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1 URS Corporation
566 El Dorado
Street
Pasadera, California
91101
chandan_saikia{at}urscorp.com
The primary objective of this study is to model regional and far-regional
seismograms recorded from the 21 May 1997 Jabalpur earthquake
(Mw 5.8) in central India to calibrate the propagation path
in and around the Indian subcontinent. To accomplish this goal, we first
established its source parameters (
= 65°,
= 68°, and
= 70°,
h = 35 km) and source complexity, which consisted of two sources
with a total seismic moment of 5.88 x 1024 dyne cm and a source
1 to source 2 moment ratio of 1:4 by modeling teleseismic P and depth
phases. Source parameters were independently verified by modeling near-regional
seismograms of three stations, namely BHPL (Bhopal), BLSP
(Bilaspur), and HYB (Hyderabad), by using the same source complexity
established in the teleseismic modeling and station-specific wave-propagation
path models. The earthquake was relocated by fixing its depth at 35 km and using
travel times of teleseismic P, pP, sP phases and regional P
and S phases. The International Association of Seismology and Physics
of the Earths Interior model was used for the location with its crust
replaced by the regionalized crustal model. The relocation parameters were:
origin time, 22h51m30.80sec ± 0.83 sec; latitude, 23.083° N;
longitude, 80.091° E; h = 35 km. With this relocation,
source-specific station corrections were established that, in turn, were used to
relocate its largest aftershock. Next, we analyzed the composition of regional
phases to understand how they were excited, especially how up-going and
down-going seismic waves evolved and interfered as a function of distance. This
understanding and the newly derived source information were used to calibrate
station-specific paths to other far-regional and upper-mantle stations. To this
end, we modeled amplitude and travel times of different phases, such as the
Pnl, S, SmS,
Sm(up)S, and surface waves observed at far-regional
stations (5°
25°). This study established far-distance
wave-propagation models for paths toward CHTO (Chiang Mai, Thailand), LSA
(Lhasa, China), and AAK (Ala-Archa, Kyrgyzstan). We also calibrated a
wave-propagation model for a path from northwest India to station NIL (Nilore,
Pakistan) using seismograms recorded from an earthquake near Pokhran, the
nuclear test site in India.
This article has been cited by other articles:
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S. K. Singh, S. D. Pimprikar, B. K. Bansal, J. F. Pacheco, R. S. Dattatrayam, and G. Suresh An Analysis of the Mw 4.7 Jabalpur, India, Earthquake of 16 October 2000: Toward Ground-Motion Estimation in the Region from Future Events Bulletin of the Seismological Society of America, October 1, 2007; 97(5): 1475 - 1485. [Abstract] [Full Text] [PDF] |
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