P waves travel about 8 km/s in the upper mantle...but a lot of the time delay if the rupture propagation along the fault....I won't bother to get a map out, but let's say 300 km rupture and 3 km/s rupture speed (I'm not sure of that, but I think it can be 3 to 5 km/s?? So, up to 100 s of rupture. So, the rupture that is closest to LA occurs maybe 60 to 100 s after it started....then...it takes some time for the S waves (meaning, shear, not surface) to arrive in the deepest part of LA Basin...where they slow down and amplify. It's been almost 20 years since I had an earthquake seismology and seismotectonics classes so I don't remember speeds of surface waves.....
Chris