by Allan Holmes

Digital Earthquake Maps Pinpoint Damage

Sep 01, 20052 mins
InternetWeb Development

When four earthquakes of magnitudes ranging from 4.9 to 7.2 rattled the West Coast in June, Marcia McLaren, a seismologist with Pacific Gas & Electric (PG&E), was better prepared than she was a year and a half ago, when a 6.5 magnitude quake shook the San Simeon region. In the first disaster, the utility’s sites and networks weren’t damaged, but that took awhile to determine, as McLaren and her team made dozens of calls to managers in the field.

After that experience, McLaren installed ShakeCast, a service launched last year by the U.S. Geological Survey (USGS), which provides companies with real-time earthquake data that they can use for damage assessment. Within minutes of an earthquake, ShakeCast collects ground-shaking data from underground sensors and produces a ShakeMap, which displays the distribution of shaking intensity in the areas affected by the quake. From there, the ShakeMap is sent to participating companies. Companies can also sign up to receive damage estimates. (For more about ShakeCast, visit

Now, when an earthquake with a magnitude of at least 3.5 hits anywhere in PG&E’s service area (which occurs almost monthly), McLaren receives a pager message and an e-mail from USGS giving her details about the quake. She then retrieves her color-coded ShakeMap that shows where different magnitudes of shaking occurred. An internal PG&E application overlays a map of the utility’s facilities, telling McLaren which ones may have been affected. With this information, she can prioritize which managers to contact and what procedures must be followed.

The June earthquakes occurred too far away from PG&E’s service area to cause any damage to company facilities. Meanwhile, McLaren has demonstrated ShakeCast to company executives, showing them how they can use the service to make disaster recovery decisions more quickly and corral the costs of future earthquake damage.