(s) - geology , seismology , induced seismicity , focal mechanism , tectonics , aftershock , burmese , plate tectonics , compression (physics) , thrust fault , clockwise , fault (geology) , subduction , slip (aerodynamics) , eurasian plate , fold (higher order function) , mechanical engineering , linguistics , philosophy , materials science , physics , engineering , composite material , thermodynamics
Summary Hypocentre data file compiled by the Environmental Research Laboratories (ERL) of the US Geological Survey was used to prepare seismicity maps of the region for the periods, January 1900 to June 1973, and January 1963 to June 1973. Most of the earthquakes occur in the Arakan Yoma range and the Burmese central belt. In the northern part of the region, north of 24° N, the foci tend to occur in two zones converging beneath the Chindwin river. One zone dips in the direction S 44° E at an angle of about 29° and the other zone dips in the direction N 50° W at an angle of about 51°. South of 24° N, earthquakes occur in a slab dipping due east at an angle of about 47°. Focal mechanism solutions for eight earthquakes occurring between January 1964 to December 1971 have been determined by using P ‐wave polarity and S ‐wave polarization data. South of 24° N, one normal and two thrust fault plane solutions indicate underthrusting of the Indian plate towards east along the Burmese arc. An exception is the earthquake of 1969 October 17. It has a well‐determined thrust fault plane solution and is caused by north‐south compression. Further north, due to the complexity of tectonics caused by the syntaxial bend of the Himalayan and Burmese mountain ranges, the axes of maximum compression for two events are parallel rather than perpendicular to the local structural trend. Two shallow focus events occurring near the south‐eastern flank of the syntaxis have strike slip mechanism solution.