Quotes of the Day

The earthquake that tore through eastern Turkey on Oct. 23 was as inevitable as it was shocking. It was inevitable because Turkey lies in one of the world's most active seismic zones, crossed by numerous fault lines. As much as in Northern California or Japan, earthquakes are a fact of geological life in Turkey. But it was shocking because so many people — at least 279, many in the city of Ercis — died in the 7.2 temblor. It was a strong quake, but hardly a monster like the 9.0-scale disaster that hit northern Japan this spring. Yet scores of multistory buildings simply collapsed when the latest quake hit, burying hundreds of Turks.

"The buildings around us, the coffee house all went down so quickly," 42-year-old Abubekir Acar told the Associated Press. "For a while, we could not see anything — everywhere was covered in dust. Then we heard screams and pulled out anyone we could reach."

The quake was yet another reminder that the damage and death toll from a natural disaster often has much less to do with the strength of a quake or a storm than it does with the preparations — or lack thereof — among victims. For earthquakes — which still can't be predicted, and may never be — the best preparation is strong building design. Turkey is home to some sturdy, earthquake-ready architecture that's by no means the rule there. Buildings made of unreinforced brick simply pancaked, turning schools and apartment buildings into tombs. "In recent earthquakes, buildings have acted as weapons of mass destruction," the seismologist Roger Bilham of the University of Colorado wrote in a Nature article last year.

That's a horrifying thought, but what's really scary is that the threat from quakes like the one that struck eastern Turkey is only increasing. It's not that there's any evidence that earthquakes are becoming stronger or more frequent. Instead, it's us: global population is growing, set to pass 7 billion at the end of the month, and we're concentrating in megacities that are orders of magnitude bigger than any human settlements in the past. There are now more than 380 urban areas with at least 1 million people, and according to Bilham's work, more than 400 million people live in cities that face significant seismic risk.

Some of those cities you've heard of, like San Francisco, Los Angeles or Tokyo — all of which have suffered major quakes over the past several decades. But the great wealth of the developed nations mostly — but not always — means better building designs. San Francisco may sit near the powerful San Andreas Fault, but years of experience with quakes mean that not just buildings but citizens are as ready as they can be for the Big One. Ditto Tokyo; strict building codes in Japan kept the death toll from this spring's quake and tsunami much lower than it might have been.

The real danger is in poor but rapidly growing cities in the developing world. Much of the population growth in the next several decades will occur in South Asia and sub-Saharan Africa — and in the slums of emerging megacities. By midcentury, most of the biggest cities on the planet will be in the developing world — places like New Delhi, Dhaka or Karachi. That's a lot of poor people living in densely packed conditions that are not built for major quakes — a recipe for catastrophically high death tolls.

One way to improve resilience is simply through economic development — a richer population is in general better able to deal with disasters. But being better off isn't enough, as Turkey illustrated. And you don't have to be wealthy to be ready for a temblor. Civil engineers like Santiago Pujol of Purdue University have designed structures made of cheap materials like straw, clay and gravel that won't collapse in the event of a quake. And when buildings made of relatively light materials do collapse, they cause fewer deaths. Groups like GeoHazards International have sent seismologists and architects to help leaders in cities in the developing world shore up these and other defenses against natural disasters.

With earthquakes — as with so many other problems — we rarely give prevention enough emphasis until it's too late. That needs to change. Over the next half-century, as the world adds 2 billion or more people, it will construct as many as 1 billion housing units. Earthquakes will happen — we can't stop them. How many people will die needlessly in a temblor, however, will depend on how strong those buildings are — and that much we can control.

• Bryan Walsh
• Turkey's recent earthquake is a reminder that while we can't predict or control earthquakes, we can be ready for them