A NEW study has revealed that earthquakes in California are originating from much deeper underground than it was thought, meaning that they will be even more devastating than previously feared. Californians are currently on a knife-edge as experts believe that they could be close to a devastating earthquake when the San Andreas fault finally gives. Seismologists thought that powerful earthquakes had stemmed from 12 to 15 miles beneath the surface, but new research suggests that they can come from more than 15 miles underground – into the Earth's mantle. From analysing data collected by state-of-the-art sensors over the last six months at California's Long Beach – where a 6.4 magnitude quake struck in 1933 – they found that the fault that it sits on top of, the Newport-Inglewood fault, extended into the mantle. The team believe that if a tremor occurs near to the surface, it could rattle down to the bottom of the fault and cause much more damage than previously thought. A California