G141 REVIEW:  VOLCANIC HAZARDS

Ash Fall

• Covers all topography
• Distances to 100+ km
• Wind dispersal of ash
• Coarse tephra close to vent

Pyroclastic Flow

• Affects low-lying areas
• Distances to ~20 km
• Affects areas close to vent

Lava Flow

• Vent area + low-lying areas
• Distances to 10 km (silicic magmas)
• Greater distances for more fluid magmas

Lahar

• Confined to river valleys
• Distances to 70+ km
• Source area of ash, poorly consolidated rock

Landslide/Avalanche

• High-relief areas near volcano
• Ice cap

Tsunami

• Low-lying coastal areas near volcano
• Source area:  submarine eruptions/landslides

Gas

• Areas close to summit vent
• Low-lying areas near lakes

Others

• Lateral blast
• Flooding/logjams
• Wildfires