Why was my dream soundless?

Well, you might know about the earthquake that happened in Japan. My cl had a unit in language about natural disasters and we talked a lot about. I might've been thinking a lot about it cause I had a dream. In it, I was at some museum(which I've never been at before but somehow knew it was a museum) and an earthquake occurred. I wasn't experiencing this, just helplessly watching it happen. Also, it was soundless. I was expecting to hear screams and people panicking but I didn't. I just saw the ground shaking and everyone with a scared expression. Why did this happen? Also, I've had what you could call a psychic dream before in which I saw the face of my cousin-in-law though I'd never seen her before. Me and my older sister had this same dream on the same night. Why am I having such dreams?