During an emergency sometimes there can be a crowd surge. People trying to get out of a building through the most redly available exit. While this can be a bit exaggerated by Hollywood, it is not unheard of. Most crowd surges happen when people are trying to get INTO an event such as a concert but during an emergency such as an earthquake when there is a sudden panic to get out of a structure anything can happen.
There are a couple of things to remember when ever you are in crowds. Try to always know where there are exits, conventional fire exits and unconventional. By unconventional I mean windows or any feature of a structure which may allow for your escape. Knowing your athletic ability avenues of escape could open up for you and not many other people. You have to judge your own capabilities and take a leap of faith. But you need to be evaluating these features of a structure in advance. You should be scanning and accessing when ever you go into any building. Where are the conventional fire exits? What unconventional avenues of escape are there? Who is with me and what will I have to do to accommodate their needs? Which characters in the crowd are suspect?
If there is a crowd surge there are a couple things you can do. The first is increase your personal space. Put you hand on your hips with your elbows pointing out, try to give yourself a larger footprint to avoid being crushed. In some cases the crowd will become so dense that you won’t even have the space to expand your ribs to breathe, suffocation is common from crowd surge crush. Another thing you should do is get to a column and put your back to it on the down flow side of the surge. Think of water running past a bridge pylon.
In addition look for natural breaks in the continuity of buildings. Sometimes there are displays or closets with inset walls which will provide cover as the crowd surges past. If you get caught in the middle of a surge there is little you can do. The force is too great to fight your way out. The best thing you can do is think ahead and visualize clear avenues of escape, try to remain calm and think like you are swimming in a raging rapids. You aren’t going to be able to swim straight towards an object on shore. Try to estimate the rate of travel of the surge and calmly work your way to safety.