Well, the 6.4 is considered a foreshock to the 7.1, being a smaller event which proceeds a larger one in the same area in a small time frame.

And when it comes to damage, location is everything. The Sylmar And Northridge quakes occurred in densely populated areas, and some areas were built on rather soft ground which makes the shaking worse.

The 6.4 and 7.1 quakes weren’t quite as devastating since Ridgecrest isn’t heavily populated.

Add in the fact that during the last 40+ years we as a people have made decent strides in designs that while not earthquake-proof, certainly tend to stand up to the damage much better than they used to...