14 DAY TRIAL // We do not know if Superman will be around to save the situation, but by 2037, a megaquake could strike California. A new three-year analysis made by the U.S. Geological Survey (USGS), Southern California Earthquake Center (SCEC), and California Geological Survey shows the existence of a 99.7% chance that a quake with the magnitude of 6.7 or larger will occur in the next three decades, based on newly available information. This will occur rather in southern California than in northern California (97% versus 93%).
The last Californian megaquake, the 1994 Northridge disaster, left 72 dead, 9,000 injured and brought damages of $25 billion.
The report "basically guarantees it's going to happen," said lead author Ned Field, a USGS seismologist based in Pasadena.
California is known as one of the world's most seismically active areas. Its territory comprises 300 faults, located between the Pacific tectonic plate and the North American plate. Such a web of faults generates annually 10,000 quakes only in southern California, but the majority is too small to be felt by humans.
A 2003 report forecast that the San Francisco Bay Area presented a 62% chance of being hit by a magnitude 6.7 quake by 2032. The new analyses boosted this chance to 63% by 2037. It is impossible to say precisely where the quake will take place or when. This is just a warning signal.
"A big earthquake can happen tomorrow or it can happen ten years from now," said co-author Tom Jordan, director of SCEC headquartered at the University of Southern California.
The study is a first step enabling the researchers to make hazard maps revealing the power of possible earthquakes in a particular zone. This could also be used for updating building norms, earthquake insurance rates and emergency plans.
The most dangerous area is in the southern part of the San Andreas fault (from Parkfield to the Salton Sea). There's a 59% probability that a quake with the magnitude around 7 or higher will occur in these areas, compared to a 21% probability for the northern section, responsible for the famous 1906 San Francisco earthquake. The researchers calculated this higher probability based on the fact that the southern part has not shaken for over three centuries. The Hayward (in the San Francisco Bay Area) and San Jacinto (in the San Bernardino area) faults have a 31% chance of provoking a megaquake.