Map shows hazard zone for pyroclastic flows and surges around potential vents in the south moat area of the Long Valley Caldera.

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 km³ of magma and generated pryoclastic flows or surges. The zone is centered along the south moat of the caldera, which is the location of epicenters of many swarms of earthquakes since 1980 and the area of most intense ground movement (deformation). Thus, scientists suggest that future eruptions might occur from this restless zone, and pyroclastic flows and surges could travel as far as 15 km (10 mi) from a new vent. Future pryoclastic flows and surges from a single eruption in the south moat would affect only a part of the total hazard zone shown on the map.