Introduction - From the first data recorded in the fall of 1973 to now, the Los Alamos Seismograph Network (LASN) has operated for almost 30 years. During that time LASN data have been used to locate more than 2,500 earthquakes in north-central New Mexico.
The network was installed to aid in seismic verification research as well as to monitor quakes for Los Alamos National Laboratory. LASN once included as many as 22 stations spread over a geographic area of 150 km (N-S) by 350 km (E-W), but was downsized in the mid 1980s. Currently, 9 earthquake monitoring stations are operated, all within or near Los Alamos National Laboratory. Seven of these are short-period, radio-telemetered stations with 1-Hz geophones. The other two stations have digital broadband seismometers with spread-spectrum digital RF telemetry. All stations have 3-component (vertical, north-south and east-west) sensors. In addition, five forensic strong-motion accelerometers (SMA) and one vertical SMA array are operated at LANL facilities.
More than 2,000 earthquakes were detected and located throughout northern New Mexico during the first 11 years of the network's operation (1973 to 1984). With the subsequent "down-sizing" of the network, about 1-2 nearby earthquakes a month are detected and located. We consider earthquakes to be nearby if the time between their P and S wave arrivals is about 20 seconds or less. That corresponds roughly to about 150-160 km distance from the network.
Los Alamos Seismic Network's (LASN's) Seismic Stations - The first plot above shows topography of north-central New Mexico. The Jemez Mountains are in the middle, and within them, the Valles Caldera is the circular feature. The Sangre de Cristo Mountains are at the right. Other features are: LASN stations (blue triangles), faults (black lines), rivers (blue lines), major roads (green lines), and selected towns (green). The second plot shows the Los Alamos area and the current LASN station locations. The legend indicates the instrumentation of each station.
LASN Station Info
LASN Station Photos