Determination of source duration and moment of earthquakes in the Indian Peninsula using love waveforms |
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| Authors: | S N Bhattacharya |
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| Institution: | (1) Seismological Observatory, India Meteorological Department, Lodi Road, 110003 New Delhi, India |
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| Abstract: | Love waves recorded by a long-period seismograph at New Delhi (NDI) from seven earthquakes of magnitude 4.3 to 5.2 in Koyna and Bhatsa on the western coast and one earthquake in Ongole on the eastern coast of the Indian Peninsula have been used to determine the seismic moment for each of the earthquakes by waveform modeling. Transverse component of the synthetic seismogram shows that the maximum amplitude of waveform decreases with an increase of source duration. Thus for an evaluation of the seismic moment by equating the amplitude level of the observed and synthetic waveforms, we must know the source duration. The synthetic seismogram also indicates that a short source duration gives rise to a small but sharp pulse and this pulse is interpreted as anLg wave. Comparison of the observed and synthetic waveforms has been used for a simultaneous evaluation of the source duration and seismic moment. The source durations are found to vary between 2.2 and 4.4 s; for earthquakes with a magnitude range between 4.3 and 5.2 these durations are slightly higher than normal. We obtain moment (M
0) of Ongole earthquake (M
L
=5.1)as 1.7×1024 dyne-cm; moments of Koyna and Bhatsa earthquakes (4.3 M
L
5.2) on the western coast lie between 0.7×1023 and 3.6×1023 dyne-cm. Moment (M
0)-magnitude (M
L
) relation logM
0=1.5M
L
+16.0 for the western United States region agrees as well, in general, with the results for the earthquakes in the Indian Peninsula. |
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| Keywords: | Seismic moment source duration Love waveforms |
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