Interesting...and surprising. But, probably flawed...I read what they are doing...but they don't seem to take into account the deep basins like L.A., and probably parts of the Bay area, where somewhat distant large quakes can make strong ground motions...like happened in Oakland from the 70 km distant Loma Prieta quake....

Or, at least I don't see any change in colors that correspond to basins....Ventura basin should have far higher probablity than the Santa Monica Mts, for example.
Chris