Nature S Earthquake Forecaster
After lowering instruments half a mile into two deep drilled-holes alongside the San Andreas fault in Parkfield, CA, and leaving them there for two one-month stints in 2005 and 2006, researchers from Rice University, the Carnegie Institution of Washington, and the Lawrence Berkeley National Laboratory took measurements of the density of small cracks in the rock. Two distinct changes preceded and lasted through two separate earthquakes—one a magnitude 1, and one a magnitude 3—by two and ten and a half hours respectively....