Abstract

Teleseismic body waves from the 14 September 1981 eastern Hispaniola earthquake were inverted using different source structure models. Comparison of the inversion results showed that the non-double-couple (CLVD) component of the moment tensor may be interpreted as a measure of deficiencies in the inversion procedure. Increasing the complexity of the source structure model to improve the fit of the Green's functions to the observed seismograms, improving the data set's azimuthal coverage, and leaving the time function free to compensate partially for the deficiencies of the Green's functions all can decrease the size of the CLVD component. For an earthquake in which the direct arrival is clearly separated from the crustal phases, an inversion of the direct P and SH waves only, assuming a half-space source structure model, is adequate to determine the source double-couple orientation and time function. The moment tensor for the Hispaniola earthquake indicates thrust faulting on an east-west striking fault plane dipping 30° to 35° to the south. The pressure axis is oriented north-south, the intermediate axis east-west, and the tension axis is nearly vertical. The source time function is a simple 3-sec-long triangular pulse. The slip vector is consistent with the slip vectors for nearby earthquakes, as determined in other studies and indicates that the slab is moving down-dip to the south.

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