What the instruments hear
Twenty-four hours of ground motion from one seismometer per drainage, and the summit, filtered to 1–10 Hz and drawn here from the raw data. Each line is an hour, Pacific time, oldest at the top. Earthquakes show as spikes, wind and rivers as a thicker trace. A lahar or large debris flow would show as a long, swelling band lasting many minutes, first on the stations high in the valley, then on the ones below.
Ground-motion level, last 7 days
RSAM (real-time seismic amplitude): the average shaking every 10 minutes, filtered to 1–10 Hz, the band where volcanic tremor and debris flows show up. It is in raw instrument counts, so compare a station with itself, not with its neighbours. Daily cycles are mostly wind, traffic and meltwater.
Pick stations
Earthquakes by depth, last 30 days
Every located earthquake within 20 km of the summit: when, how deep, and how big. Most at Rainier are shallow, a few kilometres beneath the summit, in the hydrothermal system above the magma.