Morphology of the subducted Indian plate in the Indo-Burmese convergence zone
- 75 Downloads
Earthquake hypocenters and travel time residuals have been analysed to constrain the geometry and physical state of the subducted Indian plate in the Indo-Burmese convergence zone. A critical analysis of earthquake hypocenters reveals the existence of a non-uniform Benioff zone, progressively shortening from north to south. The deepest level of seismicity is observed beneath the Naga hills (160 km) followed by that under the Chin hills (120 km) and Arakan-Yoma ranges (80 km). The region seems to be devoid of moderate sized shallow (< 40 km) earthquakes. Differential travel time residuals from pairs of shallow and intermediate depth earthquakes recorded at teleseismic distances show significantly faster travel time (up to l.2s) in the north-northeast and south-southwest azimuths, whilst slower arrivals (1.2 to 1.5 s) are recorded in the transverse direction. This observation points to the presence of a high velocity slab possibly linked to the subduction of the Indian oceanic lithosphere.
KeywordsBenioff zone hypocenter subduction travel time residual Indo-Burmese range
Unable to display preview. Download preview PDF.
- Anonymous Users Guide to FAISE: Retrieval Software for the ISC Bulletin Data Base Version 1.0 U.S. Geological Survey, National Earthquake Information Center, Golden, CO, USAGoogle Scholar
- Brunnschweiler R O, On the geology of the Indo-Bunnan ranges;J. Geol. Soc. Aust. 13, 137–194Google Scholar
- Barazangi M and Isacks B L 1979 Subduction of the Nazca plate beneath Peru: evidence from spatial distribution of earthquakes;Geophys. J. R. Astron. Soc. 57 537–555Google Scholar
- Davies D and McKenzie D P 1969 Seismic travel-time residuals and plates.Geophys. J. R. Astron. Soc. 18 51–63Google Scholar
- Hasegawa A, Umino, N and Talcagi A 1978 Double-planned deep seismic zone and upper mantle structure in the northeastern Japan arc;Geophys. J. R. Astron. Soc. 54 281–296Google Scholar
- Isacks B and Barazangi M 1977 Geometry of Benioff zones: Lateral segmentation and downwards bending of the subducted lithosphere; Island Arcs, Deep sea trenches and Back arc basins, (eds.) M Talwani and W Pitman (American Geophysical Union), Ewing series 1, 99–114Google Scholar
- Jackson J 1980 Errors in focal depth determination and the depth of seismicity in Iran and Turkey;Geophys. 43 J. R. Astron. Soc. 61 285–301Google Scholar
- Jeffreys H and Bullen K E 1940 Seismological table, British Association for the Advancement of ScienceGoogle Scholar
- Jordan T H 1977 Lithospheric slab penetration into lower mantle beneath the sea of Okhotsk;J. Geophys. 43 473–496Google Scholar
- Santo T 1969 Regional study of the characteristic seismicity of the world, II, from Burma down to Java;Bull. Earthquake Res. Inst. Tokyo 47 1049–1061Google Scholar