Skip to main content
U.S. flag

An official website of the United States government

Mount Adams

Find U.S. Volcano

Mount Adams is the largest active volcano in Washington State and among the largest in the Cascades.

Quick Facts

Location: Washington, Yakama Nations Reserve and Skamania/Yakima Counties

Latitude: 46.206° N

Longitude: 121.49° W

Elevation: 3,742 (m) 12,277 (f)

Volcano type: Stratovolcano

Composition: Basalt to Andesite

Most recent eruption: 3,800 years ago

Threat Potential: High*

*based on the National Volcano Early Warning System

Summary

Mount Adams, Washington as seen from Mount St. Helens (west). Tree...
Mount Adams, Washington as seen from Mount St. Helens (west). Trees are covered in frost in the foreground.

The volcano has produced a larger volume (about 300 km3 or 70 mi3) of eruptive material during the past million years than any other Cascade stratovolcano except Mount Shasta (about 350 km3 or 85 mi3). Mount Adams lies in the middle of the Mount Adams volcanic field—a 1,250 km2 (about 500 mi2) area comprising at least 120, mostly basaltic volcanoes that form spatter and scoria cones, shield volcanoes, and some extensive lava flows. The volcanic field has been active for at least the past one million years. Mount Adams was active from about 520,000 to about 1,000 years ago and has erupted mostly andesite. Eruptions have occurred from ten vents since the last period of glaciation about 15,000 years ago. Approximately 6,000 and 300 years ago, debris avalanches from the southwest face of Mount Adams generated clay-rich lahars that swept more than 30 km2 (11 mi2) south of the volcano along the White Salmon River. The summit of Mount Adams contains a large section of unstable altered rock that can spawn future debris avalanches and lahars.

News

Monitoring stations detect small magnitude earthquakes at Mount Adams (September 2024)

Monitoring stations detect small magnitude earthquakes at Mount Adams (September 2024)

Status of (mostly) Washington's Volcanoes: Report to Emergency Managers 2020-2021

Status of (mostly) Washington's Volcanoes: Report to Emergency Managers 2020-2021

Which U.S. volcanoes pose a threat?

Which U.S. volcanoes pose a threat?

Publications

2018 update to the U.S. Geological Survey national volcanic threat assessment

When erupting, all volcanoes pose a degree of risk to people and infrastructure, however, the risks are not equivalent from one volcano to another because of differences in eruptive style and geographic location. Assessing the relative threats posed by U.S. volcanoes identifies which volcanoes warrant the greatest risk-mitigation efforts by the U.S. Geological Survey and its partners. This update

Authors
John W. Ewert, Angela K. Diefenbach, David W. Ramsey

Science

Pyroclastic Flows at Mount Adams

Pyroclastic flows are a rare occurrence at Mount Adams, but it is possible for them to occur.
link

Pyroclastic Flows at Mount Adams

Pyroclastic flows are a rare occurrence at Mount Adams, but it is possible for them to occur.
Learn More

Lava Flow Hazards at Mount Adams

Lava flows are the most likely type of future eruptive event, but they do not pose as much of a hazard as landslides or lahars because they move slowly (a person can out run a lava flow) with relatively predictable flow pathways
link

Lava Flow Hazards at Mount Adams

Lava flows are the most likely type of future eruptive event, but they do not pose as much of a hazard as landslides or lahars because they move slowly (a person can out run a lava flow) with relatively predictable flow pathways
Learn More

Earthquake Monitoring at Mount Adams

The Pacific Northwest Seismic Network (PNSN) and CVO monitor seismicity at Mount Adams via a single nearby station (ASR, located about 10 km (6 mi) from the summit) and the broader regional PNSN network.
link

Earthquake Monitoring at Mount Adams

The Pacific Northwest Seismic Network (PNSN) and CVO monitor seismicity at Mount Adams via a single nearby station (ASR, located about 10 km (6 mi) from the summit) and the broader regional PNSN network.
Learn More
Was this page helpful?