Forecasting The Next Great San Francisco Earthquake

The Virtual Californiaapproach to earthquake forecasting is similar to the computer modelsused for weather forecasting, said John Rundle, director of the UCDavis Computational Science and Engineering Center, who has developedthe model with colleagues from the Jet Propulsion Laboratory and otherinstitutions. A previous forecast of earthquake hazards, the WorkingGroup on California Earthquake Probabilities, used records of pastearthquakes to calculate the probability of future ones.

TheVirtual California model includes 650 segments representing the majorfault systems in California, including the San Andreas faultresponsible for the 1906 San Francisco earthquake. The simulation takesinto account the gradual movement of faults and how they interact witheach other.

The researchers used the model to simulate 40,000years of earthquakes in California. They found almost 400 major(magnitude 7 or above) earthquakes at an average interval of 101 years.The simulation data indicates a 25 percent chance of another suchearthquake in the next 20 years, a 50 percent chance in the next 45years and a 75 percent chance by 2086.

The latest work ispublished in Proceedings of the National Academy of Sciences of theUSA. Other authors on the paper are Paul Rundle, Donald Turcotte,Robert Scherbakov and Gleb Yakovlev at UC Davis; Andrea Donellan, PeggyLi and Jay Parker, Jet Propulsion Laboratory; Bruce Malamud, King'sCollege, London; Lisa Grant, UC Irvine; Geoffrey Fox, IndianaUniversity, Bloomington; Dennis McLeod, University of SouthernCalifornia; Bill Klein, Boston University; and Kristy Tiampo,University of Western Ontario, Canada.