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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References
Bakun, W. H. (1984),Seismic Moments, Local Magnitudes and Coda Duration Magnitudes for Earthquakes in Central California, Bull. Seismol. Soc Am.74, 439–458.
Bhattacharya, S. N. (1981),Observation and Inversion of Surface Wave Group Velocities across Central India, Bull. Seismol. Soc. Am.71, 1481–1501.
Bhattacharya, S. N. (1992a),Similarity of Lithospheric Structure of Central and Northwestern Part of the Indian Peninsula Inferred from the Observed, Surface Waveforms, Mausam43, 51–58.
Bhattacharya, S. N. (1992b),Generation of Synthetic Seismograms with Layer Reduction, Geophys. J. Int.111, 79–90.
Brüstle, W., andMüller, G. (1983),Moment and Duration of Shallow Earthquakes from Love-wave Modelling for Regional Distances, Phys. Earth Planet. Interiors32, 312–324.
Chandra, U. (1977),Earthquakes of Peninsular India — A seismotectonic Study, Bull. Seismol. Soc. Am.67, 1387–1413.
Gupta, I. D., Rambabu, V., andJoshi, R. G. (1993),Strong Earthquake Ground Motion Data in EQINFOS for India: Part 1A Report CE 93-03, CWPRS, Pune.
Helmberger, D. H., andMalone, S. D. (1975),Modelling Local Earthquakes as Shear Dislocation in a Layered Half Space, J. Geophys. Res.80, 4881–4888.
Herrmann, R. B., andWang, C. Y. (1985),A Comparison of Synthetic Seismograms, Bull. Seismol. Soc. Am.75, 41–56.
Hwang, H. J., andMitchell, B. J. (1987),Shear Velocities, Q β and the Frequency Dependence of Q β in Stable and Tectonically Active Regions from Surface Wave Observations, Geophys. J.90, 575–613.
Kind, R., andOdam, R. I. (1983),Improvement to Layer Matrix Methods, J. Geophys.53, 127–130.
Knopoff, L., Schwab, F., andKausel, E. (1973),Interpretation of Lg, Geophys. J.33, 387–402.
Langston, C. A. (1976),A Body Wave Inversion of the Koyna, India Earthquake of December 10, 1967 and Some Implications for Body Wave Focal Mechanisms, J. Geophys. Res.81, 2517–2529.
Langston, C. A. (1985),Source Inversion of Seismic Waveforms: The Koyna, India Earthquakes of 13 Sep. 1967, Bull. Seismol. Soc. Am.71, 1–24.
Langston, C. A. (1985),Modelling of the Koyna, India, Aftershock of 12 December 1967, Bull. Seismol. Soc. Am.75, 651–660.
Lee, W. H. K., andLahr, J. C. (1975),Hypo 71 (Revised): A Computer Program for Determining Hypocenter, Magnitude and First Motion Pattern of Local Earthquakes, U.S. Geol. Surv., Open File Report 75-311.
Press, F., andEwing, M. (1952),Two Slow Surface Waves Across North America, Bull. Seismol. Soc. Am.43, 219–228.
Rastogi, B. K., andTalwani, P. (1980),Relocation of Koyna Earthquakes, Bull. Seismol. Soc. Am.70, 1849–1868.
Rastogi, B. K., Chadha, R. K., andRaju, I. P. (1986),Seismicity near Bhatsa Reservoir, Maharashtra, India, Phys. Earth Planet. Interiors44, 179–199.
Rastogi, B. K. (1992),Seismotectonics Inferred from Earthquakes and Earthquake Sequences in India during the 1980s, Current Sci.62, 101–108.
Richter, C. F.,Elementary Seismology (W. H. Freeman, San Francisco 1958).
Somerville, P. G., McLaren, J. P., LeFevre, L. V., Burger, R. W., andHelmberger, D. V. (1987),Comparison of Source Scaling Relations of Eastern and Western North American Earthquakes, Bull. Seismol. Soc. Am.77, 322–346.
Tandon, A. N., andChaudhury, H. M. (1968),Koyna Earthquake of December 1967, India Met. Dept, Sci. Report59.
Thatcher, W., andHanks, T. C. (1973),Source Parameters of Southern California Earthquakes, J. Geophys. Res.78, 8547–8576.
Woods, B. B., Kedar, S., andHelmberger, D. V. (1993),M L :M 0 as a Regional Seismic Discriminant, Bull. Seismol. Soc. Am.83, 1167–1183.
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Bhattacharya, S.N. Determination of source duration and moment of earthquakes in the Indian Peninsula using love waveforms. PAGEOPH 147, 497–514 (1996). https://doi.org/10.1007/BF00878841
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DOI: https://doi.org/10.1007/BF00878841