Abstract

We demonstrate a case of using short-period, vertical-component seismograms alone to study the Archean crust. The approach is equivalent to conventional seismic reflection profiles except that high-frequency (up to 1.2 Hz) transmitted wave fields from earthquakes are used as natural sources. On seismic sections from the Gauribidanur Array (gba), reflection off the Moho (PpPmp phase) stands out and indicates a sharp, subhorizontal Moho. From known crustal thickness of 36 ± 2 km, our results show an average value of 6.55 ± 0.37 km/sec for P-wave speed in the crust. Recent results from receiver functions collectively imply an intermediate to felsic bulk composition for the Archean crust in southern India.

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