Volcanos are considered active if they are currently erupting or have erupted within the last 10,000 years. A dormant volcano is not currently erupting but is expected to erupt again in the future. An extinct volcano has not erupted within the past 10,000 years and is not expected to erupt again in the near geologic future.

Related Hazards

• Pyroclastic flows (avalanches of hot ash, rock, and gas)
• Lava flows (molten rock)
• Lahars (mudflows)
• Tephra (solid material blown into the atmosphere, large rock fragments and “volcanic bombs”)
• Hazardous gases, such as sulfur dioxide

Precautions

• If you live near an active volcano, consult lava flow path maps when deciding where to purchase or build a home. 
• Have an evacuation plan and disaster supply kit ready, including goggles and disposable breathing masks.
• Prepare a family emergency communication plan.

What to Do When an Eruption Occurs

• Wear a dust mask or wet handkerchief to filter out ash.
• Close all building windows and doors to keep ash out.
• Follow evacuation orders and leave the area immediately to avoid flying debris, gases, and lava flows.
• Do not cross streams or bridges if a mudflow is approaching. Look upstream.
• Seek higher ground, as mud and debris will accumulate in low-lying areas.

Resources

Smithsonian Global Volcanism Program

USGS Volcano Hazards Program

USGS Hawaiian Volcano Observatory