Correlation of foreshocks and aftershocks and asperities |
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Authors: | Vindell Hsu Charles E. Helsley Eduard Berg David A. Novelo-Casanova |
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Affiliation: | (1) Hawaii Institute of Geophysics, University of Hawaii, 2525 Correa Road, 96822 Honolulu, Hawaii |
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Abstract: | A close correlation in spatial distribution of local seismic activity and energy release patterns before and after the 1979 Petatlan, Mexico earthquake suggests heterogeneity within the fault plane of this major low-angle thrust event associated with subduction along the Middle America Trench. A simple two-asperity model is proposed to account for the complexity. Foreshocks and aftershocks of the neighboring 1981 Playa Azul earthquake showed a similar pattern. As both events occurred at the junction of the Orozco Fracture Zone and the Middle America Trench, we speculate that the observed complex fault plane is caused by subduction of the rugged ocean floor of the Orozco Fracture Zone. Short-term precursory seismicity prior to the Petatlan earthquake can be explained by using the asperity model and migration of a slip front from the south-east to the north-west across the main shock source region. |
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Keywords: | Petatlan earthquake Foreshocks and aftershocks Asperities |
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