Information about the Keilis-Borok California Earthquake Prediction

USGS Director's Letter to California Delegation

California Earthquake Prediction Evaluation Council Report (PDF)

California Geological Survey Statement


Frequently-Asked Questions

What exactly is the prediction?

small map of prediction area The prediction is for a magnitude 6.4 or greater earthquake to occur between January 5 and September 5, 2004, within a 12,440 sq. miles area of southern California that includes portions of the eastern Mojave Desert, Coachella Valley, Imperial Valley (San Bernardino, Riverside and Imperial Counties) and eastern San Diego County. Click on the map for a larger version.

Is the prediction true? Are we going to have a large earthquake?

We don't know. The Keilis-Borork team has just begun the test of this prediction technique and has not yet issued enough predictions to evaluate whether or not the approach is successful. It’s notable because of the group’s apparent success in predicting the magnitude 8.1 earthquake in Hokkaido, Japan in September 2003 and last December’s magnitude 6.5 San Simeon quake. However, those predictions also covered very large areas so there was some chance the earthquakes would have happened anyway. Many more predictions will be needed to determine if this technique is providing a more accurate prediction than we can get anyway from our past history. Moreover, the current prediction region encloses many hazardous faults including portions of the San Andreas, San Jacinto, Imperial and Elsinore, plus the desert region that hosted the Landers and Hector Mines earthquakes, and thus has a 10-15% chance of a M≥6.4 earthquake in _any_ 9 month period. An earthquake on any one of these faults would count as a success, so even if the prediction is correct, you cannot know if your community will be affected.

How did they come up with the prediction?

The prediction method the Keilis-Borok team uses is based on identifying patterns of small earthquakes as precursors to large ones. These small earthquakes occurred last fall and the prediction window is 9 months from the end of that earthquake cluster.

Are USGS scientists ignoring the prediction?

No. The work of the Keilis-Borok team is a legitimate approach to earthquake prediction research. However, the method is unproven, and it will take much additional study, and many additional trial predictions, before it can be shown whether it works, and how well. If the method, or one like it, is eventually shown to work, it will demonstrate that the Earth’s crust contains information about upcoming large shocks. This would be an important finding, and would spur additional research that might someday lead to societally useful predictions.

What special action is California taking based on this prediction?

In February, experts from U.S. Geological Survey, California Geological Survey, the Southern California Earthquake Center and others reviewed the Keilis-Borok prediction. Dr. Keilis-Borok and his colleagues presented their methods and findings and engaged in frank discussion with about 30 invited scientists and public officials. The California Earthquake Prediction Evaluation Council attended and concluded that the Keilis-Borok methodology is a legitimate approach in earthquake prediction research, but that, while the prediction serves as a reminder for vigilance in earthquake-prone areas, “the results do not at this time warrant any special public policy actions in California.”

What can Southern Californians learn from this prediction?

Southern Californians should take the Keilis-Borok predictions as strong reminders that earthquakes have happened and will happen again in the region. And they should keep doing what the earthquake community has preached for many years: Prepare for the inevitable. Whether they happen in the next 9 months or the next 9 years, earthquakes in California will happen, and we need to be ready.

Whether it’s called preparedness, mitigation, sustainability, earthquake resistance, or disaster-resiliency, it all means the same thing. Earthquakes will happen and a prepared California is a safer California. Californians live in earthquake country, but they can prepare by ensuring that building codes are up-to-date and enforced, that older buildings are properly retrofitted to withstand earthquakes and that families and individuals are prepared. By reading and following the advice in a great new guide, Putting Down Roots in Earthquake Country you’ll go a long way towards being prepared for California’s inevitable temblors.

Until then, rest assured that USGS and its partners are doing everything possible to understand and monitor how the earth works and to reduce earthquake risk.