Researchers at the University of Utah have developed a detailed image of deep volcanic plumbing and partly molten rock of Mount Rainier that they think will erupt again someday.
The image was developed after measuring the Earth’s power to conduct electricity and seismic waves.
Geophysicist Phil Wannamaker said, “This is the most direct image yet capturing the melting process that feeds magma into a crustal reservoir that eventually is tapped for eruptions.”
“But it does not provide any information on the timing of future eruptions from Mount Rainier or other Cascade Range volcanoes,” Wannamaker further said.
The findings of the study were published in the journal Nature. The National Science Foundation’s Earthscope program largely funded the experiment. Earthscope program has also made underground images of the US using seismic or sound-wave tomography.
The research was carried by Wannamaker and senior geophysicists from the College of New Jersey, the Woods Hole Oceanographic Institution in Massachusetts and the University of Bergen, Norway. Wannamaker is professor at of the university’s Energy & Geoscience Institute and Department of Civil and Environmental Engineering.
About Mount Rainier
Mount Rainier is a massive stratovolcano which has the tallest peak in the Cascades. It is located 54 miles (87 km) southeast of Seattle in the state of Washington, United States.
Mount Rainier is an active volcano that is believed to be erupting again,” says the US Geological Survey.
According to the scientists, an ancestral Rainier existed two million to one million years ago. Rainier explosively erupted while spewing ash and pumice for dozens of times during the past 11,000 years. It was 2,200 years ago when Rainier’s last lava flowed of hot rock and ash. Similarly, the last big mudflow was 500 years ago.
The image had an odd twist into it. It appeared to show that at least part of molten magma reservoir is located about 6 to 10 miles northwest of the 14,410-foot volcano.
Researchers explained that this could be due to the 80 electrical sensors, which were used for the experiment, that were placed in a 190-mile-long along west-to-east line, which is about 12 miles north of Rainier. Hence, a major share of the magma chamber could be directly under the peak, but with a lobe extending northwest under the line of detectors, Wannamaker says.
According to the researchers, the top of the magma reservoir shown in the image is about 5 miles underground and around 5 to 10 miles thick, and 5 to 10 miles wide in east-west extent,” Wannamaker says.
“We can’t really describe the north-south extent because it’s a slice view,” he said.
For Wannamaker, the reservoir is roughly 30 percent molten.
The new image fails to explain the plumbing tying Mount Rainier to the magma chamber 5 miles below it.
According to the research group, it was the most detailed cross-section view till date under a Cascades volcanic system using electrical and seismic imaging. Earlier seismic images that were used indicated water and partly molten rock atop the diving slab. The new picture also indicates melting “from the surface of the slab to the upper crust, where partly molten magma accumulates before erupting.”