Would a local erution be similar to the Mount St. Helens eruption?
It is very unlikely. Most of the damage caused by the Mount St. Helens was due to a lateral eruption that blew the entire north side of the mountain away. Eruptions in the Long Valley area in the last 4,000 years have been vertical eruptions from isolated vents. Is Mammoth an active volcano? No. It is a dormant (“sleeping”) valcano. • Is there a higher risk of damage from geological activity in this area than elsewhere in California? No. In fact, other areas of California face a somewhat higher risk because of many active faults and the relative high frequency of moderate to large earthquakes. Are small earthquakes considered normal activity for this region? Small earthquakes are common in this area and do not present an immediate threat. What is the largest recorded earthquake in the Mammoth area? In May of 1980 there were four magnitude 6 earthquakes. Is the area monitored for geologic activity? The area surrounding the Long Valley Caldera is one of the closest monitored regions in t
