Seismological Research Letters; March/April 2009; v. 80; no. 2;
p. 233-242; DOI: 10.1785/gssrl.80.2.233
© 2009 Seismological Society of America
Ground Motion Synthesis and Seismic Scenario in Guwahati City—A Stochastic Approach
S. K. Nath,
A. Raj,
K. K. S. Thingbaijam, and
A. Kumar
Indian Institute of Technology
Kharagpur
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INTRODUCTION
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Guwahati is fast emerging as a multi-ethnic cosmopolitan city with a
burgeoning population and rapid unplanned urbanization. It is a commercial
hub, catering to eight states in northeast India. The city is located in the
lower Brahmaputra Valley and underlain by thick alluvial deposits ranging from
25 to 600 m with granitic exposure at places. The regional seismotectonics of
northeast India exhibit a rather large potential for high-magnitude
earthquakes, as reported by Thingbaijam et al.
(2008). Large earthquakes in
the past caused widespread damage to life and property in this terrain.
Presently, the urban agglomeration in this area is quite vulnerable to
possible future great earthquakes. Given the devastation caused recently by
the Sichuan earthquake of 12 May 2008 (MW 7.9), with a
death toll of nearly 70,000 and loss of property worth billions of dollars, it
is imperative that we have a realistic hazard scenario for this extremely
vulnerable seismic province.
Seismic hazard quantification at a site is based, essentially, on
understanding the site response and the propagation path of seismic waves, as
well as the source characterization of a damaging earthquake. A typical
deterministic seismic hazard model takes these physical attributes into
account while estimating peak ground acceleration (PGA).
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Figure 1. Seismotectonic map of northeast India adapted from Thingbaijam
et al. (2008) wherein
the fault rupture zones of four scenario earthquakes have been depicted with
rectangular polygons.
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The results of the simulations of four scenario earthquakes based on four
large historical earthquakes in the region have been reported here. An
extended finite-fault stochastic modeling approach has been adapted for strong
ground-motion synthesis for the predicted maximum earthquakes in the terrain
as reported by Thingbaijam and Nath
(2008). An attempt also has
been made to establish regional as well as site-specific attenuation relations
for . . . [Full Text of this Article]
Indian Institute of Technology
Kharagpur 721302
West
Bengal, India
nath@gg.iitkgp.ernet.in
(S. K. N.)
Copyright © 2009 by Seismological Society of America