New research on Mount Hood in Oregon into how magma is stored below suggests that volcanoes can blow up with liquid hot magma in a lot less time, but most of the time, they contain magma that has been kept cool, near-solid state for thousands of years.
Mount Hood, an 11,200-foot volcano last erupted 220 years ago and is now considered dormant.
Almost for 100,000 years, a husk of cool magma has been residing mostly static underneath the Mt. Hood volcano.
The cool magma is like peanut butter directly from the fridge — hard to move.
According to the new study, published in the journal Nature researchers believe that this information could help scientists to better forecast flare-up by examining volcanoes for liquid magma.
Hot magma from deep in the Earth’s crust bubbles up, mixes with the cool magma and causes it to liquefy.
“Some people imagine that beneath a volcano is a bubbling vat of magma just ready to go at any time,” said Adam Kent, a geologist at Oregon State University. “But we’ve found that the magma under Mt. Hood is in this mobile state maybe less than 1% of the total time it has been there.”
“If the temperature of the rock is too cold, the magma is like peanut butter in a refrigerator,” said Ken.
For Mount Hood, the threshold seems to be about 750 degrees Celsius – if it warms up just 50 to 75 degrees above that, it greatly increases the viscosity of the magma and makes it easier to mobilize.”
Kent along with his team observed the crystals there inside Mount Hood, which shaped when the volcano’s magma first climb up through the Earth’s crust into its current chamber. The age of the crystals was measured by observing the rate of decomposition of naturally occurring radioactive elements in them.
“This tells us that the standard state of magma for this system is that it can’t be erupted,” Kari Cooper, a geochemist at the University of California, Davis, and co-author of the study.
“That means that having a magma that can erupt is a special condition. Our expectation is that there are a lot of volcanoes that behave this way.”
The study was funded by the National Science Foundation. Kent said researchers could conceivably use seismic waves to detect when the magma pod beneath Mt. Hood has liquid present. This would mean that there is a possibility of eruption.
According to researchers the technique of monitoring liquid lava isn’t a fail-safe method for the prediction of eruptions but should be considered against the background of several other pointers, counting seismic activity and gases.
“If you can see a body of magma that has a high amount of liquid, perhaps this magma is getting ready to erupt or at least has some potential to erupt,” Kent said. “It wouldn’t be a slam-dunk guarantee.”
Mount Hood’s magma reservoir sits about 2.5 to 3 miles beneath the surface. According to the analysis of the volcano’s crystals, its temperature is usually 1,380 degrees Fahrenheit.
The next step in this research is to learn more about cool magma pods beneath other, larger volcanoes.