There was an earthquake in the Seattle area around 20 years ago. I was in a Verizon cell site radio shack installing equipment when I heard banging of some of cable supports outside. I saw the motion of the equipment around me so I ran outside. At that point I got to see two very strange phenomenon. The first was the land, on the horizon, wave like an ocean swell from right to left for quite some distance. The other was watching the top of a 150ft cell site monopole tower whip back and forth 10ft for about 20 seconds. I knew the tower wasn't going over because I know how massive the concrete base in the ground. But it was an experience I'll never forget. Later on I talked to some coworkers who were actually driving across the Tacoma Narrows bridge when it happened. They said many people started pulling over to see if they had a flat tire. (This was the bridge that was built AFTER the other one fell down due to an engineering flaw)