Why Chile’s Huge Earthquake Wasn’t Much Worse

We actually can learn from the past
Map of Chile Earthquakes
A map showing historic earthquakes in Chile. Yellow dots show earthquakes larger than a magnitude 8.3, like the one that happened on September 16. USGS

The quake that struck just off the coast of Chile last night was huge by any standard. It measured a magnitude 8.3, shaking considerably more than the 7.8 magnitude earthquake that devastated Nepal earlier this year.

So why did over 8,000 people die in the Nepal quake and its aftershocks while only an estimated 8 people died in Chile?

There are a lot of factors that made this particular natural disaster less disastrous, including its location. While the initial quake in Nepal occurred around 50 miles outside the heavily populated capital of Kathmandu, the Chilean quake occurred over 140 miles northwest of the capital of Santiago, off the coast. Less shaking in a major population center definitely helped limit casualties. But Chile also fared so well in this latest disaster because they were ready for it.

“Earthquake impact is a little like real estate: What matters is location, location, location,” said Susan Hough, a geophysicist with the U.S. Geological Survey told the Associated Press. “But it is true that preparedness and risk reduction in Chile is ahead of that in much of the world, and that makes a difference.”

Tectonic Plates

Chile is located at the intersection of two tectonic plates, areas of the Earth’s surface that underlay all the continents and oceans on the planet. Chile is located on the South American plate, where a small plate called the Nazca plate, located under the Pacific ocean, is sliding under the South American plate. That motion is pushing up the Andes mountains, and for the most part moves under the South American plate slowly, moving around 3 inches every year. But occasionally, large areas of the Nazca plate slip, moving quickly and dramatically, and causing huge earthquakes. The largest earthquake ever recorded, a magnitude 9.5 happened in Chile in 1960, and more recently a huge 8.8 magnitude earthquake occurred in 2010, killing over 500 people when a tsunami caused by the Earth’s shaking slammed into shore.

This time, when the shaking went on for three minutes, the Chilean people knew exactly what to do, thanks to extensive educational campaigns aimed at teaching people the proper steps to take in a disaster. The government swiftly evacuated one million people from the coast to higher ground, worried that a tsunami might hit. Localized tsunamis higher than 15 feet did strike one part of the coast, but for the most part, the waves were small.

Also because of Chile’s past experience with earthquakes, building codes are strict, so even though a few buildings collapsed and many were damaged, the devastation was far less than other areas like Nepal, where many areas were reduced to rubble and limited infrastructure made recovery difficult. After the 2010 quake, the Chilean government funded and deployed a massive network of seismic sensors, able to detect earthquakes and tsunamis as they happen, and issue warnings to the general population.

Other areas of the world are also working on expanding such networks to give populations more time to react, and hopefully prevent more deaths. In the United States, researchers are building a prototype earthquake early warning system. We’re never going to live in a world without earthquakes. The best we can hope for is to be ready for them.