How the Chile Earthquake Went Nuclear

If you want to grow a truly massive earthquake, you've got to give it space. Scientists have known this basic fact for years -- more powerful earthquakes ramp up the shaking by breaking along huge stretches of faults. The magnitude 7.0 earthquake just outside Port-Au-Prince in January unzipped a 65-kilometer (40.4-mile) long section of the Enriquillo-Plantain Garden Fault. Despite the unfathomable devastation it caused, it was a second-tier quake at best.

If you want to grow a truly massive earthquake, you've got to give it space.

Scientists have known this basic fact for years -- more powerful earthquakes ramp up the shaking by breaking along huge stretches of faults. The magnitude 7.0 earthquake just outside Port-Au-Prince in January unzipped a 65-kilometer (40.4-mile) long section of the Enriquillo-Plantain Garden Fault. Despite the unfathomable devastation it caused, it was a second-tier quake at best.

As has been widely reported, the Chile quake was a megathrust earthquake, the largest class of tremor we know of. At magnitude 8.8, it was over 500 times more powerful than the Haiti quake.

In a preliminary analysis of data from the quake, researchers from the GFZ German Research Centre for Geosciences are starting to unravel how it got to be such a monster. Turns out, it was a chain reaction of sorts. In the first minute, activity was confined to the area around the epicenter of the quake, about 200 miles south of Santiago. In the second minute, it tore north toward Santiago and stopped, before rearing its ugly head again south of the epicenter and racing toward the city of Concepcion.

 



As the animation shows, the quake was a string of different activity all popping off at roughly the same time. How this happens is a mystery of science. Stress builds ever so slowly, gradually for centuries and then -- Blam! -- a tear in the crust forms and propagates as fast as a bullet shot from a gun. In the latest Chile quake, a ribbon of Earth 700 kilometers (435 miles) long was shredded in a matter of about two minutes.

It's like nuclear fission: if just one atom goes, no big deal. But string enough together and suddenly...mushroom cloud.

Studying huge, sprawling forces operating at such high speeds tens of miles underground is tough work, which is what makes a study like this so useful. If scientists can figure out how ruptures propagate through faults to form giant quakes, they may be able to predict the impending final chapter in this round of Chilean megathrust quakes, as well as others around the world.

 

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