Science Frontiers ONLINE No. 86: Mar-Apr 1993 Issue Contents

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Geysers As Detectors Of Distant Earthquakes

June 1992. Landers, California. An earthquake of magnitude 7.5 shook this small town. In apparent sympathy with the Landers disturbance, seismic activity appeared from one end of California to the other, as well as in Nevada, Utah, Idaho, and Wyoming.

The Landers quake stimulated unusual seismicity in the solid black areas.

Yellowstone Park, Wyoming. Here, 1100 kilometers from Landers, the geyser Echinus, which had been erupting on a regular schedule of every 56 minutes, went berserk. It didn't settle down for 34 hours. Geyser eruptions are frequently disturbed by nearby quakes, but Landers was hardly nearby!

The seismology community.

"Those distant shocks have startled seismologists as well as ordinary residents. Conventional thinking, at least among U.S. researchers, holds that stress generated when a fault slips in an earthquake peters out within a distance equal to a couple of times the length of the ruptured fault. For Landers, where about 70 kilometers of fault ruptured, this would amount to only about onetenth of the observed reach."

Seismologists are now searching for ways to account for these unexpectedly far-reaching effects.

(Monastersky, Richard; "Yellowstone Geyser Shows Quake Effect," Science News, 142:428, 1992. Also: Kerr, Richard A.; "Landers Quake's Long Reach Is Shaking Up Seismologists," Science, 259:29, 1993.)

From Science Frontiers #86, MAR-APR 1993. � 1993-2000 William R. Corliss

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