Abstract

We investigate a large rockfall that occurred along the cliffs of the Hudson River Palisades, United States, on 12 May 2012, using seismic signals recorded at a distance of about 2 km. A rockfall involves a combination of rock detachment, acceleration, impact, and settling motion, each of which involves forces that load and unload the Earth and generate seismic waves. We characterize different phases in the seismograms and associate them with specific stages of the rockfall. Using the analytical solution to Lamb’s problem, we simulate the seismic‐wave propagation between the event and seismic station taking into account the elastic properties of the crust in the Palisades region. The dynamics and the source history of the Palisades rockfall are reconstructed by analyzing the characteristics of the seismic signal. From the modeled force history, we infer that the bulk of the mass detached from about 30 m above the highest part of the riverbank and that lower bounds of the mobilized mass and volume are 3.1×104  metric  tons and 1.1×104  m3, respectively.

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