I definitely stopped & dropped during the recent 7.1 Earthquake in Southern California, only it was my character taking cover while I figure out if I should be concerned that the world around me was shaking!
But at the same, it is hard to resist the opportunity to shoot at your opponent while the earth is rumbling around you. The earthquake added a sense of immersion considering the grenades were exploding in the game. Being a native southern Californian we are used to the ground rumbling from time to time. Which helped me to consider what an amazing occurrence the timing of it all in that synchronistic type fashion.