I really believe that some of our dreams are subconscious manifestations of issues or problems in our daily lives, and I dream about water a LOT.
Water, in dreams, represents emotion. My water dreams (ooh, that sounds much racier than it really is) are usually about fish tanks (repressed or contained emotion), or a car I'm in accidentally driving off a bridge (too complicated and requiring much explanation).
The tsunami dream apparently means that 'you are being overwhelmed by some repressed feeling or unconscious material that is rising up to the surface. You are experiencing some unhappiness and emotional instability in a waking situation.'
I also often dream of houses. Houses represent your own soul or self, and the different rooms are metaphors for aspects of your psyche. I dream of houses with lots of kitchens (the nurturing part of me) and bedrooms. Hmm. I'll just say that maybe I need more... sleep.
So -- dreaming of a tsunami threatening my home... you don't have to be Freud to put that one together, right?