Keeping an eye on geological faults can be useful even long after they convulse in a great earthquake. By watching a Turkish fault after a deadly 1999 quake, geologists have pieced together a detailed picture of creeping fault movement after a big shake-up.
The magnitude 7.4 Izmit earthquake broke part of the North Anatolian fault, killing more than 17,000 people. In the years since, scientists have found, the two sides of the fault have started to creep past each other again at rates up to about 27 millimeters annually, most likely building up stress to the west near Istanbul.