Lithospheric Profiles in the Southwestern U.S. Using Nevada Test Sites Sources.

Abstract : The objective of this grant is to conduct a variety of seismic investigations in the southwestern U.S. and to use the results to determine lithospheric structure and seismic wave propagation in the region. The 'Minor Uncle' explosion at the White Sands Missile Range (WSMR) was recorded in June, 1993 and the resultant data has been interpreted in the effort to establish a lithospheric transect between the Nevada Test Site (NTS) and the WSMR. Data sets have been obtained for the tomographic study of the Mojave desert area and the initial modeling has begun to form the basis for tomographic inversions. Valuable experience with tomographic techniques has been gained by applying them to Pg phase data from the 1989 PACE (Pacific to Arizona Crustal Experiment) experience. An excellent picture of upper crustal structure in the PACE area is emerging from combining the tomographic results, Pg phase inversions, and analysis of gravity anomalies. Analysis of the eastern part of the NTS-WSMR profile reveals that the deep lithospheric effects of the Rio Grande rift are more pronounced than previously predicted and the effects extend about 100 km beyond the physiographic boundaries of the rift. An important framework has been established for the upcoming refraction experiment in the Sierra Nevada region.