Researchers at the U.S. Geological Survey (USGS) confirmed that the volcano in the Washington state is telling signs of an impending "long-term uplift" and they have recorded a few minor earthquake activities already. The activity, they found lately, was due to the volcano's magma reservoir "re-pressurizing" five miles below.
The 8,363-foot volcano is busy churning molten rocks inside, which have been reportedly recharging Mount St. Helens since its reawakening after the 1980 eruption that went from October 2004 to January 2008. The almost four-year long eruption molded Mount St. Helens a new lava dome.
"This is probably what Mount St. Helens does," said Seth Moran, a volcano seismologist at USGS. "It may stay perched at ready stage for a long time before it starts to erupt. The reassuring thing is: when it's really ready to erupt, it gives lots and lots of signs."
The "long-term uplift" is not detrimental, added Moran, as it moves at a glacial phase. It only recorded a mere thumbnail-length in the past six years and this similar activity reminded them of the post-1980 eruption.
The most active volcano in the Cascade Range Volcanic Arc, a segment of the Pacific Ring of Fire, Mount St. Helens is most notorious for its major eruption on May 18, 1980. Without warning, a 5.1 earthquake triggered the largest avalanche in history, which subsequently lifted pressure on the volcano's magma system.
The de-pressurizing ignited a furious lateral blast shooting hot rocks, ash and volcanic gas 300 miles per hour. Pyroclastic flows were released and it swept over forests at 50 to 80 miles per hour. A total of 57 people died from the disaster and an estimated 7,000 animals living in the forests were believed to have been wiped out by the seething lava.
Before the 1980 eruption, Mount St. Helens is the fifth highest mountain the Washington, with its summit altitude reaching 9,677 feet. The post-eruption, however, caused Mount St. Helens to lose approximately 1,314 feet with its peak reduced to 2.6 billion cubic meters, leaving behind a horseshoe-shaped opening deep enough to avert the repeat of the major eruption.
Mount St. Helens is named after the British diplomat Lord St. Helens, a friend of renowned North American explorer George Vancouver.
The USGS team monitoring Mount St. Helens' activity is composed of the USGS' Cascades Volcano Observatory and the Pacific Northwest Seismic Network.