A strong-motion accelerograph, an instrument used to measure the accelerations due to earthquake waves shaking the ground or structures. The accompanying record was of the Helena, Montana earthquake of October 31, 1935. In: Bulletin of the Geological Society of America, Vol. 49., No. 1, pp. 1-21.

Image ID: cgs02169, NOAA's Historic Coast & Geodetic Survey (C&GS) Collection
Photo Date: 1936 ca.
Credit: Collected Papers of Captain Nicholas Heck, NOAA Central Library

Category: Coast and Geodetic Survey/Geophysics Seismology/

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