The epicenter of the Texas earthquake of August 16, 1931 has been relocated instrumentally much closer to the area of maximum seismic intensities near Valentine, Texas. Regional and local teleseismic P-wave arrival time anomalies observed for the nearby Gnome underground nuclear explosion of 1961 are used to determine station corrections and thus to locate the new epicenter at 30.69°N, 104.57°W. This epicenter lies in a diffuse, elongated area of seismicity detected by a local seismograph network installed in 1976. The present seismic activity indicates a fault striking N50°W. A new analysis of the first-motion data reported in 1931 suggests that the Texas earthquake occurred on a strike-slip fault with right-lateral displacement and with the tension axis oriented S74°W. Several estimates of magnitude (mb) based on intensity data range from 5.6 to 6.4.

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