Multimedia

Locations of earthquakes of at least magnitude 1.0 in 2025 and the outlines of the boxes CalVO uses to count earthquakes around Long Valley. Only 6 earthquakes were located inside the Long Valley Caldera box. (Earthquake location data from Northern California Seismic Network.) Figure by Alicia Hotovec-Ellis, USGS. 

Graphs of the number of earthquakes located each year since 1980 in the Long Valley Caldera and nearby Sierra Block monitoring boxes. Note that the number of earthquakes on the left shown on a logarithmic scale, which means they increase an order of magnitude with each "step." Figure by Alicia Hotovec-Ellis, USGS.

Rhyolite lava flow textures from Long Valley and Yellowstone calderas.  A) Photograph of well-developed spherulites in a lava flow from Long Valley Caldera in Eastern California. This high-silica rhyolite flow is very similar to the Central Plateau Member rhyolites of the Yellowstone Plateau Volcanic Field and exhibits many of the same textures.

This panorama of the Long Valley Caldera, looking from north to south, shows its broad central plain, post-caldera rhyolite flows and uplift on the right, and eastern Sierra Nevada in the background. USGS photo by Jessica Ball.

The presence of spherulites indicates that a lava flow cooled quickly, and their mineralogy holds clues to its precise cooling history. USGS photo by Jessica Ball

This panoramic view of the Long Valley Caldera was taken from a lava dome on the north rim of the caldera. USGS photo by Jessica Ball