Tuesday, September 29, 2009

Magnitude 8.0 quake in Samoa

A magnitude 8.0 quake has struck in the Samoa Islands of the Pacific. Andrew Alden at About.com is on top of this with some details here. The official USGS report is here. I only want to add that my cheap little classroom seismometer is still going off-scale more than an hour after the event. It doesn't mean that the ground is still heaving in Samoa, but instead is showing that the entire earth is reverberating as the waves pass through the entire planet, reflecting and refracting off the interior boundary layers and discontinuities. One might compare it to the gonging of a bell (the "earthquake") and the ringing tones that follow for a few moments.

You can check out the current shaking as it is recorded in California right here. Click on any of the stations to see the wave activity.
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