Scientists Accurately Predict Size and Location of 2012 Costa Rica Earthquake

Could there be a way to predict earthquakes? In the case of the 2012 Costa Rica earthquake there was. Scientists using GPS to study changes in Earth's shape accurately forecasted the size and location of the magnitude 7.6 Nicoya earthquake.

The Nicoya Peninsula in Costa Rica is one of the few areas on Earth where land sits on top of a portion of a subduction zone where Earth's greatest earthquakes take place. This makes Costa Rica the perfect place for learning about how large earthquakes rupture. Because earthquakes greater than magnitude 7.5 have struck this region about every 50 years, researchers prepared for this particular earthquake through a number of geophysical studies.

Subduction zones are areas where one tectonic plate is forced under another one. The collision of tectonic plates during this process can unleash earthquakes and tsunamis. For example, the devastating 9.0 earthquake off of the coast of Japan in 2011 was due to one of these subduction zones.

"The Nicoya Peninsula is an idea natural lab for studying these events, because the coastline geometry uniquely allows us to get our equipment close to the zone of active strain accumulation," said Susan Schwartz, one of the researchers, in a news release.

Using detailed geophysical observations of this area, the researchers created an image of where the faults had locked. This allowed them to describe a particular locked patch with the clearest potential for the next large earthquake in the region only a few months before the actual earthquake. By looking at the past earthquake in 1950, the scientists were able to determine that enough energy was present to create a 7.8 magnitude earthquake. Considering that quakes occur in the region ever 50 years, they predicted the next one would occur around 2000, give or take 20 years.

"Nicoya is the only place on Earth where we've actually been able to get a very accurate image of the locked patch because it occurs directly under land," said Andrew Newman, one of the researchers, in a news release. "If we really want to understand the seismic potential for most of the world, we have to go offshore."

The findings reveal a bit more about these large earthquakes and could pave the way for future studies in different areas. The scientists hope that their work in Nicoya will be a driver for geodetic studies on the seafloor to observe Earth deformation.

The findings are published in the journal Nature Geoscience.