Volcano Week
Be Geohazard Aware! Eruptions on volcanoes like Mount Rainier are complicated by the glaciers covering them. During an eruption, glacial ice can melt and mix with rock, ash, and other volcanic materials to form powerful flows of mud and debris. Lahars (volcanic mudflows), post-lahar sedimentation, and flooding can have greater effects on downstream populations than the eruptions themselves, and these hazards can persist for years after the eruption is over. These geohazards can occur during eruptions, after large landslides, even without an active volcanic eruption.
Smaller seasonal debris flows can also be caused by sudden outbursts of glacial water, by intense precipitation, or embankment failure. While detection and warning models are improving, it is important to always be aware of your surroundings. Remember, if you notice a sudden change in water levels, feel the ground rumble, or hear a loud roaring sound, move to higher ground immediately! If you see signs of a debris flow or other geohazard activity, please report it to a ranger.
Mount Rainier is an active volcano with the potential for future eruptions, but eruptions do not happen without warning. The USGS Cascades Volcano Observatory (CVO) carefully monitors Mount Rainier and other Cascade Range volcanoes. Follow the link for Current Alerts for U.S. Volcanos and click the "CVO" tab for Cascade Range volcano updates.
NPS Photo, 2011. A ranger leans against one of the massive boulders left behind from a debris flow along Tahoma Creek. ~kl
