Fling Effects from Near‐Source Strong‐Motion Records: Insights from the 2016 Mw 6.5 Norcia, Central Italy, Earthquake

Abstract

We propose a semiautomatic processing scheme (extended BASeline Correction [eBASCO]) for recovering the tectonic fling from near-source records. The method, based on a piecewise linear detrend of the strong-motion (SM) recordings, is applied to reconstruct the ground displacement field of the 30 October 2016 M w 6.5 earthquake in central Italy. The robustness of the results is checked against geodetic measurements, remote sensing data, ground-motion simulations, and existing empirical models for fling amplitude. The outcomes of eBASCO are analyzed with the goal of testing its capability to preserve long-period content in near-source SM recordings affected by tectonic fling, different from standard processing schemes based on bandpass filtering. Comparison of peak ground displacements, peak ground velocities, and spectral displacements shows that long-period ground motion recorded over and in proximity of the fault can be underestimated by standard processing. Spectral displacement ordinates can diverge up to the 25% for periods longer than 5 s when an appropriate baseline correction is made.