While neither caused any major damage, experts have warned that Monday's quake may have been associated with the Puente Hills thrust fault, which could one day cause a huge earthquake in Los Angeles.

Yesterday’s 4.1 earthquake, according to Fisher, hit close to the Wheeler Gorge fault, making it a thrust fault. A thrust fault is where one side of rocks is pushed up and over others ...

The researchers measured the orientations of smaller faults that formed in the vicinity of the Liachar Thrust — a major fault where a massive slab of rock is being shoved upon another.