M6.0 Parkfield, September 28, 2004

The long-awaited Parkfield Earthquake on September 28 was felt in both the Los Angeles and San Francisco areas. This created a huge surge of traffic on the all of the earthquake program web servers.

Here is the traffic on the Earthquake Hazards Program web site, and the Western Region web site in Menlo Park. These graphs are made from the logs from Akamai. The Program site peak is 1946 requests/sec, and the Menlo Park peak is 8228/sec, which is the highest peak seen to date on the earthquake program servers. On both sites, the peak occurred 5 minutes after the event origin time. Normally, the peak is about 3 minutes after the event, but in this case, most of the traffic came from the metropolitan areas, and the travel time for S waves is on the order of a minute to the Los Angeles and San Francisco areas.

The Pasadena and NEIC sites both experienced traffic surges, but they were much smaller. The peak in Pasadena was 153 requests/sec, and the NEIC peak was 107.

All of these sites are served through the Akamai EdgeSuite service, so none of these sites experienced any availability problems after this event.

In the case of the Pasadena server, the Community Internet Intensity Map was the secondary destination that drove traffic to the site after the event. There were over 7,000 questionnaires submitted for this event in the first hour. In addition, the earthquake mailing lists gained nearly 2,000 new subscribers in the first 24 hours after this event. Graphs of the mailing list activity can be seen at:


Stan Schwarz
Honeywell Technical Services
Southern California Seismic Network Contract
Pasadena, California
September 30, 2004