The relationship between bulk-mass momentum and short-period seismic radiation in catastrophic landslides

The relationship between bulk-mass dynamic properties of catastrophic landslides and the generation of short-period seismic waves is investigated, with a particular focus on the momentum of the landslide mass and the envelope of high-frequency seismograms. Twelve very large landslides that occurred in different geological settings worldwide between 1999 and 2014 are selected for study, based on the existence of detailed descriptions of their force histories, determined from long-period seismic waves (frequency lower than 0.1Hz), as well as the availability of nearby high-quality short-period seismic recordings. A high average correlation (0.94) is found between the modulus of the landslide momentum and the envelope of the high-frequency seismograms, band-passed filtered between 3 and 10Hz, recorded on nearby stations. The best correlation is seen during the acceleration phase of each landslide. Comparatively poor average correlation (0.57) is found between the modulus of the landslide force and the seismogram envelopes. A possible scaling between the momentum and the amplitude of short-period radiation is investigated. The maximum amplitudes of short-period seismograms for the nine best recorded landslides are corrected for local attenuation and correlated with the maximum momentum of the landslides. The nine data points scatter around a best fitting line that defines a nearly linear relationship between momentum and peak short-period radiation. It is hypothesized that bulk-mass momentum linearly modulates landslide processes that generate short-period seismic waves but that the efficiency of short-period radiation is highly variable between landslides.