科研之友
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摘要
High-frequency S-wave seismogram envelopes of microearthquakes are broadened with increasing travel distance, which is called S-wave envelope broadening. Multiple forward scattering and diffraction induced by random inhomogeneities along seismic ray path are the main reasons to cause the S-wave envelope broadening, so the phenomena of S-wave envelope broadening can be used to study the medium inhomogeneity. The peak delay time of S-wave, which is defined as the time lag from the direct S-wave onset to the maximum amplitude arrival of its envelope, was accepted to quantify the phenomena of S-wave envelope broadening. The medium inhomogeneity of crust in Changbaishan Tianchi volcano area, based on analyzing small local earthquakes waveform was studied by the peak delay time of S-wave envelope broadening method. The results show that the medium of Changbaishan Tianchi volcano area presents strong inhomogeneity, the spatial distribution characters of inhomogeneous medium in the south are stronger than that in the north region of Changbaishan Tianchi volcano area at the depth of 0 similar to 2 km, and the spatial distribution characters of inhomogeneous medium at the depth of 2 similar to 5 km depend on frequency. The medium inhomogeneity in Changbaishan Tianchi volcano area presents multi-scale character. Earthquakes usually occur around the contact band of the strong and the weak inhomogeneity. We believe that the medium inhomogeneity of crust in Changbaishan Tianchi volcano area may reveal the difference of early erupted material properties according to the relative spatial position of earthquakes and inhomogeneities.
- 出版日期2009-10
- 单位江苏省地震局; 中国地震局
