Premonitory Variations in S-Wave Velocity Anisotropy before Earthquakes in Nevada

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Science  14 Dec 1973:
Vol. 182, Issue 4117, pp. 1129-1132
DOI: 10.1126/science.182.4117.1129


Application of nonhydrostatic stress to rock induces velocity anisotropy, causing the S wave to split into two components traveling with somewhat different velocities. Large premonitory changes in the extent of S-wave splitting have been observed for two earthquakes in Nevada. Observations of the difference between the two S-wave velocities may provide a simple method for pedicting earthquakes.