Moment Tensor Homepage

The Berkeley Seismological Laboratory (BSL) routinely determines moment tensors for events occurring in Central and Northern California, and for notable earthquakes in the western US. Most of the mechanisms, particularly for California events, have been migrated from the old flat file catalog to the database of the Northern California Seismic System.

In the past, the BSL operated two automated moment tensor algorithms. Currently, only the three-component complete waveform inversion is used to attempt a preliminary (automatic) moment tensor solution within 6-9 minutes of an earthquake. Excellent solutions (variance reduction > 80%) are posted automatically to the web. All events with M>3.5, are reviewed by an analyst. If a solution is deemed acceptable, it is submitted to the database, disseminated via email and is posted to the web.