2 important findings from LARSE
1)the alluvial basin beneath the san gabriel valley is 50% deeper than previously thought. Since thickness of alluvium affects the level of shaking, the quake hazard here is larger than thought.
2) the San Madre and Whittier faults merge, at depth, into what the seismologists have called the "master blind thrust fault". This fault extends to the East towards San Andreas fault. Stress can be transferred along the connected fault system into the LA basin, increasing the quake hazard for LA