Coso Volcanic Field


Although the youngest eruption was dated at about 40,000 years the robust geothermal system and evidence of a magma reservoir underneath Coso Volcanic Field suggests that future eruptions are likely.

Earthquakes would precede any eruption.

Weeks to months of heightened earthquake activity and ground deformation would probably precede a future eruption. Since the region is geothermally active, an eruption would likely start with a series of low-level steam blasts.

Two types of eruptions may occur at Coso volcanic field.

Very energetic explosions of ash and tephra may occur if a more silicic magma (such as rhyolite) is tapped. These eruptions may send a vertical column of volcanic ash several thousand feet in the air. Ash from the column may travel tens of kilometers downwind. The explosive phase of such an eruption might be succeeded by slow, thick effusion of lava that would pile up around the vent creating a steep-sided lava dome.

Alternatively, an eruption with incandescent fountains of basalt lava rising a few to hundreds of meters (tens to hundreds of feet) in the air is also possible. A hill of volcanic cinder would form around the vent, and slow-moving lava flows would spread over the landscape impacting areas at most a few kilometers away. Future eruptions are more likely in the western half of the Coso Volcanic Field.