SEISMICITY OF THE ROCKY MOUNTAINS AND RIO GRANDE RIFT FROM THE USARRAY AND CREST TEMPORARY SEISMIC NETWORKS, 2008-2010 (Invited Presentation)

We develop a catalog of small magnitude seismicity across Colorado and New Mexico from the Earthscope USArray Transportable Array/CREST seismic networks from 2008-2010 to characterize active deformation in the Rio Grande rift. We recorded over 800 earthquakes in the Rio Grande Rift region, not including induced earthquakes and mine blasts, and find that the rift is actively deforming in three distinct regions. In the northern rift, Neogene faults in northern Colorado are seismically active in the North Park basin and northwestern Colorado. The central rift is the most seismically active portion of the rift, and seismicity is spatially correlated with volcanic vents, dikes, and Quaternary faults on the western Jemez Lineament. The seismicity in the central rift is focused on the transition zone between the Colorado Plateau and the Rio Grande rift, indicating a higher rate of deformation along the boundary. Seismicity in the Great Plains is absent in northeast Colorado, the eastern Jemez Lineament, and southeast New Mexico, which may be strong relative to the seismically active portion of the Great Plains, a seismic belt with relatively high moment release that trends northeast from Albuquerque, New Mexico to the Texas Panhandle. The southern rift is characterized by diffuse seismicity, a north-south striking trend of higher magnitude earthquakes on the Arizona-New Mexico border, and continuing rift seismicity into Texas and Mexico, indicating that the rift extends well past the New Mexico-Mexico border. During this time period, clusters of seismicity and moderate magnitude earthquakes characterize deformation in a low-strain rate extensional environment.