3-D Peek Inside Mt. Rainier Finds Potential Quake Risk

SEATTLE — The first three-dimensional look inside Mt. Rainier has scientists speculating that there is a potential earthquake hazard in the southeastern corner of the volcanic peak about 60 miles southeast of Seattle.

In 1974, an earthquake of 4.8 magnitude, the largest ever recorded in the national park, was centered on the Ohanapecosh visitors’ center and campground.

“We are definitely observing a systematic change in the geology beneath the surface in the area of the 1974 earthquake,” University of Washington research scientist Seth Moran said Aug. 20. He said it is possible this change represents a buried fault that could be long enough to generate a magnitude 6 earthquake.

Geologists have said for years that the active volcano, the largest in the Cascades, is a potential risk to the communities around it. There is strong geological evidence that massive landslides and mudslides have buried the surrounding area several times over the last 6,000 years.

Researchers have been trying to determine a possible trigger for such a devastating event, and earthquakes may be the answer.

Locating buried active faults is vitally important because earthquakes close to the mountain “pose a much greater threat” to Mt. Rainier than those that are more distant, says Moran, whose research was the basis for his recently completed doctoral dissertation.