Focal depth information from the SH body wave spectrum of a deep earthquake

Abstract

Summary- The SH body-wave spectrum of a deep earthquake, which occurred at the foot of the Kamchatka peninsula and was recorded in the Solomon Islands, presents a regular modulation. The distribution of minima in the amplitude spectrum, corresponding to jumps in the phase spectrum, conforms with that expected from the interference between direct and surface reftected waves. The strong dependence of the modulation on the focai depth, emerging from theoretica1 SH body wave spectra obtained with the contribution of the first 21 higher Love-wave modes, was used to investigate the focai depth of the event here considered. The value estimated, 140 km, agrees with an earlier focal depth determination by travel time data.