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![A strong-motion accelerograph, an instrument used to measure the accelerationsdue to earthquake waves shaking the ground or structures cgs02169.jpg A strong-motion accelerograph, an instrument used to measure the accelerationsdue to earthquake waves shaking the ground or structures](/sites/default/files/styles/max_1300x1300/https/s3.amazonaws.com/s3-east-testmedia-noaa.woc.noaa.gov/dam/Photos/legacy/pl23_cgs02169.jpg?itok=2zrAcauS)
Description
A strong-motion accelerograph, an instrument used to measure the accelerationsdue to earthquake waves shaking the ground or structures. The accompanyingrecord 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 credit: Collected Papers of Captain Nicholas Heck, NOAA Central Library)