07/08/2025
Seismic Advisory: Mount Rainier Swarm Activity – July 8, 2025
Over 400 shallow volcano-tectonic (VT) earthquakes have been recorded beneath the summit of Mount Rainier in the past 24 hours, marking the most active swarm since 2009, when over 1,000 similar quakes occurred over the span of several days.
These VT quakes, mostly within 1.5 to 3.7 miles (2–6 km) depth, suggest rock fracturing likely caused by hydrothermal fluid movement, not magma. This is supported by the absence of deformation, gas emissions, or long-period (LP) tremor typically associated with rising magma.
Mount Rainier’s last comparable swarm in 2009 also consisted of shallow VT earthquakes with no eruption. Then, as now, the seismic signatures pointed to a dynamic hydrothermal system—not a magmatic intrusion.
At this time:
🔹 No volcanic gas anomalies (SO₂, CO₂) have been detected
🔹 No uplift or tilt is showing in GPS or ground sensors
🔹 Alert level remains at GREEN (Normal) per the USGS and Cascades Volcano Observatory
As always, KB Tenacious remains committed to public safety and information. While this swarm does not currently indicate an eruption, volcanic systems can evolve, and we will continue tracking updates from official agencies and field data.
Credit to StormChaser Kenneth Schneider for the use of the professional and informative radar system that supplied us all the relevant data for this post.
