Patent ID: 6356204
Filing Date: 2002-03-12
Classification: G01V

Abstract:
A method for detecting vibration signals from a stationary object or objects, said signals being indicative of an impending earthquake, characterized by the steps of:providing first and second sensors for detecting vibration within a structure responsive to vibration of a fixed substrate upon which the sensor is mounted, said sensors each featuring an electronic detection circuit to convert said vibration to electronic signals, and a transmitter to transmit said electronic signals via transmission means; providing a processing unit having receiving means for receiving electronic signals transmitted by said sensors, a timer circuit for measuring the duration of the signals received from said sensors, and a logic circuit including a potentiometer circuit; mounting said first and second sensors to said fixed structure; determining the natural vibration frequencies of said structure; presetting said potentiometer circuit to said vibration frequencies of said structure; comparing electronically with said logic circuit any extraneous vibration signal different from said preset vibration frequencies of said structure and allowing passage of electronic signals indicative of P-waves acting on said structure; measuring with said timer circuit the duration and temporal overlap of said signals indicative of P-waves from each of said sensors; determining whether said duration and temporal overlap of said extraneous signals exceed predetermined levels indicative of an impending earthquake; and activating alarm means when said duration and temporal overlap indicate an impending earthquake.