Seismometers at Mount Rainier recorded a 72-hour burst of underground vibrations starting November 15, 2025, around 5 a.m. ET, relevant to the Seattle–Tacoma area. The Mount Rainier tremor follows July 2025 earthquake swarms of 1,000+ small quakes, peaking at 41 per hour. USGS and PNSN link the shaking to the hydrothermal system; the alert remains GREEN NORMAL.
About 300,000 residents lie in mapped hazard pathways, including more than 80,000 in lahar valleys. Orting and Puyallup face lahar travel times of roughly 30–45 minutes and 1–3 hours.
During eruptions, glacier melt can drive lahars exceeding 60 mph. Twenty seismic stations monitor Rainier; no stronger tremor, deep earthquakes, or ground swelling are reported.
