California Earthquake Risk Paper

California Quake Risk

In a recent study done by the seismologists at the University of California, Berkeley it has been discovered that the faults that currently run through California may be more dangerous and a bigger threat than everyone originally thought. Both of the faults are part of the North American Plate and run parallel to the San Andres Fault. The faults that are being researched are the Calaveras Fault and the Hayward Fault and the purpose of the research was to see if the two faults could actually have a connection and a threat.

A little bit of background on the faults and the power that the earthquakes produced by the faults in the past are described a little bit in the article. According to the article the maximum earthquake on a fault that can occur is based on its length so originally the threat from the two different faults was based on a separate basis. A U.S. Geological Survey recently estimated that there is roughly a 14.3 percent likelihood that a 6.7 or greater earthquake will most likely occur on the Hayward Fault in the next 30 years. On the other side the Calaveras Fault is estimated to have an earthquake as high as 7.4 on the Richter scale. Both of these estimations were based on the fact that each of the faults are an independent system so what if they are connected?

According to the seismologists from the University that did the study the question of whether the two faults are connected has been speculated for a long time. In the study it was found that the creep of the Hayward Fault did not end where they thought and that the fault continues 15 kilometers longer than they thought. This means that the trace of the Hayward fault meets the trace of the Calaveras Fault and also that micro-earthquakes merge 3-5 kilometers below the ground from the faults. Since both are strike-slip faults it was found that the Hayward Fault dips at an angle where it meets the Calaveras fault and therefore a major earthquake could be caused by the two faults together. The 70 kilometer Hayward fault which was already considered one of the most dangerous faults in the country is not turning out to be even more dangerous than people thought. Based on the research the two faults together could produce and release energy up to 2.5 times greater than originally thought. This would be devastating to the communities in the area. It is estimated that the Hayward fault only moves about 10 mm underground each year and the earthquakes result from the surface suddenly catching up with the underground long-term movement so the seismologists are now working to predict how soon these two faults could cause a massive earthquake together.