The integration of acceleration records as performed by the U. S. Coast and Geodetic Survey to produce velocity and displacement curves has nearly always required the use of arbitrary “adjustments,” in addition to the three legitimate adjustments involved in fixing the two constants of integration and the acceleration axis. These additional adjustments were justified on the assumption of accelerometer zero shifts. An improved accelerometer eliminated the possibility of zero shifts, thereby preventing the continued use of the former adjustments. Since then acceptable integration results have not been obtainable, except only for short periods of ground motion.
The Carder displacement meter has thoroughly proved its superiority over integration as a means for obtaining displacement information of general engineering significance, and is being increasingly used for this purpose.