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Our deadly volcanoes

A killer volcano that erupted on an island near New Zealand is a stark reminder that Jackson County is ringed by mountains that could blow their tops and send a cloud of deadly ash over the region.

“Every 50 years or so there is a large eruptive event,” said Althea Rizzo, coordinator for the Oregon Office of the Emergency Management Geologic Hazards Awareness Program. “They happen more often than people think they do.”

On Monday, a volcano erupted suddenly on remote White Island, also called Whakaari, a popular tourist destination in New Zealand. Five people died, eight are missing and 34 survived, of which 31 are receiving treatment, many for severe burns.

White Island and the Cascade range in Oregon share something in common. They’re both located on the Pacific “ring of fire,” which is both an earthquake- and volcano-prone area at or near the land masses on either side of the ocean.

The Cascades are well known for volcanic activity, with the last major eruption being May 18, 1980, on Mount St. Helens.

The U.S. Geologic Service lists four volcanoes in Oregon that are a “very high threat.”

Mount Hood near Portland is on the list, and geologists predict a potential eruption could generate a massive slug of concrete-like material that would flow all the way to the Columbia River. Mount Hood often vents gas and steam, indicating it is geologically active.

Crater Lake also has a high potential for eruption, according to the USGS.

Crater Lake was formed when Mount Mazama, roughly as tall as Mount Shasta, blew its top 7,700 years ago. It’s at the top of the U.S. Geological Survey’s list of mountains that could blow at any time.

Less well known is Newberry Volcano, which has two lakes — Paulina Lake and East Lake — formed in calderas just south of Bend, which last erupted 1,300 years ago.

The Three Sisters are also on the list, last erupting about 1,500 years ago.

The USGS ranked five mountains in the U.S. on its most dangerous list. At the very top is Hawaii’s Kilauea, which is very active. The others are Mount St. Helens and Mount Rainier in Washington, Alaska’s Redoubt Volcano, and California’s Mount Shasta, which can be seen from numerous vantage points in Southern Oregon.

If Mount Shasta blew, it could be as devastating as the volcano that turned Mount Mazama into Crater Lake, officials say. Mount Mazama was likely as tall as Mount Shasta.

Mount Lassen, east of Redding, last blew up in 1915 and sent ash drifting almost 300 miles away.

Mount St. Helens erupted May 18, 1980, and 57 people died from asphyxiation after 549 million tons of ash rained down on the Pacific Northwest.

Rizzo said ash from Mount St. Helens fell Pullman, Washington, some 300 miles away, where she was living at the time.

The most active volcano in the Cascades, Mount St. Helens last erupted July 10, 2008, though it was a much smaller event than in 1980.

According to the USGS, the eruption caused $1 billion in damages. Lahars, concrete-like volcanic flows of ash and mud that block streams and rivers, damaged 27 bridges and 200 homes.

While volcanoes push out a lot of toxic material, the mountains in Oregon are generally located a good distance away from heavily populated areas, though residents living nearby may need to evacuate.

Geologists often get warning signs that a mountain is about to blow, but Rizzo said there isn’t sufficient detection equipment around most of the peaks in Oregon.

“We don’t have as good a monitoring system as the scientists would like,” she said.

Only Mount Hood has enough equipment to provide sufficient data for geologists who keep track of volcanic activity, Rizzo said.

Other volcanoes, including Crater Lake, have less, but there are earthquake monitoring stations located around the lake.

Rizzo said there is more concern about the bigger mountains blowing because they can eject the most debris, potentially causing widespread damage.

In an eruption, the ash cloud can cause asphyxiation or potentially lead to other health problems.

“You certainly don’t want to breathe it,” she said.

In addition to potentially causing silicosis in people, the ash cloud can damage machinery and electronics, as well as killing wildlife.

Geologists typically get warnings that a mountain is about to blow, allowing time to flee a particular area.

Similar to preparing for an earthquake, residents are encouraged to have an emergency kit that includes a respiratory mask, goggles, medications, spare contact lenses and glasses, and also prepare to tape and seal your house to prevent ash from coming in.

If an evacuation is declared, have a family disaster plan prepared so that you can find a way to contact them later in case you get separated.

Reach reporter Damian Mann at 541-776-4476 or dmann@rosebudmedia.com. Follow him on www.twitter.com/reporterdm.

In this April 1980 file photo, Mount St. Helens spews smoke, soot and ash into the sky in Washington state following a major eruption on May 18, 1980. AP Photo/Jack Smith