"The Coso volcanic field is located about 160 km (100 mi) northeast of Bakersfield, California, mainly within the boundary of the Naval Air Weapons Station, China Lake. It covers approximately 400 km2(roughly 150 mi2) and is home to one of the largest producers of geothermal power in the U.S., with an output sufficient to supply the needs of 270,000 homes. The geothermal resource fuels the many hot springs, steam vents, and boiling mud pots near the center of the Coso Volcanic Field. About 40 eruptions in the last quarter million years produced a field of steep-sided lava domes, red hills of volcanic cinder, and rough-surfaced lava flows. The most recent eruption occurred about 40,000 years ago forming the Volcano Peak basaltic cinder cone and lava flow. Some geological landform relationships suggest that the youngest lava dome may have formed within the past 12,000 years, but this young activity has not been confirmed via dating methods. Geophysical and geochemical studies detect a zone of partially molten rock (magma) underlying the center of the Coso Volcanic Field. Small to moderate earthquakes, some due to the geothermal resource are common. The U.S. Navy monitors earthquake and geothermal activity within the Coso Volcanic Field."