Seismic Activity Reported at Washington’s Mount Adams: No Immediate Eruption Threat
In September, Mount Adams experienced an unusual increase in seismic activity with six low-magnitude earthquakes reported, marking the highest count for a month since 1982. Despite this, geologists indicate there is no immediate eruption threat, and historical data suggests that if an eruption were to occur, it would result in less explosive activity compared to other nearby volcanoes. Monitoring efforts are being improved to ensure safety in the region.
The U.S. Geological Survey Cascades Volcano Observatory has reported an unusual uptick in seismic activity at Mount Adams, located in Southwest Washington. In September, six low-magnitude earthquakes were detected beneath the 12,276-foot volcano. This marked the highest monthly earthquake count since monitoring began in 1982. Despite the increase in seismic activity, officials have reassured that there is no immediate threat of an eruption. The last known eruption of Mount Adams occurred approximately 3,800 to 7,600 years ago. The detected earthquakes ranged between magnitudes of 0.9 and 2.0, and were described as “extremely small” by geologist Holly Weiss-Racine, indicating that they were likely imperceptible to those in the vicinity. Typically, Mount Adams experiences seismic activity at a much lower frequency, with about one earthquake every two to three years. Weiss-Racine characterized the recent increase as interesting but not indicative of significant volcanic unrest. She elaborated that signs of a volcano entering a restless phase would include substantial increases in earthquakes, ground deformation, and heightened gas emissions. “Right now, we’re not seeing any of those things,” she noted. It is imperative to understand that volcanoes often exhibit a variety of background activities consisting of minor earthquakes. For instance, Mount Rainier can record small seismic events daily. In the event of a potential eruption at Mount Adams, historical geological deposits suggest that the eruption’s characteristics would significantly differ from the catastrophic 1980 eruption at Mount St. Helens, which resulted in numerous fatalities and global ash dispersal. “It’s not a very explosive volcano. It doesn’t produce a lot of ash,” Weiss-Racine explained. Instead, the geological records favor the possibility of thick, viscous lava flows, which contribute to Mount Adams being the largest volcano by volume in the Cascade Range. Nonetheless, lahars, or volcanic mudflows, pose a serious threat during an eruption, even minor ones. These mudflows, comprising a mixture of melted ice and volcanic rock, could rapidly descend into river valleys and potentially reach populated areas like Trout Lake in Klickitat County. The recent earthquake activity was primarily centered beneath Mount Adams; however, due to the limited monitoring infrastructure—a single station positioned seven miles southwest of the summit—determining the precise epicenter and depth of the quakes remains challenging. To address this, the Cascades Volcano Observatory has installed a temporary seismic station and plans to deploy two additional ones at the site. In 2019, Congress approved funding for a new volcano monitoring and early warning system, which USGS is advancing to establish four additional observational sites at Mount Adams. This endeavor is currently contingent on acquiring permits from the U.S. Forest Service, with hopes that approvals will be finalized within a month, although deploying the new permanent stations may be delayed until the following year due to inclement winter weather.
Mount Adams, an active volcano located in Southwest Washington, is part of the Cascade Range and has a history of eruptions, the most recent occurring several millennia ago. Monitoring efforts by the U.S. Geological Survey have been in place since 1982, and recent seismic activities have prompted a closer evaluation of its status. Typically, the volcano experiences infrequent seismic events, making the recent six earthquakes in September noteworthy. The geological characteristics of Mount Adams suggest that while an eruption could occur, it would be less explosive than others in the region, such as Mount St. Helens. Understanding the risks associated with volcanic activity, including lahars, is critical for the safety of nearby populations.
In conclusion, while the recent seismic events beneath Mount Adams indicate an unusual occurrence in September, experts have determined that there is no imminent danger of an eruption. The activity appears to fall within a normal range for volcanic monitoring, and efforts are underway to enhance monitoring capabilities. The broader geological context suggests that even in the event of an eruption, the nature of such an event would markedly differ from that of more explosive volcanic histories in the region. Continuous monitoring and research are essential to ensure public safety and preparedness.
Original Source: www.seattletimes.com
