Zero Gravity: The Lighter Side of Science
Rattle in Seattle Creates Earthquake Art
The Earthquake Rose. Scientists believe the squiggly lines at the center of the pattern were formed during the quake's most intense trembles.
Two weeks before the onset of the APS March Meeting in Seattle, the city was rocked by a magnitude 6.8 earthquake, cracking sidewalks, toppling building facades, and even cracking the capital dome in Olympia. Fortunately, major structural damage was less than expected, since the quake was located about 30 miles below Earth's surface. The meeting took place without a hitch. But further north, in the sleepy settlement of Port Townsend, Mother Nature offered striking visual evidence that earthquakes have an artistic bent as well.
A local shop called Mind Over Matter displayed a sand-tracing pendulum, featuring a pointed weight at the end of a long wire suspended over a tray of sand. The vibrations of the quake produced an intricate, rose-like shape in the sand. "You never think about an earthquake as being artistic - it's violent and destructive," Norman MacLeod, president of Gaelic Wolf Consulting in Port Townsend, told ABC News. "But in the middle of all that chaos, this fine, delicate artwork was created."
Images of the unusual pendulum pattern were distributed over the Internet, and quickly spread around the world. MacLeod, who posted the images on his Web site (http://www.gaelwolf.com/pendulum.html), has received thousands of letters from people theorizing about what the shape might mean: the eye of Poseidon, a rose, or even (for conspiracy buffs) a recording of a top secret government weapon designed to trigger earthquakes.
Seismologists are a bit more circumspect in their conclusions. "The pattern shows the three-dimensional pattern of the quake. It's a nice little seismogram that helps people understand how the ground was moving at the time of the quake," says Bill Steele, a seismologist at the University of Washington. Modern seismograms record the north-south, east-west and vertical shakings of a quake. The information is then fed into a computer that creates a three-dimensional reading.
While the sand carved by the pendulum offers a less precise reading of the multidirectional tremors of the quake, it preserves two features of the earthquake waves in particular. The "flower" in the center records the surface movements associated with the higher frequency waves that arrived first. The outer larger amplitude oscillations record the lower frequency waves that arrived later.
Sadly, the Earthquake Rose is no more. Shop owner Jason Ward had intended to take a mold of the pattern. But before this could be done, his three-year-old son accidentally kicked the pendulum - and erased the sand's design. At least Ward still has the photographs.
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