Time-lapse monitoring of velocity changes in Utah

Abstract

The Eastern part of the Basin and Range, extending to the Wasatch fault region, is an actively deforming region characterized by varieties of extensive features and prominent seismicity along the intermountain seismic belt. The present-day deformation of the intermountain seismic belt and the eastern Basin and Range province motivates an interest in continuous monitoring of the region. In this study we monitor time-lapse velocity changes within Utah and eastern Nevada using coda waves generated by repeatable explosions. This monitoring characterizes velocity changes within the region from June to September of 2007. We observe, both temporally and spatially, variable velocity changes within the monitored region, with a maximum path average velocity change of 0.2%. This suggests a significant change in the velocity within the region given the short monitoring duration. Correlation of the temporal variation of the average velocity change with strains derived from GPS-detrended displacements suggests that the velocity change might be driven by the broad deformation within the monitored region. Key PointsRepeating seismic experiments for monitoring velocity changes across UtahThere is an observed and clear velocity change over a time period of 4 monthsVelocity changes might be due to the crustal deformation in the Basin and Range