Testing ElarmS on the realtime seismic system in CA

ElarmS is currently being ported to the realtime seismic systems in California. This is part of a three-year effort by the CISN to test the capabilities of several early warning algorithms in CA. At the conclusion of the project we will understand the likely timeliness and accuracy of warning should the system be implemented for public use. The project is funded by the USGS.

Data from the testing streams to the CISN EEW website at SCEC.

Automated, non-interactive processing in northern CA

Using past earthquake data from northern California the ElarmS algorithms have been expanded to use both the amplitude and the frequency content of the first few seconds of P-wave arrivals to rapidly estimate magnitude. ElarmS also now incorporates components of ShakeMap to produce and AlertMap - a map of the predicted peak ground motion - which is updated every second during the course of an earthquake (fig left).

The new algorithms have been tested by running them automatically ten minutes after all earthquakes with magnitudes greater then 3 in northern California since February 2006.

This work is presented in Wurman, Allen and Lombard, J. Geophys. Res., 112, B08311, 2007.

Probabilistic warning times in the San Francisco Bay Area

Using our knowledge of future likely earthquakes in northern CA and combining it with the time required by the ElarmS methodology to provide a warning, we can estimate the range of warning times that such a system could provide.

This work is presented in Allen, Seismo. Res. Lett., 77 (3), 371-376,2006.
The e-supplement contains warning times for different regions of the Bay Area.

The deterministic nature of earthquake rupture

The predominant period, tau-p-max, of the first few seconds of the P-wave from 71 earthquakes around the world with magnitudes ranging from 3.0 to 8.3 are measured. We find that tau-p-max scales with the magnitude of the earthquake despite the fact that the rupture is not complete by the time of the measurements for all events greater than M 4.0. We interpret this observation as suggesting that earthquake rupture is deterministic.

This work is presented in Olson and Allen, Nature, 438, 212-215,2005.

The potential for earthquake early warning

Using the existing seismic network in southern California and a dataset of past earthquakes, a methodology for rapid magnitude estimation of earthquakes is developed using the frequency content of the first few seconds of the P-wave. Given the accuracy and timeliness of the earthquakes information we suggest that it would be feasible to develop a warning system in the region.

This work is presented in Allen and Kanamori, Science, 300, 786-789, 2003.