The Quaternary deformational history of the East Potrillo Mountains, Dona Ana County, New Mexico
The East Potrillo Mountains are located just north of the U.S.-Mexico border in southwestern Dona Ana County, New Mexico. The structural features exposed in the East Potrillo Mountains formed in response to Laramide and Rio Grande rift deformation and include Tertiary low-angle and high-angle normal faults. Along the east flank of the range are piedmont scarps that indicate continuous movement on the high-angle faults into the late Quaternary. The most dramatic of these is a north-striking fault scarp along the eastern foothills of the East Potrillo Mountains. This geomorphic feature is the result of Rio Grande rift extension. The East Potrillo fault may pose a major seismic hazard to the 2.2 million people that live in the border region. The purpose of this study is to better understand the history of Quaternary deformation along the East Potrillo fault using field and remote sensing observations. Among the objectives of this work are to estimate the average slip rate on the East Potrillo fault and to determine the earthquake recurrence interval. The amount of Quaternary deformation is constrained by measuring displacements of geomorphic surfaces, including alluvial fans and fluvial deposits. Fault scarp age estimates were obtained using morphologic dating techniques applied to surveyed fault scarp profiles. Using three independent morphologic dating techniques, the best estimates for the age of the East Potrillo fault scarps, range from 57 ka to 377 ka. This study estimated the average deformation rate on the East Potrillo fault to be 0.06 mm/yr ±0.002 and the average earthquake recurrence interval is 33.5 kyr ±2.5. Finally, the minimum age of the last major earthquake is still unknown. These results are vital for constraining paleoseismic and tectonic activity as well as seismic hazards in the region.
Cervera, Sarah N, "The Quaternary deformational history of the East Potrillo Mountains, Dona Ana County, New Mexico" (2006). ETD Collection for University of Texas, El Paso. AAI1439489.