Hazards

Mount Hood is an active volcano close to rapidly growing communities, recreation areas, and major transportation routes and therefore imposes heightened risk.

Lahars can be generated by hot volcanic flows that melt snow and ice or by landslides (debris avalanches) from weakened rock forming the steep upper flanks of the volcano.

Lava flow hazards are restricted to the flanks of Mount Hood. Lava dome hazards can trigger far-travelled hazardous events.

Mount Hood has typically not produced thick, extensive deposits of tephra, but relatively modest amounts of tephra were produced during past lava-flow and lava-dome eruptions.

When Mount Hood erupts again, it will severely affect areas on its flanks as well as locations far downstream in the major river valleys that head on the volcano.

Dome-collapse pyroclastic flows, tephra fall, and lahars are common on Mount Hood and have occurred during all eruptive periods of the past 30,000 years. They are very likely to occur in future eruptions.

Excess sedimentation occurs in rivers and streams that head on volcanoes when huge volumes of volcanic sediment are washed far downstream by lahars and muddy floods.