US Geological Survey
Fact Sheet 014-03
"SHAKEMAP" AND THE ADVANCED NATIONAL SEISMIC SYSTEM
shake map showing intensity of shaking for the November 3, 2002, Denali Fault earthquake in Alaska

A "ShakeMap" portraying shaking intensities during the November 3, 2002, Denali Fault earthquake (above) was released a few days after the quake by the U.S. Geological Survey (USGS) and the Alaska Earthquake Information Center (AEIC) at the University of Alaska Fairbanks. This ShakeMap, the first produced for Alaska, was created using data from about 50 seismic instruments across the State, including some managed by the Alyeska Pipeline Service Company at pump stations along the Trans-Alaska Oil Pipeline.

Because of the vast area shaken by the magnitude 7.9 quake and the relatively small number of seismic recordings from near the fault (two-thirds of the data were from Anchorage), this ShakeMap offers only a generalized picture of the intensity of the ground shaking. Nonetheless, this map shows a pattern for the Denali Fault region remarkably similar to that on a map of shaking hazard for Alaska that was produced by USGS scientists in 1999 (shown below).

One purpose of ShakeMaps is to provide rapid information to aid emergency managers in responding to a quake. Another purpose of ShakeMaps is to reveal local variations in shaking that engineers can use to better design buildings to withstand earthquakes. To realize both these goals, the USGS and its cooperators have begun building a dense nationwide network, called the Advanced National Seismic System (ANSS), to consist of at least 7,000 sophisticated shaking monitors. These instruments are being placed both on the ground and in buildings. Because building failures are what kill the most people in earthquakes, the data that can be provided by ANSS will be crucial in saving lives in future quakes.

a seismic hazard map for Alaska created in 1999
USGS Seismic Hazard Map for Alaska
(areas of highest hazard in red)
1999
photograph of a 14-story building in Anchorage that was monitored during the 2002 Denali Fault earthquake; the records of the monitoring will help engineers improve building design a seismic record from the roof of a 14-story building in Anchorage; such records will help engineers improve building designs
During the fall 2002 magnitude 7.9 Alaska earthquake, shaking monitors in this 14-story building in Anchorage recorded complex twisting and swaying motions. When analyzed, these records (including that shown above taken on the building's roof) will help engineers improve building designs.

 

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