It's dry as a bone in the LA Basin and all of that water is down there?.....
Why doesn't it reveal itself?
The faults of the LA Basin are different than the subductions zones. The subduction zone which one tectonic plate moves under another tectonic plate, sinking into the Earth’s mantle as the plates converge.The ones in the LA Basin is called a stike slip and thrust faults. A strike slip fault is a fracture formed where two parts of the earth’s crust (plates) slide past each other. The ones underneath Los Angeles is a blind thrust fault.If the fault plane terminates before it reaches the Earth’s surface, it is referred to as a blind thrust fault. Because of the lack of surface evidence, blind thrust faults are difficult to detect until they rupture.
Those two types faults are the most common in North America.
There is one thrust fault running from Dodger Stadium underneath Downtown Los Angeles straight down to Long Beach that is capable of producing a 7 plus earthquake. It called the Puente Hills Fault. It was discovered after the 1994 earthquake.
Drill, baby; DRILL! Drill there; drill now!