A Comparison of Records from the Linear Strain and Pendulum Seismographs

Citation

Pye, Willard Dickison (1937) A Comparison of Records from the Linear Strain and Pendulum Seismographs. Master's thesis, California Institute of Technology. doi:10.7907/2Y9E-AP60. https://resolver.caltech.edu/CaltechTHESIS:03282010-114406134

Abstract

The linear strain seismograph and its action has been described by Benioff (1). Essentially the instrument consists of two piers 20 meters apart in a north-south direction. A rod is connected rigidly to the southern pier and extends to within a short distance of the northern one. At equal intervals along the rod are supports which permit only longitudinal movement of the rod. Attached to the northern pier is an electromechanical transducer (2). The rod is insulated with asbestos, and the whole instrument is placed in a long insulated tube to reduce temperature effects on the rod.

An incoming wave from an earthquake produces a variation in the separation of the piers, which causes a change in the separation of the free end of the rod and the northern pier. This sets up an induced e.m.f. in the transducer proportional to the velocity with which the displacement takes place. The induced e.m.f. activates a galvanometer, the deflection of which is recorded photographically.

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