The eruption of Mount St. Helens on May 18, 1980 has claimed 57 lives and caused serious damage to homes and infrastructure. Now, scientists have revealed that the volcano could possibly erupt again in the future based on findings of a pioneering $3 million study of the volcano's plumbing system.
Geologists who studied the volcano have found a second enormous chamber lying between seven to 23 miles beneath the surface. This massive pool of molten rock was found connected to a smaller chamber lying directly beneath the volcano.
How these two chambers are connected is helping scientists understand the sequence of events prior to the 1980 eruption, whose strength of explosion destroyed the topmost peaks of the mountain. Matching the newly discovered magma reservoirs with earthquake data also sheds light on how the deadliest eruption in U.S. history occurred.
The researchers said that the series of tremors that occurred in the months leading to the 1980 eruption may have been caused by magma pumping from the lower to the upper chamber of the volcano, which caused the pressure inside the upper chamber to dramatically increase resulting in the deadly explosion.
"We can only now understand that those earthquakes are connecting those magma reservoirs," said Rice University seismologist Eric Kiser. "They could be an indication that you have migration of fluid between the two bodies."
Reporting the findings of their study at the annual meeting of the Geological Society of America in Baltimore, Maryland on Nov. 3, the researchers said that more tremors have been observed in the area suggesting that more magma is being injected.
"A cluster of low frequency events, typically associated with injection of magma, occurs at the northwestern boundary of this low Vp column," the researchers reported. "Much of the recorded seismicity between the shallow high Vp/Vs body and deep low Vp column took place in the months preceding and hours following the May 18, 1980 eruption. This may indicate a transient migration of magma between these two reservoirs associated with this eruption."
After the 1980 eruption, the volcano started to erupt again in 2004 but it fell silent in July 2008. Nonetheless, Mount St. Helens is still considered a high risk volcano and is closely monitored by the U.S. Geological Survey.
The researchers said that their findings could offer a crucial early warning system of a potential eruption.