Discrimination Underground Explosions from Earthquakes Using Seismic Coda Waves
Annual technical rept. 1 Nov 1992-31 Oct 1993
UNIVERSITY OF SOUTHERN CALIFORNIA LOS ANGELES DEPT OF GEOLOGICAL SCIENCES
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The objective of this study is to discriminate the explosions and earthquakes at regional distance by using the coda wave method. In an earlier study, Su and Aki 1991 found a significant difference in coda attenuation, Qc- 1, for quarry blasts and earthquakes at frequencies of 1.5 and 3 Hz for lapse time less than 30 seconds and they suggested that such a significant difference in Qc-1 may be attributed to the seismic surface waves contributions. To interpret the observed seismic coda waves we need to consider the seismic surface wave scattering processes. Wu 1985 and Zeng et al. 1991, 1993 have shown that the energy transfer theory can successfully describe the seismic body waves scattering processes in a random scattering and absorption full-space medium. In this study, we shall first use the energy transfer equations to study the seismic surface waves scattering processes and the surface wave with body waves scattering processes in order to interpret the Su and Akis observed results. We shall then extend this method to study the explosions and earthquakes at regional distance.