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Subject: Earthquake Conversations
From: "Bob Hancock" robert.hancock@...........
Date: Wed, 25 Dec 2002 18:57:20 -0500

On pages 72 - 79, in the January 2003 edition of Scientific American, there
is an article on earthquakes, and some insight into earthquake prediction,
titled Earthquake Conversations.  Copied below is the teaser contained on
their web site.  The author is a PhD geophysicist with the USGS Hazards Team
in Menlo Park, CA.  You can download the article from the archives of the
Scientific American web site for a fee, or buy the magazine.

* * * * * * * * *

Earthquake Conversations

Contrary to prevailing wisdom, large earthquakes can interact in unexpected
ways. This exciting discovery could dramatically improve scientists' ability
to pinpoint future shocks

By Ross S. Stein

For decades, earthquake experts dreamed of being able to divine the time and
place of the world's next disastrous shock. But by the early 1990s the
behavior of quake-prone faults had proved so complex that they were forced
to conclude that the planet's largest tremors are isolated, random and
utterly unpredictable. Most seismologists now assume that once a major
earthquake and its expected aftershocks do their damage, the fault will
remain quiet until stresses in the earth's crust have time to rebuild,
typically over hundreds or thousands of years. A recent discovery-that
earthquakes interact in ways never before imagined-- is beginning to
overturn that assumption.

This insight corroborates the idea that a major shock relieves stress-and
thus the likelihood of a second major tremor-- in some areas. But it also
suggests that the probability of a succeeding earthquake elsewhere along the
fault or on a nearby fault can actually jump by as much as a factor of
three. To the people who must stand ready to provide emergency services or
to those who set prices for insurance premiums, these refined predictions
can be critical in determining which of their constituents are most
vulnerable....continued at the Scientific American Archive


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