Open AccessRadiation pattern of crustal phases of New England earthquakes
Author(s) -
Zhao Xiaomin,
Ebel John E.
Publication year - 1991
Publication title -
geophysical journal international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.302
H-Index - 168
eISSN - 1365-246X
pISSN - 0956-540X
DOI - 10.1111/j.1365-246x.1991.tb06336.x
Subject(s) - seismogram , seismology , geology , focal mechanism , amplitude , azimuth , seismic wave , refraction , geodesy , geophysics , optics , physics , induced seismicity
SUMMARY The amplitudes of P n ‐waves from New England earthquakes recorded by a regional, short‐period seismic network have been studied to determine the effects of the double‐couple source radiation pattern. Both observed and synthetic seismograms show that P n amplitudes change dramatically with source‐to‐receiver azimuth. These changes are primarily due to the take‐off angles of the seismic rays relative to the nodal planes of the focal mechanism solution. The recordings of a seismic refraction blast show no appreciable change of amplitude with azimuth. The focal mechanism solutions found from inverting the P n amplitudes of several well‐recorded earthquakes are consistent with those obtained from the first‐motion readings. This study has demonstrated that it is possible to calculate focal mechanisms of earthquakes using the polarities and amplitudes of P n ‐waves recorded at a small number of azimuthally distributed local stations.