Mammoth Mountain

Mammoth Mountain straddles the southwest rim of Long Valley Caldera. It is the largest post-caldera volcanic feature in the Long Valley area. Mammoth Mountain was built by a series of approximately 25 separate eruptive episodes between 100,000 and 51,000 years ago.

This hazard zone is based on explosive eruptions from vents located along the chain in the past 10,000 years that are known to have ejected <1 square kilometers (0.25 square miles) of magma and generated pyroclastic flows or surges.