Source-mechanism from spectra of long-period seismic surface-waves: 1. The Mongolian earthquake of December 4, 1957
- Creators
- Ben-Menahem, Ari
- Toksöz, M. Nafi
Abstract
The Pasadena seismograms of the Mongolian earthquake of December 4, 1957, were studied. Mantle Rayleigh waves R_3, R_4, R5, and R_6 were separated, digitized, filtered, and Fourier-analyzed. After the evaluation of the phase velocities and the absorption coefficients from amplitude ratios R_3/R_5 and R_4/R_6 the directivity was computed from the amplitude ratio of R_3/R_4. A fault of 560 km, with an azimuth of 100°, and a rupture velocity of 3.5 km/sec gave the best fit to the observed directivity. Auxiliary data from aftershock distribution, initial motions, air waves from the main shock, and geological surveys of the fault area seem to support these findings. The phase spectra of R_3 and R_4 were corrected for the propagation phase and the instrumental phase shift to obtain the initial phases at the source. A rough estimate of the depth of faulting is obtained on the basis of the calculated strain release and observed displacements at the fault.
Additional Information
Copyright 1962 by the American Geophysical Union. Manuscript received December 22, 1961; revised February 7, 1962. This research was supported by Contract Af-49 (638) 910 of the Air Force Office of Scientific Research as part of the Advanced Research Projects Agency project VELA. We wish to thank Dr. Stewart W. Smith and Mr. Shelton S. Alexander for helping us with the digital analysis. Acknowledgments also due Gilbert Dewart for translation of a foreign text, and Laszlo Lenches who drew the figures. Group velocities in Figure 9 were computed by Eli Arieh and Don L. AndersonAttached Files
Published - jgr2708.pdf
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Additional details
- Eprint ID
- 47853
- Resolver ID
- CaltechAUTHORS:20140801-160729185
- AF-49 (638) 910
- Air Force Office of Scientific Research (AFOSR)
- Advanced Research Projects Agency (ARPA), project Vela
- Created
-
2014-08-04Created from EPrint's datestamp field
- Updated
-
2021-11-10Created from EPrint's last_modified field
- Other Numbering System Name
- Caltech Division of Geological Sciences
- Other Numbering System Identifier
- 1052