What Else Should I Know?

Earthquake Information on the Web

Earthquake Information on the Web

After an earthquake, knowing more about what just happened can reduce fears and help you understand what to expect next. Online earthquake information products include:

Location and magnitude of recent earthquakes

Within 1 to 2 minutes of an earthquake, its location and magnitude are available at several Web sites, including
earthquake.usgs.gov and quake.usgs.gov/recenteqs/latest.htm.


Within 5 to 10 minutes of most felt earthquakes (magnitude 3.5 and greater) in the Bay Area, a ShakeMap is posted on the Web. This map shows the range of shaking intensities across a region. Every quake has only a single magnitude, but it produces a range of shaking intensity values over the area in which it is felt.

ShakeMaps use data from seismic instruments to provide a rapid picture of where the strongest shaking occurred. These maps help to identify areas where a quakes impact is greatest and are used by emergency managers to speed disaster response. ShakeMaps are available at www.cisn.org/shakemap.html or earthquake.usgs.gov/shakemap/.

"Did You Feel It?"—Tell us what you felt!

Personal experiences of the effects of an earthquake are very valuable to scientists. When you have felt a quake, please report your observations by using a quick survey found on the U.S. Geological Survey "Did You Feel It?" Web site.

When you fill out this online survey, your observations of actual damage and shaking are combined with those of thousands of other people. The quakes shaking intensities, derived from these observations, are displayed by ZIP code on a "Community Internet Intensity Map."

Who monitors California's earthquakes?

Earthquake monitoring for California is done by the California Integrated Seismic Network (CISN), a partnership among the U.S. Geological Survey (USGS), University of California Berkeley, Caltech, the California Geological Survey, and the Governors Office of Emergency Services. CISN is part of a USGS national seismic-monitoring program called the Advanced National Seismic System (ANSS).

For more information go to www.cisn.org or www.anss.org

Map of recent earthquakes in the San Francisco Bay region

Map of recent earthquakes in the San Francisco Bay region, just after the September 3, 2000 magnitude 5.2 Yountville (Napa) earthquake.

ShakeMap for the 2000 magnitude 5.2 Yountville (Napa) earthquake

"ShakeMap" for the 2000 magnitude 5.2 Yountville (Napa) earthquake. The strongest shaking was not centered on the quake, but to the south in the soft soils of the Napa River Valley.

Community Internet Intensity Map

Community Internet Intensity Map ("Did You Feel It?") for the 2000 magnitude 5.2 Yountville (Napa) earthquake. More than 7,700 people reported their observations on this quake online.