accelerograms

An accelerogram is a time history of ground acceleration produced by an earthquake at a specific site. Recorded with seismographs or accelerometers, it plots acceleration versus time for each horizontal and vertical component of ground motion, typically expressed in metres per second squared (m/s²) or in g units. Real accelerograms capture the violent onset, peak values, and frequency content of ground shaking, and they may require baseline corrections and instrument response removal before use.

In engineering practice, accelerograms serve as input for dynamic structural analysis and ground-motion characterization. Two common quantities derived from accelerograms are the peak ground acceleration (PGA) and the peak ground velocity (PGV). Analysts also compute spectral accelerations at different periods to build response spectra, which are used to assess a structure’s response to earthquake shaking. Accelerograms can be used directly in nonlinear time-history analyses or transformed into scaled or synthetic records that meet specified design requirements.

There are real accelerograms, recorded from past earthquakes, and synthetic accelerograms generated by stochastic or physics-based models to supplement available data or to explore hypothetical scenarios. Processing steps include filtering, removing tilt and baseline drift, and correcting for instrument response. Accelerograms are archived in seismological databases and are central to seismic design codes, where they inform probabilistic and deterministic ground-motion models, seismogram libraries, and performance-based engineering.