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Seismicity, gravity anomalies and lithospheric structure of the Andaman arc, NE Indian Ocean

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Title Seismicity, gravity anomalies and lithospheric structure of the Andaman arc, NE Indian Ocean
 
Creator RADHAKRISHNA, M
LASITHA, S
MUKHOPADHYAY, M
 
Subject 26 december 2004
subduction zone
deep-structure
emplacement history
satellite altimetry
tectonic evolution
sumatra earthquake
ninetyeast ridge
sunda trench
island-arc
andaman arc
slab-residual gravity anomaly
mantle bouguer anomaly
lithosphere structure
seismicity
indian ocean
 
Description The Andaman arc in the northeastern Indian Ocean defines nearly 1100 km long active plate margin between the India and Burma plates where an oblique Benioff zone develops down to 200 km depth. Several east-trending seismologic sections taken across the Andaman Benioff Zone (ABZ) are presented here to detail the subduction zone geometry in a 3-D perspective. The slab gravity anomaly, computed from the 3-D ABZ configuration, is a smooth, long-wavelength and symmetric gravity high of 85 mGal amplitude centering to the immediate east of the Nicobar island, where, a prominent gravity "high" follows the Nicobar Deep. The Slab-Residual Gravity Anomaly (SRGA) and Mantle Bouguer Anomaly (MBA) maps prepared for the Andaman plate margin bring out a double-peaked SRGA "low" in the range of -150 to -240 mGal and a wider-cum-larger MBA "low" having the amplitude of -280 to -315 mGal demarcating the Andaman arc-trench system. The gravity models provide evidences for structural control in propagating the rupture within the lithosphere. The plate margin configuration below the Andaman arc is sliced by the West Andaman Fault (WAF) as well as by a set of sympathetic faults of various proportions, often cutting across the fore-arc sediment package. Some of these fore-arc thrust faults clearly give rise to considerably high post-seismic activity, but the seismic incidence along the WAF further east is comparatively much less particularly in the north, although, the lack of depth resolution for many of the events prohibits tracing the downward continuity of these faults. Tectonic correlation of the gravity-derived models presented here tends to favour the presence of oceanic crust below the Andaman-Nicobar Outer Arc Ridge. (c) 2008
 
Publisher ELSEVIER SCIENCE BV
 
Date 2011-07-26T15:48:15Z
2011-12-26T12:55:00Z
2011-12-27T05:43:30Z
2011-07-26T15:48:15Z
2011-12-26T12:55:00Z
2011-12-27T05:43:30Z
2008
 
Type Article
 
Identifier TECTONOPHYSICS, 460(1-4), 248-262
0040-1951
http://dx.doi.org/10.1016/j.tecto.2008.08.021
http://dspace.library.iitb.ac.in/xmlui/handle/10054/6950
http://hdl.handle.net/10054/6950
 
Language en