What’s normal for a volcano? How CalVO scientists decide when to raise an alarm (or not)
In this spectrogram from November 30, 2024, at Mammoth Mountain, earthquakes in a swarm appear as bright blips of color, arriving rapid-fire and very close in time at nearby stations. Every day, CalVO duty scientists check the number, intensity, and character of earthquakes happening at our volcanoes. It's actually quite common for an active volcano - meaning one that has eruptible magma somewhere in its plumbing - to experience small quakes and shakes. There's always something going on, whether it's magma gurgling, gases and fluids flowing through a hydrothermal system, or the bulk of the volcano settling and shifting. The