Several hazards will likely accompany a future eruption of Lassen volcano. Heightened seismicity and ground deformation will probably precede the next eruption. Most likely is an effusive eruption with incandescent lava fountains rising a few to hundreds of meters (tens to hundreds of feet) in the air. A mound of volcanic cinder would gradually build around the vent and slow-moving lava flows could impact areas a few kilometers away. Future explosive eruptions, similar to Lassen Peak or the larger Chaos Crags, are also possible.
The areas of highest hazard in the region of Lassen Volcanic National Park are those that could potentially be affected by pyroclastic flows and mudflows (click the map to the left to see a larger image). These areas are those in the immediate vicinity and downhill from likely eruption sites. Fallout of ash will affect areas downwind at the time of an eruption. Within the hazard zones, relative hazard is gradational, decreasing away from the location of potential vents.