Signal Detection and Earthquake Catalogue Development Using a Short-term, Over 800-station, Mixed-mode Seismic Array Deployed Above the Socorro Magma Body, NM

Thursday, 17 December 2015
Poster Hall (Moscone South)
Susan L Bilek1, Brandon Schmandt2, Steve M Hansen2, Lindsay Lowe Worthington2 and Richard C Aster3, (1)New Mexico Tech, Socorro, NM, United States, (2)University of New Mexico Main Campus, Albuquerque, NM, United States, (3)Colorado State University, Geosciences Department, Fort Collins, CO, United States
Magma movement and emplacement within the crust is an important aspect to understanding crustal formation and deformation. The 19-km deep Socorro Magma Body, the second largest mid-crustal continental magma body known worldwide, produces measurable crustal deformation and seismicity within the Rio Grande Rift region in central New Mexico. There have been a variety of studies to estimate the location and size of this feature as well as possible changes related to magma or fluid migration. The extent of the feature has been previously estimated by observation of reflected phases arising from earthquakes located above the feature recorded by a sparse local seismic network. To improve our understanding of the spatial extent of the Socorro Magma Body, we deployed a mixed mode seismic array for 2 weeks over the northern portion of the magma body consisting of 7 3-component broadband seismometers and over 800 Fairfield vertical-component autonomous node seismographs with integral 10 Hz seismometers. This array will allow for us to improve our estimates of spatial extent of the body and possible heterogeneities resulting from fluid or magma migration at shallower depths. Here we focus on initial steps to analyze this large volume of data, in conjunction with other local and regional seismic stations, to determine a local and teleseismic earthquake catalog during the deployment time period. These earthquakes will then be used to probe the structure of the Socorro Magma Body and its surroundings. We employ multiple strategies for building this catalog, including standard amplitude-based detection tools with the broadband data, triggering algorithms with the node data, and back-projection of the node data over limited sections of the array. Initial results suggest a number of previously undetected earthquakes located beneath the array, as well as regional events from an earthquake sequence in Arizona.