Earthquake ‘swarm’ continues southwest of La Pine

Geologists said Friday they will be adding seismometers this weekend as they closely monitor a swarm of dozens of small earthquakes over the past 24 hours in the Ringo Butte area, south of Wickiup Reservoir and about 14 miles southwest of La Pine in northern Klamath County.

“An earthquake swarm fired off” Thursday in the Cascades, on the Crescent Ranger District of the Deschutes National Forest, said an alert e-mailed Friday morning by the U.S. Geological Survey’s Cascades Volcano Observatory in Vancouver, Washington.

The quakes, mostly in the 1-2 magnitude on the Richter scale, have been too small and distant for people to feel, but not to register on seismographs. The largest on Thursday,, around 8:40 p.m., measured 2.5.

By late Friday, more than 50 had been recorded, one even stronger, at 2.9 magnitude shortly before 9 p.m.

After a Saturday lull, another small quake, at 1.4 magnitude, was reported in the area at 8:16 a.m. Sunday, according to the Pacific Northwest Seismic Network. A 1.5 magnitude quake was reported at 6:22 p.m. Sunday and then one measuring 3.0 at 11:11 p.m. Two much smaller ones – 1.0 and .8 – occurred on Monday, it showed.

“Depths are probably all in the upper 10 kilometers, although both the depths and locations have substantial imprecision because the seismic network is sparsely stationed in the area,” the USGS statement said.

The quake swarm in northern Klamath County brings to mind similar recent clusters of dozens, even hundreds of small quakes that occurred in northwest Nevada (southeast of Lakeview) and in the Maupin area.

The USGS geologist found no reports any of the quakes had been felt, “hardly surprising” due to the lesser magnitudes and sparse population in the area.

Indeed, La Pine residents told NewsChannel 21 Friday they had not felt or heard about the quakes.

“Nothing shook, nothing made any noises, nope – not a thing,” a man said.

A woman was surprised by the news: “That’s kind of scary, that there’s been 30. So if there’s a big one coming – that’s sort of scary.”

Most quakes under 3.0 are not felt. Geologists expect the activity will to die down in the next few days, though Mother Earth could have other plans.

“I do want to emphasize that we don’t know the future for something like this,” said USGS geologist David Sherrod. “It is capable of progressing. It’s capable of having earthquakes that are felt, and conceivably earthquakes that are even damaging.”

But in a statement, geologists said, “Cascades Volcano Observatory considers this to be most likely a typical tectonic swarm that will die off in a few days or weeks. Regardless, it is being watched closely.”

“More seismometers will be installed this weekend at the few locations where our existing siting permits and links to the Internet already allow data recovery in real time,” the statement added.

Earthquakes in the area are not unusual, as Central Oregon has its share of fault lines. Experts say it’s unlikely a quake over magnitude over 6 would ever hit Central Oregon, and the “big one” experts warn of is expected to strike a fault off the coast, causing the greatest damage west of the Cascades.

The quakes also have prompted some to ask about any possible relation to the geothermal energy project underway at the Newberry Volcano.

AltaRock Energy’s Newberry EGS (enhanced geothermal systems) project began in 2009 on the western flank of the Newberry Volcano. It uses a process called hydroshearing, injecting cold pressurized water to break through solid rock.

But AltaRock spokesman David Stowe told NewsChannel 21, “We haven’t had any work going on at Newberry for several months.”

Stowe noted a level of “natural seismicity” shows up their seismic monitoring array and sites like the Pacific Northwest Seismic Network. He said the “stimulation” (hot-water injection) has only occurred “for two short periods in 2012 and 2014, and the micro-seismic events we generated were localized in the immediate area of our (equipment) within those two time periods.”

The largest, he said, was 2.4 magnitude at a depth of 7,000 feet but “registered close to zero at the surface.”

Stowe added, “I do think all of the added monitoring at Newberry has revealed more activity that would have gone undetected before.”