Analysis of Errors in Digitized Strong-Motion Accelerograms

To devise the optimum procedures for the processing of digitized strong-motion accelerograms, detailed error analysis is required. This paper summarizes some aspects of previous error analyses (Trifunac, 1970; Trifunac et al., 1971) and adds the results of several recent investigations. The error analysis described here is divided into two main parts. The first part deals with particular sources of errors. Each major source of error is analyzed individually with the aim of developing methods of error correction at the source wherever feasible. The second part deals with the overall effects of all errors at high and low frequencies. The objective of this part is to find the optimum frequency band in which the digitized accelerograms are least affected by the errors in the recordings and in the data processing steps, and which can be used to derive accurate velocity and displacement curves. The digitized accelerograms were found to represent accurately the absolute ground acceleration in the frequency band between 0.07 and 25 cps. This fre-quency band is significantly wider than anticipated and indicates a wide range of new research possibilities in strong-motion seismology and earthquake ngineering based on strong-motion accelerograms.