How did scientist use to predict chileas earthquake?

Answer 1

Ruegg and coworkers published a paper in "Physics of the Earth and Planetary Interiors" (Ruegg JC, 175:78-85, 2009). The team made observations in a range from 1996 to 2002, focusing in the area from Constitución to Concepción, since no major earthquakes occurred in that space since 1835 (described by Darwin). They measured the displacement of the plate (more exactly, the velocity of the movement). The results (at a big glance, since I am not a geologist) showed that coastal regions had a higher velocity compared with regions in the Andes area. Assuming that no major earthquakes released the accumulated force since 1835, a deficit of horizontal displacement of 10 m will have accumulated. To Ruegg and coworkers, this could mean, in a worst case scenario, "that the southern part of the Concepción-Constitución gap has accumulated a slip deficit that is large enough to produce a very large earthquake of about Mw = 8.0-8.5". This February 27, at 3:34 am (Chile's time), an earthquake with a magnitude of 8.8 in Ritcher scale occurred in a site very close to Cobquecura, located between Concepción and Constitución (see map below). The plates moved 8 m, and since Ruegg and coworkers calculated a 10 m of slip deficit, either the calculations are overestimated or the earthquake should have been even worse.Nonetheless, the prediction of Ruegg and his team is shocking. They were right about the epicenter and magnitude. The final phrase of the abstract is: "… in a worst case scenario, the area already has a potential for an earthquake of magnitude as large as 8-8.5, should it happen in the near future".

Conclusions:

An obvious conclusion for our country, Chile, is the following: scientific observations can assist to make predictions about the most probable sites of a future earthquake, including information about the magnitude. Ideally, a global network across the identified seismic gaps in Chile (one at the north, one near to Valparaiso, one located between Concepción-Constitución and one near to Valdivia, epicenter of the greatest earthquake in the last 200 years) and some other regions , could help to be better prepared for a new earthquake. I don't know of such an approach is being used in other seismic regions on Earth.