Seismicity Monitoring in North-Central New Mexico by the Los Alamos Seismic Network

The first seismic stations of the Los Alamos Seismic Network (LASN) were installed in 1973, as a part of research on monitoring of nuclear testing. The extent of the network rapidly expanded by the late 1970s. By the middle 1980s, spatial coverage of the network was drastically reduced, due to a loss of funding. Since then, however, it has been possible to expand the coverage of the network with additional stations and to slowly upgrade network equipment to match contemporary instrument standards. These improvements will make it possible to keep recording the network’s data and to initiate real-time exchange of data with other institutions to improve earthquake monitoring throughout New Mexico and neighboring states. During more than 40 yr of operation, the network has provided a slow but steady increase in the volume of earthquake seismograms available to study seismicity and tectonics in north-central New Mexico. The current network covers an area from the Valles Caldera on the west, to within the Rio Grande rift on the east. LASN has yielded locations for about 900 earthquakes in north-central New Mexico between 1973 and 2013 (the most recent locations available). Epicenters of these have a complex pattern, with some that can be attributed to the deformation of the rift, though most are spread in areas west of the rift. A lack of seismicity in and near the Valles Caldera reinforces an earlier observation, based on far fewer earthquakes, which first called attention to this paucity of seismicity and attributed it to ductile deformation resulting from elevated crustal temperatures.