USGS scientists Wes Thelen and Alex Iezzi talk about what they are doing to learn more about recent earthquake activity at Mount Adams (November 20, 2024)

In September, the USGS Cascades Volcano Observatory (CVO) and Pacific Northwest Seismic Network (PNSN) located six earthquakes at Mount Adams ranging in magnitudes from 0.9 to 2.0. While six doesn’t sound like much, earthquakes at this volcano are typically located at a rate of about one earthquake every two to three years.

With permission, CVO scientists rapidly installed three temporary seismic stations closer to the volcano to enlarge the permanent monitoring network. The temporary stations included a seismometer buried in the ground, a plastic case that contained batteries charged by a solar panel, and a cell antenna so data could be transmitted to CVO and PNSN in real-time.

The temporary stations have been transmitting data for almost two months. During that time, scientists have located two additional earthquakes above magnitude 0.9. One was located in October, and one in early November. While the data collected so far have been useful, it hasn’t provided a full picture of what’s happening under the volcano. For that, stations will need to record tens or hundreds of earthquakes over the course of decades.

In general, volcanoes tend to have seismicity that waxes and wanes over time, which is considered normal. Currently, there is no indication that the level of earthquake activity is cause for concern, so the alert level and color code for Mount Adams remain at GREEN / NORMAL.

The temporary stations are just that, temporary. One station located on the volcano was not designed to withstand heavy snow loads and strong winds and will need to be removed soon. With the other two temporary stations and the permanent network around Mount Adams, CVO and PNSN will continue to locate earthquakes above magnitude 0.9. If there was a dramatic increase in the number of earthquakes above magnitude 0.9, CVO would be able to respond quickly using the same type of rapid deployment system used in early October.

The recent events have provided an opportunity to work with emergency managers, land managers, and landowners to help improve our monitoring capabilities at Mount Adams with network expansions vital to the National Volcano Early Warning System authorized in 2019. It has also been a time to engage with local communities to raise awareness about potential hazards, so everyone is prepared for different types of volcanic events, large or small.