Improved earthquake locations in the Koyna-Warna seismic zone |
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Authors: | P Rajagopala Sarma D Srinagesh |
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Institution: | (1) National Geophysical Research Institute, Uppal Road, Hyderabad, 500007, India |
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Abstract: | In estimating the likelihood of an earthquake hazard for a seismically active region, information on the geometry of the potential
source is important in quantifying the seismic hazard. The damage from an earthquake varies spatially and is governed by the
fault geometry and lithology. As earthquake damage is amplified by guided seismic waves along fault zones, it is important
to delineate the disposition of the fault zones by precisely determined hypocentral parameters. We used the double difference
(DD) algorithm to relocate earthquakes in the Koyna-Warna seismic zone (KWSZ) region, with the P- and S-wave catalog data
from relative arrival time pairs constituting the input. A significant improvement in the hypocentral estimates was achieved,
with the epicentral errors <30 m and focal depth errors <75 m i.e. errors have been significantly reduced by an order of magnitude
from the parameters determined by HYPO71. The earthquake activity defines three different fault segments. The seismogenic volume is shallower in the south by 3 km,
with seismicity in the north extending to a depth of 11 km while in the south the deepest seismicity observed is at a depth
of 8 km. By resolving the structure of seismicity in greater detail, we address the salient issues related to the seismotectonics
of this region. |
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Keywords: | Double difference Fault segmentation Focal mechanism Koyna-Warna |
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