yes very true ! there are certain decibel of vibration which we can't hear but animal and birds can.... I remember an incident in 2002 or 3 (not sure about year) in south India...........seeing my cat behaving stupidly i told people around that something is going to happen and same evening earthquake came............so we have to observe our pets and other animals to find out any calamity cause they are so precise in detecting all this.
