Official

Medicine Lake Volcano part of newly-designated Sáttítla Highlands National Monument

Aerial view west across the upper part of Medicine Lake Volcano toward Mount Shasta, with the caldera lake labeled in the distance.

The volcano has erupted numerous times over its half-million-year history, including 9 times in the last 5,000 years. The youngest among these eruptions created the 950-year-old Glass Mountain flow, a known source of obsidian for indigenous people. The name “Sáttítla” translates to “obsidian place” in the Ajumawi language.

The volcano, although currently dormant, is considered active with the ability to erupt again in human lifetimes. As a result, it has been designated by the USGS as a “high threat volcano” and is constantly monitored by the California Volcano Observatory, consistent with the plans laid out in the USGS National Volcano Early Warning System (NVEWS). The area of the new monument that is located west of Medicine Lake volcano is also volcanic terrain. Earthquake swarms associated with a dike intrusion were detected in the Tennant area about 25 km west of Medicine Lake in the 1970s.

There are six seismic stations within the boundaries of the new National Monument, three of which were updated from legacy analog to modern digital seismometers just last summer. GNSS (GPS) stations to monitor deformation are also part of the mix, with three inside the Sáttítla Highlands National Monument boundaries (and one of those inside the Medicine Lake caldera itself). Instruments like these allow us to better track seismic activity and ground movements associated with potential magma movement at depth.

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