Mount Spurr’s Rumblings: An Alaskan Volcano Watch
The daunting task of predicting volcanic eruptions with pinpoint accuracy remains a persistent challenge for scientists worldwide. However, in the vast and rugged landscape of Alaska, Mount Spurr, a snow-laden giant located a mere 75 miles (120 kilometers) west of Anchorage, is exhibiting telltale signs that have captured the keen attention of volcanologists.
The Alaska Volcano Observatory (AVO), the vigilant guardian of Alaska’s volcanic activity, has issued a cautionary statement indicating a heightened probability of an explosive eruption from Mount Spurr in the coming weeks or months. This declaration, disseminated through the U.S. Geological Survey’s website on Wednesday, has placed the region on high alert.
While volcanologists anticipate a symphony of pre-eruption signals – increased gas emissions, heightened seismic activity, and elevated heat levels – the unpredictable nature of volcanoes dictates that Mount Spurr could also unleash its fury without any further warning. This inherent uncertainty underscores the delicate balance between scientific observation and the raw power of nature.
The current episode of volcanic unrest at Mount Spurr was first detected in April of the previous year. Scientists at the AVO registered an uncharacteristic surge in the number of earthquakes originating beneath the volcano’s surface. From April to early October, the volcano averaged approximately 30 earthquakes per week. This figure experienced a dramatic increase from early October to early February, soaring to an average of 125 earthquakes per week. While the weekly rate has recently subsided slightly to around 100 earthquakes, the sustained elevated levels continue to raise concerns.
Adding to the unease, AVO scientists also documented ground deformation along Mount Spurr’s flanks in April. Though the ground displacement has been relatively modest, measuring only 2.6 inches (6.5 centimeters), it serves as a potential indicator of the accumulation of magma, fluids, or gases beneath the volcano’s surface. Such subterranean shifts are often precursors to eruptive events.
Furthermore, a lake mysteriously appeared atop Mount Spurr’s icy summit during the summer months. This unusual occurrence suggests an increase in heat within the volcano’s crater, further fueling concerns about an impending eruption. The presence of a summit lake can indicate that the internal temperature of the volcano is rising, potentially leading to a build-up of pressure and ultimately an eruption.
Recent measurements have revealed elevated emissions of sulfur dioxide (SO2) from the summit and carbon dioxide (CO2) from both the summit and Crater Peak, a volcanic vent located just 2 miles (3.5 km) from Mount Spurr’s summit. Crater Peak now exhibits active gas vents, a clear indication that volcanic activity is intensifying in this area.
"The current unrest at Mount Spurr indicates that new magma has intruded into the Earth’s crust beneath the volcano and that the probability of an eruption has increased," the Wednesday AVO statement emphasized. The statement further suggests that magma may have been accumulating beneath Mount Spurr’s summit for several months. The recent gas data, the AVO believes, point to the emergence of a new pathway towards the Crater Peak vent, implying that fresh magma could potentially rise and erupt there.
The AVO statement clarifies that the most probable scenario is an explosive eruption, or a series of eruptions, originating from Crater Peak vent, echoing the events of 1953 and 1992. Mount Spurr’s last eruption from its summit occurred thousands of years ago, making the potential for an eruption from Crater Peak the primary focus of concern.
David Fee, a coordinating scientist from the University of Alaska Fairbanks’s Geophysical Institute, elaborated on the AVO’s approach in an interview with CNN. "We use a lot of our knowledge from past eruptions to kind of see what we think might happen in the future," Fee explained. The historical record of volcanic activity provides valuable insights into potential eruption patterns and impacts.
If a future eruption mirrors the events of 1953 and 1992, it would likely involve "one or more explosive events, each lasting as long as a few hours, [producing] ash clouds carried downwind for hundreds of miles and minor ashfall (up to about 0.25 inches) over south central Alaska." The flanks of Mount Spurr would likely be swept by pyroclastic flows, extremely hot and fast-moving avalanches of gas and volcanic debris, and impacted by ballistic showers, a barrage of flying rocks ejected from the volcano.
The AVO statement also cautions about the potential for mudflows, known as lahars, which "could inundate the upper Chakachatna River valley." These destructive flows can pose a significant threat to infrastructure and communities located downstream from the volcano.
Despite the heightened state of alert, scientists do not anticipate an imminent eruption. "If we were to see strong, sustained volcanic tremors, that would be kind of a telltale sign that we think an eruption is much closer," Fee told Alaska Beacon. "We have not seen that yet, and we’re looking very closely for any signs of it. There could be other signs as well." The presence of sustained volcanic tremors would indicate that magma is rapidly moving towards the surface, significantly increasing the likelihood of an eruption.
"At the current level of unrest, we plan to conduct routine overflights to measure gas emissions, evaluate surface changes, and measure ground surface temperatures," the AVO statement concludes. These monitoring activities are crucial for tracking the volcano’s behavior and providing early warnings of any escalating activity.
The situation at Mount Spurr serves as a stark reminder of the powerful forces that shape our planet and the challenges of predicting volcanic eruptions with absolute certainty. The AVO’s vigilant monitoring and clear communication of the risks are essential for ensuring the safety of communities and infrastructure in the vicinity of this restless Alaskan volcano. The coming weeks and months will be a period of heightened observation as scientists continue to decipher the signals emanating from Mount Spurr and prepare for the possibility of an explosive eruption.
