11 Sept
When a segment of a major fault line goes quiet, it can mean one of two things: The “seismic gap” may simply be inactive—the result of two tectonic plates placidly gliding past each other—or the segment may be a source of potential earthquakes, quietly building tension over decades until an inevitable seismic release.
Researchers from Massachusetts Institute of Technology (MIT) and Turkey have found evidence for both types of behavior on different segments of the North Anatolian Fault—one of the most energetic earthquake zones in the world. The fault, similar in scale to California’s San Andreas Fault, stretches for about 745 miles across northern Turkey and into the Aegean Sea.
The researchers analyzed 20 years of GPS data along the fault, and determined that the next large earthquake to strike the region will likely occur along a seismic gap beneath the Sea of Marmara, some five miles west of Istanbul. In contrast, the western segment of the seismic gap appears to be moving without producing large earthquakes.
“Istanbul is a large city, and many of the buildings are very old and not built to the highest modern standards compared to, say, southern California,” says Michael Floyd, a research scientist in MIT’s Dept. of Earth, Atmospheric and Planetary Sciences. “From an earthquake scientist’s perspective, this is a hotspot for potential seismic hazards.”
Although it’s impossible to pinpoint when such a quake might occur, Floyd says this one could be powerful—on the order of a magnitude 7 temblor, or stronger.
