Relationship between earthquake-induced excess pore water pressure and strong ground motion observed in a monitored fill slope

Abstract

The generation of excess pore water pressures during ground shaking can be an important earthquake-induced landslide trigger. We measured pore water pressures and seismic ground motion in filled slopes and examined their relationships obtained from 29 observed earthquakes. We characterized pore water pressure and seismic waveforms by calculating several parameters that described their magnitudes and durations. We demonstrate that whilst the instantaneous magnitude of strong ground motion is responsible for the generation of excess pore water pressure, the magnitude of excess pore water pressure generated is related to the peak ground acceleration (PGA) and Arias Intensity (AI) in the observed PGA range of 0.12–1.9 m/s2. The magnitude of peak ground velocity (PGV) also produced a strong correlation although a few exceptional events where long period component (>1 s) of seismic waves is dominant were observed. Lastly, the time-span over which excess pore water pressure continues to rise is affected by the duration of seismic ground motion. Our study shows how excess pore water pressures can be generated in fill-slopes during seismic events. This new knowledge could be used to improve future earthquake-induced landslide hazard assessment.