Surface coseismic gravity changes caused by dislocations in a 3-D heterogeneous earth |
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Authors: | Guangyu Fu Wenke Sun |
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Affiliation: | Earthquake Research Institute, the University of Tokyo, Yayoi 1-1-1, Bunkyo, Tokyo, Japan. E-mail: |
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Abstract: | This study describes an examination of surface gravity changes caused by dislocations within a 3-D heterogeneous earth. This new theory is described using six independent dislocations: a vertical strike-slip, two vertical dip-slips perpendicular to each other, and three tensile openings on three perpendicular planes. A combination of the six independent dislocations is useful to compute coseismic gravity changes resulting from an arbitrary seismic source at an arbitrary position. Based on the 3-D lateral inhomogeneous P -wave velocity model, we deduce the 3-D density and S -wave velocity models using the relation of Karato. Finally, numerical computations are performed for a location south of Japan (30°N, 135°E). We calculate the coseismic gravity changes resulting from the six independent dislocations for source depths of 100, 300 and 637 km, respectively. Numerical results show that the maximum 3-D effect varies concomitantly with the dislocation type and the source depth. For seismic problems, the effect of elastic parameter μ is dominant. |
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Keywords: | Gravity anomalies and Earth structure Geopotential theory Theoretical seismology |
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