The Northridge earthquake occurred at 4:30 a.m. local time on January 17, 1994. Northridge is located about 30 km northwest of Los Angeles. This earthquake had a 6.9 moment magnitude. The hypocentral depth was 19 km. The duration was about 10 seconds to 20 seconds. The earthquake occurred along a "blind" thrust fault, close to the San Andreas fault. Note that a blind fault is a fault which does not extend to the surface. In other words, it is buried.