Mount Adams Volcano Experiences Unusual Earthquake Activity Without Eruption Threat

In September, six low-intensity earthquakes were recorded beneath Mount Adams, marking the highest monthly total since monitoring began in 1982. Despite this seismic uptick, experts state that there is no immediate threat of eruption. The volcano is primarily characterized by thick lava flows rather than explosive activity, and volcanic mudflows (lahars) present the most significant risk to nearby areas in the event of an eruption.

In September, Mount Adams in Southwest Washington experienced an unusual uptick in seismic activity, with six low-intensity earthquakes recorded by the U.S. Geological Survey’s Cascades Volcano Observatory. This number constitutes the highest monthly earthquake count observed since monitoring commenced in 1982 for the 12,276-foot volcano. Despite this heightened activity, officials assert that there is no immediate threat of eruption; the last eruption of Mount Adams occurred between 3,800 and 7,600 years ago. The recent seismic events registered magnitudes ranging from 0.9 to 2.0. According to Holly Weiss-Racine, a geologist at the Observatory, these events were deemed “extremely small” and would have gone unnoticed by residents in the area. Typically, Mount Adams experiences about one earthquake biennially. Although Weiss-Racine acknowledged the September surge as fascinating, she emphasized that it lacks significant implications for the volcano’s potential unrest. Weiss-Racine elaborated on the indicators that often signal a volcano may be entering a period of unrest, which include significant earthquakes, ground deformation, and increased gas emissions. “Right now, we’re not seeing any of those things,” she confirmed. Rather, the six observed earthquakes are categorized as routine activity. Volcanic activity can vary widely, as seen with Mount Rainier, which may experience several minor tremors daily. Should Mount Adams erupt, its potential consequences would differ from the catastrophic eruption of Mount St. Helens in 1980, which resulted in numerous fatalities and widespread ash dispersion. “It’s not a very explosive volcano. It doesn’t produce a lot of ash,” stated Weiss-Racine, noting that geological records suggest the volcano is apt to produce thick, viscous lava flows. The accumulation of such material is why Mount Adams is recognized as the largest volcano in the Cascade Range by volume. A legitimate concern in the event of an eruption would be lahars — volcanic mudflows that could emerge even from smaller eruptions. These hazardous mudflows, composed of melted glacier ice and debris, could surge through river valleys and potentially threaten populated regions, such as Trout Lake in Klickitat County. The recent seismic activity was concentrated beneath the volcano’s center; however, the limited monitoring capabilities — with only one station situated seven miles southwest of the summit — hinder accurate assessment of the event’s origin and depth. To address this limitation, the Cascades Volcano Observatory has installed a temporary seismic station and intends to introduce two additional stations for enhanced monitoring of Mount Adams. Congress authorized the establishment of a new volcano monitoring and warning system in 2019, prompting the USGS to pursue the installation of four additional monitoring sites at Mount Adams, contingent upon permits from the U.S. Forest Service. Weiss-Racine indicated that Forest Service approvals could conclude within the month, yet the installation of the permanent stations may be postponed until the forthcoming year due to deteriorating winter weather conditions around the mountain.

Mount Adams is a prominent volcano located in the Cascade Range of Southwest Washington. It is characterized by its substantial elevation of 12,276 feet and has a history of eruptions, the last of which occurred thousands of years ago. The mountain’s seismic activity is closely monitored by experts due to its potential impact on surrounding communities. Seismic activity, including earthquakes, while generally not indicative of an imminent eruption, is closely observed for any significant increases that might change the risk assessment. The geologic makeup of Mount Adams suggests a different eruption style as compared to other regional volcanoes, and the potential threat primarily revolves around lahars in the event of an eruption, a concern due to its influence on local populations.

The recent increase in earthquake activity beneath Mount Adams is notable, marking the highest recorded monthly count since monitoring began. However, experts assert that there is currently no cause for alarm regarding an imminent eruption. Continuous monitoring and the planned upgrades to the seismic network will enhance understanding and preparedness for future volcanic activity. The unique geologic characteristics of Mount Adams indicate that, should an eruption occur, it would primarily pose risks associated with lahars rather than explosive ash emissions.

Original Source: www.seattletimes.com