Every once in a while the smell of rotten eggs wafting over from Devil's Kitchen serves as a reminder that Mount Hood is a volcano that has erupted before, and will erupt again. What will happen next time it erupts? And how much warning will there be?

A new study by geologists Adam Kent of Oregon State University and Kari Cooper of UC-Davis finds that the next Mount Hood eruption could happen fairly quickly, but it will likely be more of an oozing overflow than a dramatic explosion, and it will be fairly easy to predict in advance.

The study was published in the journal Nature with the title "Rapid remobilization of magmatic crystals kept in cold storage."

As the title suggests, Kent and Cooper found a thick layer of cool magma about three miles under Mount Hood that has been largely immobile for thousands of years, in a form of cold storage expected to persist so long as the temperature stays below 750 degrees Celsius.

If very hot magma rises from deep below and mixes with that layer of cooler magma, it could liquefy and mobilize fairly quickly, within a month or two, potentially leading to an eruption.

That is what happened to cause Mount Hood's two most recent eruptions, 220 years ago and approximately 1,500 years ago.

The good news is that the thick layer of cool magma under the mountain has constrained the violence of past eruptions and will likely temper future eruptions as well.

“What happens when they mix is what happens when you squeeze a tube of toothpaste in the middle,” said Kent, a professor in OSU’s College of Earth, Ocean, and Atmospheric Sciences. “A big glob kind of plops out the top, but in the case of Mount Hood – it doesn’t blow the mountain to pieces.”

Kent says scientists should be able to detect when the magma is starting to liquefy and mobilize by monitoring gases, using seismic waves and using GPS to study ground deformation below the mountain.

Here is a YouTube video from UC Davis with Kari Cooper explaining the findings: