Why do I dream of a tidal wave?

I dream I am walking on a deserted beach, as I am walking I am conscious of

the noise of gulls, and of a sudden deafening roaring sound.

I look up and there is a devastating tidal wave racing towards the beach.

There is a massive wind caused by this wave and my nostrils are burning with

sea ozone..there is nothing I can do. This is so vivid, and fairly regular

to the point that I am finding all I can out about sunami's....WHY?