The Montenegro,Yugoslavia, earthquake of April 15, 1979: source orientation and strength

Long-period teleseismic P, S and Rayleigh waves and geologic considerations indicate that the Montenegro earthquake involved thrust faulting on a plane striking nearly parallel to the Adriatic coast and dipping ca. 15° toward the Yugoslav mainland. There is some support from modeling of body waves recorded on long-period WWSSN instruments for a focal depth of 22 km, but the possibility of a multiple source and the difficulty of matching some of the detailed characteristics of the P- and S-wave forms reduce our confidence in the determination of the depth. Fortunately, the source orientation and moment of the event are not sensitive functions of the depth. The long-period (256 s) moment was 4.6 × 10¹⁹ Nm (4.6 × 10²⁶ dyne-cm). The moment obtained by fitting the first cycle of P and S waves recorded on WWSSN long-period instruments is about four times smaller. This increase of moment with period is consistent with spectral estimates of the moment from SH waves recorded at SRO and ASRO stations.