Papers Published

1. Leary, P.C. and Malin, P.E., Millisecond accurate monitoring of seismic travel times over 13- and 18-kilometer baselines, J. Geophys. Res. (USA), vol. 87 no. B8 (1982), pp. 6919 - 30 .
   (last updated on 2007/04/09)

   Abstract:
   Using a repeatable airgun source the travel times of several seismic phases were monitored along 13- and 18-km baselines from Bouquet Reservoir to boreholes on the San Andreas fault near Palmdale, California. The first arriving phases refract at a depth of 2-3 km, while one later arrival is possibly a reflection from 10 km. The majority of some 200 travel time determinations for the most prominent phases were made between August 1979 and March 1980. There exists ample geodetic and other evidence for significant strain changes during this period. The authors performed a study of the depth dependence of seismic velocity strain sensitivity. It was found that 1 bar of overpressure at 500 m can vary the P velocity by 0.1%, while 1 bar at 2000 m will vary the velocity by only 0.01%. Applying the O'Connell-Budiansky physical model for cracked rock to the velocity depth profiles, it is possible to further characterize the local crust as having a high crack density, a mobile fluid component, and an average crack aspect ratio of 2.5×10^-3

   Keywords:
   seismic waves;seismology;tectonics;