How likely is volcanic activity in the Long Valley area?
Based on the frequency of eruptions along the Mono-Inyo Crates volcanic chain in the past 5,000 years, the probability of an eruption occurring in any given year is somewhat less than one percent per year or roughly one chance in a few hundred in any given year. This is comparable to the annual chance of a magnitude 8 earthquake (like the Great 1906 San Francisco Earthquake) along the San Andreas Fault in coastal California or of an eruption from one of the more active Cascade Range volcanoes in the Pacific Northwest, such as Mount Rainier in Washington or Mount Shasta in California. Increased volcanic unrest (including earthquake swarms, ground deformation, and CO2 gas emissions) in the Long Valley area since 1980 increases the chance of an eruption occurring in the near future, but scientists still lack adequate data to reliably calculate by how much. Volcanic unrest in some other large volcanic systems has persisted for decades or even centuries without leading to an eruption. But s
