Seismic activity is typically associated with tectonic plate movements and volcanic eruptions, but it can also have unconventional triggers, including floods, excited crowds, and glaciers.
In the Washington Cascades, researchers have identified “glacier quakes” as a unique source of seismic events, offering valuable insights into seismic activity, glacier behavior, and climate-related phenomena.
Washington is no stranger to seismic activity, as it lies within the Pacific Ring of Fire, a region prone to earthquakes and volcanic eruptions. The catastrophic 1980 eruption of Mount St. Helens and the looming threat of a major earthquake in the Cascadia Subduction Zone highlight the state’s vulnerability to such events.
Glacier quakes in the Washington Cascades are predominantly observed during the summer months when glaciers exhibit increased movement. Seismometers record these glacier-induced quakes, which can be similar in magnitude to regular earthquakes, reaching up to magnitude 3. Similar glacier quakes have been detected in Alaska, particularly in the Southcentral region, exhibiting a similar seasonal pattern. The influx of visitors to national parks and hiking sites has brought attention to these glacier quakes.
Various glacier-related phenomena can trigger these seismic events, including crevasse formation, stick-slip behavior at the glacier-ice interface, and the calving of tidewater glaciers. While glacier quakes are often observed on volcanoes due to the abundance of seismometer networks, they can occur anywhere with substantial glaciers and suitable seismic monitoring.
Some glacier quakes are too minor for people to perceive, while others, like the repeating Easton Glacier terminus quake, can be recorded on seismometers located up to 100 kilometers away. Researchers are particularly intrigued by the consistent waveform of this specific quake, suggesting it originates from the same location with minimal variations over time.
Notably, glacier quakes do not pose a significant threat to tourists or nearby communities, in contrast to traditional earthquakes that can cause destruction and loss of life. As technology improves and access to remote areas becomes more feasible, scientists can continue to analyze the data from these glacier quakes to enhance our understanding of glacier dynamics, climate patterns, and ice flow.
Despite initial concerns when these quakes were first detected on seismometers, researchers have since distinguished them from volcanic activity. These glacier quakes are too small to trigger volcanic events, and as technology and access to these areas advance, seismologists and climatologists will gain a deeper understanding of glacier movements and their correlation with climate patterns and ice flow.
https://phys.org/news/2023-10-washington-volcanoes-experiencing-seismic-tremors.html