|
Mapping Earthquakes Online
Sensors, Questionnaires Create Detailed Web-Based Quake Info
 Listen to Andy
Bowers' report for Weekend Edition Sunday.
Seismologist David Wald explains the difference between earthquake magnitude and intensity.
|
|
Monday, Jan. 17, 1994, 4:30 AM -- a devastating 6.7 temblor centered in Northridge shakes awake a wide area of Southern California.
Graphic courtesy TriNet
 enlarge image
|
March 10, 2002 -- A new high-tech earthquake sensing system developed by the U.S. Geological Survey and the California Institute of Technology in Pasadena is allowing a more rapid dissemination of information about the magnitude, epicenter and intensity of quakes. And it's also allowing residents of areas affected by quakes to share their own experiences online.
The system was developed to help emergency crews identify the hardest-hit areas in less than five minutes after a major temblor -- because lives can depend on the speed of emergency response. And as NPR's Andy Bowers discovered, it's a system anyone with an Internet connection can use.
The system was developed after the 1994 Northridge earthquake, a 6.7 magnitude quake centered in the suburban valley area outside of Los Angeles. The cost was enormous: at least 61 lives and $15 billion in damage.
 |
|
"When you get online and take a look at these maps on our Web site, you'll be able to see whether your grandma in Pasadena was affected or not."
David Wald, a seismologist with the U.S. Geological Survey, on just one of the benefits of the TriNet earthquake mapping system.
|
|
It took more than 30 minutes for geologists to determine the magnitude and epicenter of the quake, because the network of seismic sensors used to gather that information was simply not up to the task.
"We were working with 70s technology, and so we were swamped, right after that earthquake," said David Wald, a seismologist at U.S.G.S. Wald and his colleagues realized they needed an improved system of ground sensors, all linked to computers that could process the data automatically and pinpoint areas where the ground shook the hardest.
The new online system automatically sends these so-called "shake maps" within five minutes of a quake to people like Robert Garrott of the Los Angeles County Office of Emergency Management. The color-coded map becomes a quick visual guide for where to best send crews to assess the damage.
|
|
The "Did You Feel It?" map of the 1994 Northridge quake, created from data provided by answers to an online questionnaire.
Graphic courtesy TriNet
enlarge image
|
"Shake maps" are also available on the Internet within minutes. That's helpful both to those near the quake, Wald tells Bowers, and those outside California watching scenes of the worst destruction on television.
The U.S.G.S. has another Internet innovation for U.S. regions that aren't dotted with sensors like California, but still feel earthquakes from time to time. A simple "Did You Feel It?" questionnaire about the effects of the quake helps map the quake's intensity.
Depending on how many people respond, the data can help create a remarkably detailed ZIP code map of the shaking.
Browse more NPR stories on earthquakes.
Other Resources
• Real-time shaking maps from the U.S. Geological Survey.
• TriNet is a joint online project of the CalTech Seismological Laboratory, the U.S. Geological Survey Earthquake Hazards Program and the California Geogogical Survey.
• Did you feel it? Fill out an online survey form.
|
