What Turkey’s earthquake tells us about the science of seismic forecasting

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Two decades ago, John McCloskey drew a red line on a map of southeastern Turkey to pinpoint where a large earthquake would probably strike. The only question was when.

The answer came last month, when a magnitude-7.8 shock hit the precise location that McCloskey and his team had identified. It struck at 4.17 a.m. local time on 6 February, when most people were asleep, and killed more than 50,000 residents in Turkey and neighbouring Syria.

McCloskey’s work shows both the promise — and limitations — of the science of earthquake forecasting. Although geologists have long attempted to provide warnings of the location, magnitude and exact time of future quakes, decades of research have shown that it’s probably impossible to predict when a geological fault will start to shake. “When you try to winnow it down to know what’s going to happen next, it tends to be a lesson in humility,” says Susan Hough, a geophysicist in the Earthquake Hazards Program at the United States Geological Survey (USGS). “The real focus in most of the world is not on prediction, but on assessing the hazard and the long-term rates of earthquakes.”

Today, researchers work on forecasting: identifying which fault segments are most dangerous and what size earthquakes they are expected to produce. Armed with that knowledge, policymakers can take steps to reduce death and destruction by, for example, requiring better building practices or urging local residents to prepare. Some regions of Japan, the United States and Turkey have developed early-warning systems that alert residents when an earthquake has started nearby. “In principle, you can get rid of seismic risk,” McCloskey says.

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