This one is not as traumatic as some of the previous ones, but I can't think of any worse ones.  A few of you might remember that 5.8 earthquake Virginia had in 2011.  Well, as a person who has never experienced an earthquake, I thought (at first) that Washington D.C. was just bombed, but that thought was quickly let go.  After about 3 seconds in, I realized that "VIRGINIA is having a FUCKING EARTHQUAKE!" so I grabbed my sister who was watching TV on the couch, screaming, and I got her with me to crouch down to the floor.  If I hadn't done that, she would have been crushed in the head by a heavy speaker that fell where her head was.  But that was the most terrifying part in my life, because I truly thought (for a couple seconds) that a nuclear bomb went off 100 miles away in D.C.
Edit:
After the quake was over, I did what the entire east coast was doing:  I called my relative.  My mom was at a school that was made in the 50's, preparing the classroom for the year.  I was afraid that it may have collapsed, so I tried calling her.  However, because most people were doing what I was trying to do, the cell towers got congested and I couldn't make contact with her until about 15 minutes later.  That was pretty scary, too, not knowing if someone was alive and allright or not.  That made me start thinking:  What if my sister was injured?  I wouldn't have been able to call 911.  I don't know what I would have done then, except for stealing my mom's car and going to the hospital without a driver's license.  
This is also a problem that can occur in the future.  If a major terrorist attack happened, communications networks would be flooded, emergency services over-occupied, and stuff.  That is when a ham radio would be one of the most useful objects I own.