Residents of the Seattle-Tacoma, Washington, region were rocked on
February 28 (yesterday) by a magnitude 6.8 earthquake that sent out
shockwaves felt as far away as Salt Lake City, Utah. Although this is
considered to be a major magnitude earthquake, and there was widespread
structural damage reported throughout the Seattle region, the severity
of the impact is considered to be somewhat modest. According to the
United States Geological Survey (USGS), the quake's epicenter was about
30 miles (48 km) below the surface. That fact combined with improved
building design codes helped minimize the property damage. For
instance, the Space NeedleSeattle's renowned landmarkwas
designed to sway in high winds rather than stand rigid. Dozens of
tourists rode out the earthquake atop the 600-foot-tall (182 m) tower.
The epicenter of the quake was somewhere between Washington's capital
city of Olympia and Tacoma. Tacoma is pictured in this false-color
composite image acquired by the Advanced Spaceborne Thermal Emission and
Reflection Radiometer (ASTER), flying aboard NASA's Terra satellite, on June 28,2000. In
this scene, the dark and light red pixels show more or less vegetation
on the surface. The light blue and grey pixels show areas of human
development. The dark pixels in the upper lefthand corner of the image
represent the East Passage leading up into the Puget sound, in which the
southern shoreline of Vashon Island can be seen. Just east of Puget
Sound, you can see the Sea-Tac Airport.
The two graphics beneath the ASTER image provide a three-dimensional
perspective on the earthquake's epicenter (orange ball), relative to the
surface. The blue contour lines represent geopolitical boundaries on
the surface. These graphics were generated using seismic data compiled
by Paul Morin at the University of Minnesota.
Images courtesy NASA/GSFC/MITI/ERSDAC/JAROS,and U.S./Japan ASTER Science Team and
Paul Morin, University of Minnesota.