Mount Saint Helens in Washington State is an infamous American wonder; a volcanic dome which up until recently was thought to be dormant. Slowly but surely, this famous volcano is showing signs that it is awakening as magma levels rise beneath the surface, “re-pressurizing” and positioning the dome for future eruption.
In a statement issued Wednesday, the U.S. Geological Survey (USGS) said that the reservoir of magma four to six miles below the 8,363-foot peak is definitely rising. It may sound alarming, especially to Washington residents living by the mountain. The USGS statement indicated that there was nothing to fear, for now.
Carolyn Driedger, spokeswoman for the Vancouver-based USGS Cascades Volcano Observatory (CVO), described the upward movement of the magma as “slight and subtle.” The underground reservoir is rising so slowly that the measurement its upward activity over the last five decades has been compared to the length of a thumbnail.
Although Mount Saint Helens has been in an active period since its eruption in 1980, which killed 57 people and caused almost $3 billion in damages in terms of 2014 money, Driedger said its slight changes indicate it may be another 100 years before another eruption.
Scientists have had their suspicions about the rise in levels of magma, possibly awakening Mount Saint Helens. In lieu of the 4-year steam eruption that lasted from 2004 to 2008, USGS and PNSN scientists have been studying the gradual, barely measurable inflation of ground surface and earthquake activity in recent years. The ground inflation and minor seismic activity have served as clues worth surveillance because of their similarity to the activity after the eruption in 1980.
Since the end of a four-year steam eruption at Mount St. Helens between 2004 and 2008, scientists have focused surveillance on small earthquakes and ground changes resembling those seen in the years following the 1980-1986 eruptions.
According to the USGS statement, Mount St. Helens has been recharging since 2008, likely as a result of trace amounts of additional magma arriving beneath the ground surface. Scientists indicate that this is a fairly common observance in volcanic mountains following eruptions. Most other cases of the scorching tectonic phenomenon prove that it is no indication of imminent danger.
Nonetheless, USGS and PNSN will keep a close eye on ground deformation and seismic activity taking place at Mount St. Helens. They are preparing to conduct additional measurements over the summer to learn more specific information about what is taking place beneath the volcano.
The additional measurements will look at different indicators than those that determined the re-pressurization announced in Wednesday’s statement. Scientists will look at what kind of volcanic gases are being released as well as the amounts. They will also conduct surveys to measure the strength of the gravity field at the volcano. These additional studies are expected to give scientists an accurate sense of whether the magma reservoir changes in amount or depth.
Despite the thorough, ongoing investigation of the magma levels rising in the awakening of Mount Saint Helens, Seth Moran, a seismologist with USGS, reassures that the volcano is likely to sit quietly for a long time to come. When that changes, everyone will know. “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,” Moran said.
By Erica Salcuni