Device for detecting seismic motion

摘要

A device detects seismic motion by linear motion of a seismic detection ball within an inner casing. Radial protrusions on the inside surface of a bottom wall of the inner casing maintain linear back-and-forth motion of the seismic detection ball while in contact with the casing bottom wall. On the inside surface of the perimeter wall of the inner casing, radially inward protrusions are formed parallel to one another to prevent rotation of the seismic detection ball in a circular path along the casing perimeter when it is lifted up from the casing bottom wall. The seismic detection ball is formed from a material unaffected by magnetic fields. The inner casing is suspended within an outer casing, in a condition of damped swaying. The inner casing is composed at least partially of a metallic material to provide sufficient weight to insure reliable automatic centering.