Earthquake Conversations; Our Ever Changing Earth; Special Editions; by Ross S. Stein; 8 Page(s)

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 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.