Mount Adams

Oct. 15, 2024

Mount Adams, Washington's largest volcano, has recently shown a surge in seismic activity after remaining largely dormant for thousands of years.

About Mount Adams:

  • It is a stratovolcano located in Washington State, United States.
  • At 12,277 feet (3,742 meters) high and 18 miles (29 kilometers) wide, Mount Adams is the largest active volcano in Washington, surpassing Mount Rainier — the state's highest peak — by volume.
  • Mount Adams lies in the middle of the Mount Adams volcanic field—a 1,250 sq. km area comprising at least 120, mostly basaltic volcanoes that form spatter and scoria cones, shield volcanoes, and some extensive lava flows.
  • Mount Adams supports over 10 active glaciers that provide water to the forests, streams, and meadows below.
  • The most recent eruption at the site occurred sometime between 3,800 and 7,600 years ago when humanity was still in the Stone Age.

What is a Stratovolcano?

  • Stratovolcanoes (also known as composite volcanoes) are tall, steep, and cone-shaped types of volcanoes.
  • Unlike flat shield volcanoes, they have higher peaks.
  • They are built of successive layers of ash and lava.
  • The magma (molten rock) within the volcano is viscous and often contains trapped gas, causing explosive eruptions. 
  • Stratovolcanoes occur at the margins of tectonic plates, large sections of Earth's crust that move together. 
    • The continental plates, composed of less dense material, override the oceanic plates.
    • Magma generated from the subducting plate rises and squeezes into cracks, eventually reaching the surface in a volcanic eruption.
  • They comprise the largest percentage (~60%) ofthe Earth's individual volcanoes.
  • Approximately 85% of stratovolcanoes are located around the Pacific Ocean, forming what is called the “Ring of Fire.”