A Real-Time CISN Test Bed for the ElarmS Early Warning Algorithm

Douglas Neuhauser, Alexei Kireev, Gilead Wurman, Peggy Hellweg and Richard M. Allen
University of California Berkeley

AGU Fall Meeting, San Francisco, December 2007.

The ElarmS earthquake early warning (EEW) algorithm, initially designed and tested on data collected from earthquake in southern California, is being tested on real-time network data from the California Integrated Seismic Network. In order to take advantage of the real-time broadband and strong motion data available in California, we have decomposed the ElarmS algorithm into several fundamental components: a waveform processing and phase detection module, and the ElarmS event processing module (EVM).

Using a framework generator developed by Caltech that automatically generates stub code for waveform processing, we implemented the E waveform processing algorithms for filtering, tau-p, and phase detection in a separate real-time module that runs at the distributed CISN waveform acquisition and processing centers at UC Berkeley, USGS Menlo Park, and Caltech. We developed a low latency real-time distribution system to distribute and aggregate the processed waveform attributes to one or more ElarmS processing centers. A newly developed API provides the EVM component of the ElarmS algorithm with the real-time waveform attributes and phase detections.

In order to monitor, analyse and refine the ElarmS algorithm, we implemented a real-time monitoring module that monitors the state of EVM, which archives all processed waveform data in the order they were received whenever EVM detects an event or aborts. The waveform datasets will allow us to replay the exact waveform sequence seen in real-time in order to identify coding or algorithmic problems, and to evaluate refinements in the ElarmS EVM algorithm. The monitoring system also controls the event post-processing software used to generate the ElarmS Alertmaps and event web pages, and to submit data to the CISN EEW algorithm evaluation database developed by SCEC.

© Richard M Allen