Chile quake: This was big but a bigger one awaits, scientist says - CNN

• Geologists say an even larger quake in the region is lurking


• Scientist: "We do not know when it's going to occur"


• Chile has seen no shortage of seismic activity in recent years

(CNN) -- This one was big but it's not the Big One.

An 8.2-magnitude earthquake struck off the coast of northern Chile Tuesday night, triggering small landslides, setting off a tsunami and killing at least five people.

But geologists say an even larger quake in the region is lurking.

People embrace on the upper floor of an apartment building in Iquique, Chile, where they gathered after an 8.2-magnitude earthquake triggered a tsunami off the town's coast on Tuesday, April 1.

People evacuate Iquique on April 1. The earthquake generated tsunami waves of more than 6 feet, according to the Pacific Tsunami Watch Center.

People take to the streets after the earthquake, which hit at 6:46 p.m. local time.

A fire burns at a restaurant in Iquique after the earthquake on April 1.

A woman and her dog stand against a wall in Iquique on April 1. Chile is on the so-called "Ring of Fire," an arc of volcanoes and fault lines circling the Pacific Basic that is prone to frequent earthquakes and volcanic eruptions.

Girls wait in a hallway before evacuating Iquique on April 1. A tsunami warning was in effect for Chile, Peru, Ecuador, Colombia and Panama.

Iquique residents wait outside on April 1. Chilean authorities asked people along the coast to evacuate.

Iquique residents wait in a parking garage after the earthquake on April 1.

Residents in Iquique prepare to evacuate on April 1.

Earthquake off Chilean coast

Earthquake off Chilean coast

Earthquake off Chilean coast

Earthquake off Chilean coast

Earthquake off Chilean coast

Earthquake off Chilean coast

Earthquake off Chilean coast

Earthquake off Chilean coast

Earthquake off Chilean coast

Photos: Earthquake off Chilean coast

"This magnitude 8.2 is not the large earthquake that we were expecting in this area," said Mark Simons, a geophysicist at Caltech in Pasadena, California. "We're expecting a potentially even larger earthquake."

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"We do not know when it's going to occur," he said.

Here's why:

Chile sits on an arc of volcanos and fault lines circling the Pacific Ocean known as the "Ring of Fire." This area sees frequent earthquakes and volcanic eruptions.

The country itself has seen no shortage of seismic activity in recent years.

Since 1973, Chile has had more than a dozen quakes of magnitude-7.0 and above.

In 2010, about 500 people died when an 8.8-magnitude earthquake hit. That quake was so violent, it moved one whole city about 10 feet west.

Simons says Tuesday's quake is of interest because the fault line along Chile's coast has constantly shifted during the last 140 years.

In recent weeks, this area has seen a cluster of activity-- something like 50 to 100 smaller quakes.

Then, late last month, a 6.7 and a 6.1 magnitude quake struck.

When quakes happen, the surface ruptures. The two sides of the fault slip past each other.

But the area to the north and south of Tuesday's quake "did not rupture in this event," Simons said. And it's "still an area that hasn't ruptured in 140-odd years."

Given that it's an area of frequent quakes, and frequent ruptures, it may only be a matter of time.

"We expect another 8.8-8.9 earthquake here sometime in the future," Simons said.

The good news? "It may not occur for many, many years."

READ: Powerful earthquake strikes off Chile, triggers tsunami

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