When I was a Santa Fe Los Angeles Division Engineer, I was on a couple of trains that were moving when earthquakes hit. I really did not know that there was an earthquake either time, until contacted by radio and told to stop the train. They inspect every bridge and all track before they allow any movement of trains.
However, I did have an interesting experience while stopped. On a trip in freight service from San Bernardino to Los Angeles, we headed in (entered the siding) and stopped at the west end of the siding at Corona. This was in the early 1970's, and the Dispatchers did not communicate directly to trains by radio then. At that time the Third District was single track from Riverside Jct. to Atwood, and the area west of the city of Corona was pasture land. The Head Brakeman went to the phone booth to find out how many trains we could expect to meet there, and returned with the information that we would be in the hole for three. I rested my feet on the heater in front of the Engineer's seat and was daydreaming, when I felt the engine begin gently rocking. Instantly I checked the brake valves and gauges, to be sure the air brakes were still applied, as it felt like we were starting to roll. Then I could see out the side window that we were indeed still stopped. It was an earthquake. The grass in the pasture was rolling in waves like a lake's surface on a breezy day. We were there for 3 hours while they inspected bridges and track, and then we got a signal to leave the siding and finish our trip. And those three eastbounds we were supposed to meet at Corona? Well, the Dispatcher changed his mind while everything was stopped. One of them was in the siding at Prado Dam, the second one at Esperanza, and the third at the end of two tracks at Atwood. So, do earthquakes make for better dispatching? Obviously! 
