Baseline Correction of Ground Motions for Linearly Detrended Accelerograms

ABSTRACT

By revisiting the accelerograms from 42 strong-motion stations in Hualien County that recorded the 2018 Mw 6.4 Hualien earthquake, we identified that the released “raw accelerograms” were linearly detrended to remove baselines. Baseline correction for these linearly detrended accelerograms is challenging, because the baseline drift patterns are more complex than typically recognized ones. To deal with this problem, here we propose a jerk correction pattern in addition to our previously proposed tilt correction pattern and cumulative correction pattern. The modified baseline correction procedure corrects all 126 accelerograms for three directions of the 42 strong-motion stations. The recovered ground displacements are consistent with geodetic measurements, demonstrating complex surface deformations in the close vicinity of the Milun fault.