Volcanic eruptions millions of years ago shaped the Central Oregon landscape. Massive peaks on the horizon remind residents of the geological past, from Mount Hood, Newberry Volcano and the Three Sisters. But those large mountains only represent less than 1% of all the volcanoes in the Cascade mountain range that have erupted in the past, according to a recently published study from the University of Oregon Department of Earth Sciences.

The study found 2,835 volcanoes in the Cascades, including about 400 in Central Oregon. The Canadian portion of the mountain range was not included in the study.

Many of the identified volcanoes in Central Oregon are hills and buttes found in the Bend and Sisters area and in the Newberry National Volcanic Monument.

“Basically, every small hill surrounding Bend is a volcano, with very few exceptions,” said Leif Karlstrom, a professor in the UO earth sciences department, who co-authored the study.

Karlstrom worked on the study with doctoral student Dan O’Hara and David W. Ramsey, of the U.S. Geological Survey’s Cascades Volcano Observatory in Vancouver, Washington.

Each of the nearly 3,000 volcanoes identified in the study have erupted at least once within the past 2.6 million years. Of those, 231 are active and have erupted within the last 10,000 years.

A few million years of volcanic activity is considered recent for Karlstrom, who said the entire landscape has been active for 40 million years.

“It is a long time, but from the standpoint of a volcano or the Cascade range in general, it’s actually not a very long time,” he said.

Karlstrom points to the lava fields near the Newberry Volcano south of Bend as experiencing relatively recent volcanic activity.

“It looks like a moonscape,” he said. “It looks like fresh lava, but it’s not fresh at all. This erupted thousands of years ago.”

The study does not predict future eruptions, but it will help scientists understand when and where the next

Cascade eruption could take place.

The research team used satellite data to map the entire Cascade range throughout the United States. The information was then compiled in a database, which had never been done before.

“It’s very useful for understanding the Cascades as a whole, over a long time, and it gives us an expectation of what to expect in the future,” Karlstrom said.

Oregon’s landscape has been the focus of several volcanic studies.

The U.S. Geological Survey released a study in 2018 that listed four Oregon volcanoes — Mount Hood, the Three Sisters, Newberry Volcano and Crater Lake — among 18 that pose a “very high threat” of a dangerous eruption.

Karlstrom said people should not be surprised by the threat of volcanoes.

The reason the region has a mountain range and hills for recreation is because of past eruptions.

“We view this as a very active landscape,” he said. “It’s constantly being built, in fact, by magma coming up from the subsurface.”

Rather than one of the large mountains erupting, Karlstrom believes it is more likely the next eruption will sprout from the ground and create a hill of ash and lava.

“It will happen,” he said. “What our study basically says is the Cascades are dominated by these small eruptions.”

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