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Large lahars (volcanic mudflows) pose substantial threats to people and property downstream from Mount Rainier, Washington. Lahars can occur during an eruption, as happened at Mount St. Helens on May 18, 1980. Lahars can also begin as large landslides that occur without warning, traveling down river channels to densely populated areas downstream.

Jon Major, scientist-in-charge of the USGS Cascades Volcano Observatory, provides an overview of the major volcano hazards in the Cascades, the function and responsibilities of the Cascades Volcano Observatory, and a brief synopsis of what's been going on at Mount Baker, Glacier Peak, Mount Rainier, Mount Adams, Mount St.

The 1980 eruption of Mount St. Helens was monumental in so many different ways. It had a huge impact on the geography of southwestern Washington, ash affected many people, lives were lost, and lessons were learned. The eruption also led to the creation of the USGS Cascades Volcano Observatory in Vancouver, Washington.

The good news is that volcanoes usually change behavior before they erupt, in ways that are detectable by monitoring instruments.

Throughout most of human existence, we haven't known much about how volcanoes work. Because of their immense power, they have terrified and fascinated us, and remain places of great spiritual importance for many people. The lack of knowledge about volcanoes has sometimes resulted in tragic and deadly disasters.

The video describes USGS efforts to improve lahar (mudflow) monitoring at Mount Rainier, an ice-clad volcano in Washington State with potential for dangerous volcanic mudflows. The presentation was given to colleagues in the US and in Ecuador by Andy Lockhart.