Baja California, Mexico
32.418 N, 115.305 W
summit elevation 223 m
Cerro Prieto volcano is located at the northern end of the gulf of California, 177 km SE of San Diego, and 30 km from the US border. The volcano consists of a low lava dome.
Cerro Prieto geothermal field is located at the volcano. The system is a large high-temperature (280-350ºC), liquid dominated field, contained in sedimentary rocks. The geothermal field began producing electricity in 1973. Cerro Prieto field is estimated to maintain its current capacity until the year 2030.
The volcano is located in a transition between the East Pacific Rise and the strike-slip San Andreas fault system. It is one of the few areas where on-land spreading is observed.
The heat source for the volcano is thought to be a magma body at a depth of 5–6 km. There is a significant correlation between increases of sustained fluid extraction at the field and earthquakes, with delays of about 1 yr.
An earthquake swarm occurred under Cerro Prieto volcano in Mexico between 8-11 February 2008. The seismic swarm began on 8 February 2008 at 11:12 pm (Pacific Time) with a magnitude 5.1 earthquake. A second magnitude 5.1 earthquake occurred on 11 February 2008 at 10:29 am (Pacific Time) about 4 miles further south. Both events, were shallow, at a depth of less than 3 miles. Sixteen earthquakes greater than magnitude 3 were recorded over 2.5 days. The two magnitude 5 earthquakes were tectonic, consistent with activity on the Cerro Prieto fault.
The last eruption at the volcano is unknown, but may be within the past 10,000 years.