How long was the shaking?
The actual time it takes for a fault to slip depends on the size of the earthquake. A magnitude 5 earthquake slips for about a second; a M6 for a few seconds; a M7 for several seconds. The duration of shaking you actually feel from an earthquake depends in part on the distance you are from the epicenter of the earthquake. If you are close, the shaking will be more violent, “faster”, and may not last as long. If you are further away, the high-frequency “fast” shaking will have been “absorbed” into the earth’s crust, you will feel are the longer-period, more rolling motions, and they may be of longer duration. In short, the duration is different in different places, even for the same earthquake. In addition, observers in the nearby locations may describe different directions depending on the type of building they are in, and how each perceives the shaking.
