New Mexico experiences moderate levels of earthquake activity, primarily because of extension along the Rio Grande rift, a large, fault-bounded geologic valley that runs north-south through the center of the state. Geologic studies of ancient earthquakes (known as paleoseismology) show that earthquakes as large as magnitude 6.5 (M6.5) or larger have occurred along the Rio Grande rift within the past several thousand years, and smaller earthquakes of M2.5–3.5 take place in various parts of the state every year. The highest concentration of naturally occurring earthquakes is near the Socorro Magma Body, where a M6.2 earthquake occurred on November 15, 1906. This was the largest historic earthquake in New Mexico and it damaged several buildings in Socorro.
Although there is a long history of naturally occurring seismicity in New Mexico, increasing numbers of earthquakes have been observed over the past several years in some parts of the state that did not experience much seismic activity in the past. These earthquakes are believed to be associated with human activities rather than tectonic or magmatic forces, and are referred to by the term “induced seismicity.” Even though most induced earthquakes are too small to be felt by humans, or to cause any damage, in some places around the world induced earthquakes have damaged buildings and infrastructure. This has led to the installation of new monitoring stations in many areas to better understand the causes of induced seismicity and to minimize its risk.