Temporal Variations in Travel Time Residuals of P Waves From Nevada Sources

Recently much attention has been paid to the temporal variation in seismic wave velocities in connection with earthquake prediction problems. This letter reports on an investigation of the temporal variations of travel time residuals of P waves from underground nuclear explosions in Nevada, recorded at Matsushiro (MAT), Kamikineusu (KMU), and some other sensitive seismograph stations. Matsushiro Station is located in the area of the Matsushiro earthquake swarm, the main activity of which occurred in 1966. Kamikineusu Station is located about 20km southwest of the epicenter of the Hidaka earthquake of January 20, 1970 (M=6.7, h=50km). It is very likely that seismic waves from Nevada to KMU pass through the focal region of this earthquake.