Upgraded seismic equipment installed at Crater Lake National Park two years ago is being credited with having recorded a trio of small earthquakes at the park last Friday.
“We didn’t feel a thing,” park ranger Marsha McCabe said of the quakes.
The largest of the three had a magnitude of .08, according to Seth Moran, a seismologist at the Cascades Volcano Observatory, a U.S. Geological Survey facility based in Vancouver, Wash.
“There’s no way anybody would feel it,” he said, noting reports of the quakes were made because they were the first since a small seismic and geodetic network at Crater Lake was completed in 2011. The network consists of just three seismic stations, making earthquake locations difficult to determine unless events are large enough to be recorded on stations outside of the park.
“With the new network you see new things,” Moran said. “It shows that the volcano is not dead. There are things going on.”
Based on the recorded data, it’s believed the quakes were near the northwestern corner of the crater rim at a depth of about three to six miles.
Before Friday’s recordings, Moran said the most recent earthquakes recorded at the park were events with magnitudes of 2.3, 2.6, and 2.4 that occurred near Rim Village within 20 minutes of each other on the afternoon of Dec. 29, 1994. The largest two events were felt by people at the park, according to the website.
“The bottom line is the Crater Lake area is not necessarily dead,” Moran said. “We’ve waited 7,000 years since the last eruption. It could be quite a while before another one. But it is worth paying attention to on a human scale.”
Crater Lake was formed when Mount Mazama exploded about 7,700 years ago.
Moran said seismic data collected at Crater Lake will be used to determine “what is normal.” While the reports from Crater Lake were the first in two years since the new equipment was installed, far more frequent quake reports are recorded at, for example, Newberry Crater, with about one a month, and Mount St. Helens, with one or two a day.