Rocks' Balancing Act Gives New Insight Into Earthquakes
Conventional wisdom in a large earthquake is that large unstable objects tend to fall down in the midst of all the shaking. But not always. In one area of California, close to the famous San Andreas fault, there are a few delicate geological formations that have weathered intense historical earthquakes without falling down. These 'precariously balanced rocks,' known as PBR's (no relation to the beer) have been balanced for 10,000 years, a span of time during which there have been 50-100 large earthquakes in the area. So why are they still standing? In a new paper published in Seismological Research Letters researchers found that interactions between two faults, the San Andreas and the San Jacinto may be the answer to the mystery. “It was a real scientific puzzle, a real head-scratcher,” author Lisa Grant Ludwig said in a statement. “How can you have these rocks right next to...