Chile has been expecting a very large earthquake for the past two decades, as its tectonic plates were strained. However, the earthquake the region received in April was not enough to remove the threat of a massively destructive quake in the future, scientists say. They warn the region to expect a magnitude 9 earthquake sometime in the near future.
Chile is a very earthquake-prone country, located on the edge of the South American plate and the Nazca plate. The two plates touch each other through a force called subduction. The two plates can cause massive earthquakes. The largest earthquake ever recorded in the world occurred in Chile, a 9.5-magnitude earthquake that was responsible for the deaths of 1,655 people and destroyed the homes of another 2 million.
Scientists are expecting another high-magnitude earthquake in northern Chile, where the last major quake occurred in 1877. That earthquake was an 8.8-magnitude quake that gave rise to a 79-foot tsunami, creating a wave of death that killed people as far off as Japan and Hawaii.
After studying the past 500 years of earthquakes in Chile, seismologists have suggested that the region should expect a massive earthquake every 111 years. That means that northern Chile should be expecting another major earthquake very soon.
The pending stress was not relieved by an 8.2-magnitude earthquake that the region felt on April 1 of this year, scientists say. The April quake set off a 6.5-foot tsunami, and killed six people, as well as racking up approximately $100 million in damages.
"Generally after earthquakes this large, people close to the event think it unlikely that they could experience other similar events in the near future," says Gavin Hayes. However, the region's tectonic plates have more strain that was not relieved by even an earthquake of that magnitude, Hayes says. Hayes is a geophysicist working at the U.S. Geological Survey. He was the lead author on one of the two studies about the pending Chilean earthquake in the journal Nature.
Hayes and his research group studied the April earthquake in Chile, and the foreshocks that came before it. The increase in activity in the region began in August 2013. Since then, earthquakes of magnitude-3.5 or greater grew 950 percent more frequent. However, the total energy of the earthquakes added up to only a magnitude-8.3 earthquake, much less than the 1877 earthquake.
"The subduction zone adjacent to northern Chile has not released all of its accumulated strain and thus could host events of a similar size, or larger in size, to what we have just experienced," Hayes says.