Source time-function as discriminant using empirical Green's function

摘要

The source mechanism of underground nuclear explosions is remarkably different from that of earthquakes in both spatial radiation pattern and source time-function (STF). Small underground nuclear explosions can be used as empirical Green's functions (EGF) to isolate the source-time spectrum of a large suspected earthquake occurred in a Nuclear Test Site (target area) by the spectral division method. As this study shows, with high-quality data, the quotient spectrum can be transformed to the time domain, yielding the apparent far-field source-time function of the large suspected event. The relative source time-function (RSTF) of a nuclear explosion is usually a simple pulse with a duration of about 1 s., while an earthquake's is more complicated with a series of pulses and a longer duration. The RSTF can be used as a nice discriminant to distinguish the nature earthquakes from underground nuclear explosions in target areas.