A STUDY OF ONE PRECARIOUSLY BALANCED ROCK IN THE COYOTE MOUNTAINS IN RELATIONSHIP TO THE APRIL, 4TH, 2010 EL MAJOR-CUCAPAS MW 7.2 EARTHQUAKE USING DIGITAL ORTHO-QUADRANGLES AND UAVSAR INTERFEROGRAMS

In the southwest of USA, Jim Brume and others have been studying Precarious Balanced Rocks (PBR) and their relationship to seismic events. In the Coyote Mountains a PBR failed during(?) the April, 4^th, 2010 El Major-Cucapas M_w 7.2 Earthquake. Two problems became evident while studying this PBR: 1) knowing which rocks are precariously balanced and; 2) the time when this particular PBR failed. Using the July 1, 2010 dated UAVSAR interferograms, provided by Jerry Treiman, help with the study of this particular PBR and other types of seismic failures in the Coyote Mountains. The PBR failed sometime between twenty and 66 days after the El Major-Cucapas Earthquake. The block did not fail during the El Major-Cucapas M_w 7.2 Earthquake, but the earthquake may have contributed to the instability of the block which eventually lead to the PBR failure. The June 15, 2010, M_w5.7 aftershock(?) that was north of the international border and closer to the PBR, probably triggered the failure of the PBR. Using UAVSAR interferograms after a seismic event can help in finding unrecognized PBR that have failed.