A report published this week in Nature Geoscience by geologists from Oregon State University and the University of California at Davis, in work supported by the National Science Foundation says that Mount Hood has a different volcanic make up than other Cascades volcanoes.
We’re not quite sure what it means but here’s what they say
The rocks around Mount Hood, scientists say, are almost exclusively formed from andesitic magma. And research suggests that the recharge of mafic magma to mix with its thicker felsic counterpart often occurs just prior to an actual eruption.
“The intense mixing of these two types of magma causes an increase in pressure and other effects, and is usually the trigger for an eruption,” Kent said. “But this process doesn’t happen in all volcanic events. In the Cascade Range, Mount Hood appears to be one volcano where andesitic magma and recharge-driven eruptions are dominant.”
That may be because of local crustal conditions, Kent said. Even though the Cascade Range is linked to melting rock from the Cascadia Subduction Zone, some parts of the crust are more difficult than others for magma to move through. Mount Hood appears to be in a region where it takes the extra pressure of magma mixing to cause an eruption.