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The location of GPS station KRAC and its predecessor KRAK, slightly north of the center of deflation in Long Valley. USGS figure by Josh Crozier and Alicia Hotovec-Ellis.
The location of GPS station KRAC and its predecessor KRAK, slightly north of the center of deflation in Long Valley. USGS figure by Josh Crozier and Alicia Hotovec-Ellis.
The average of individual measurements from GPS station KRAC/KRAK shows about 6 cm of ground subsidence since 2021. The multi-year deflation stands out above smaller fluctuations caused by noise in the data and seasonal water infiltration (the peaks and troughs in the dots for individual measurements). USGS figure by Josh Crozier and Alicia Hotovec-Ellis.
The average of individual measurements from GPS station KRAC/KRAK shows about 6 cm of ground subsidence since 2021. The multi-year deflation stands out above smaller fluctuations caused by noise in the data and seasonal water infiltration (the peaks and troughs in the dots for individual measurements). USGS figure by Josh Crozier and Alicia Hotovec-Ellis.
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.
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.
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.
This seismic station in the Lassen Volcanic Center was damaged during the Dixie Fire of 2021, which burned huge swathes of forest in the Lassen Volcanic National Park. Above-ground equipment, including the tree that held the antenna and solar panel above winter snows, was destroyed; belowground seismic sensors were recoverable. USGS photo by Ryan Presser, NCSN.
This seismic station in the Lassen Volcanic Center was damaged during the Dixie Fire of 2021, which burned huge swathes of forest in the Lassen Volcanic National Park. Above-ground equipment, including the tree that held the antenna and solar panel above winter snows, was destroyed; belowground seismic sensors were recoverable. USGS photo by Ryan Presser, NCSN.
The California Volcano Observatory was created in 2012. Its logo shows Mount Shasta with a California grizzly bear (extinct) in the foreground.
The California Volcano Observatory was created in 2012. Its logo shows Mount Shasta with a California grizzly bear (extinct) in the foreground.