Be Geohazard Aware!

Recent research has improved our understanding of Mount Rainier, an active volcano. Active steam vents, periodic earth tremors, and reported historical eruptions provide evidence that Mount Rainier is sleeping, not dead. Seismic monitoring stations around the mountain should provide days or weeks of advance warning of impending eruptions. However, other geologic hazards like debris flows, glacial outburst floods, and rockfall can occur with little warning.

Detailed geohazard information is available at park visitor centers and from scientists at the USGS Cascades Volcano Observatory.

The more time you spend in an area where there are geologic hazards, the greater the chances that you could be involved in a geohazard event. While the chances of observing a geologic event are relatively low, you must decide if you will assume the personal risk of visiting these potentially dangerous locations. When you arrive in the park, be sure to review posted geologic hazard, evacuation, and escape information. Longmire, Carbon, and the campgrounds at Cougar Rock, Ohanapecosh, and White River are all vulnerable to geologic hazards. Many trails pass through geohazard areas. Remember, ANY glacially-sourced river in the park is at risk of a debris flow.

Rising water level, shaking ground and a rumbling noise may signal a debris flow or lahar. If you are near a river and notice:

• A rapid rise in water level
• Feel a prolonged shaking of the ground
• Hear a roaring sound coming from up valley (often described as the sound made by a fast–moving freight train)

Then move quickly to higher ground! A location 160 feet (50 m) or more above river level should be safe.

Geohazard Warning Sirens

Geohazard sirens are located at high visitor concentration locations along the Nisqually river including Cougar Rock Campground, Longmire, and Nisqually Entrance. If you hear the siren during your visit, head uphill, away from rivers.

Geohazards & Trails: Tahoma Creek Trail

The former Tahoma Creek Trail has a long history of hazardous and life-threatening conditions. In the late 1980s, a very large debris flow destroyed several sections of the trail and a large section of the Westside Road, leaving visitors, staff, and vehicles stranded. Since that time the Westside Road has been closed to public vehicle access at Dry Creek and Tahoma Creek Trail was no longer maintained.

Tahoma Creek continues to have floods and debris flow events, with around 35 debris flows and glacial outburst floods recorded from 1967 to 2023 (a 2015 debris flow was filmed by visitors hiking the Westside Road). Each event has impacted the road and degraded existing sections of the trail, making it difficult and sometimes impossible to navigate Tahoma Creek Trail.

Hiking Tahoma Creek Trail is not recommended. Debris flows contain large volumes of water, mud, boulders, trees, and anything else picked up along the way. They almost always occur suddenly and move rapidly downstream. If you are in the debris flow corridor you may have no avenue of escape.

Tahoma Creek Trail is an example of a trail particularly hard hit by geohazard events, but it is not the only trail in the park at risk of floods and debris flows. Most trails in the park pass through geohazard zones. Remember, if you notice a change - either a sudden drop or rise - in water levels, feel the ground rumble, or hear a loud roaring sound, move to higher ground immediately!