Insights on Multistage Rock Avalanche Behavior From Runout Modeling Constrained by Seismic Inversions

Abstract

Inversion of low‐frequency regional seismic records to solve for a time series of bulk forces exerted on the earth by a landslide (a force‐time function) is increasingly being used to infer volumes and dynamics of large, highly energetic landslides, such as rock avalanches and flowslides, and to provide calibration information on event dynamics and volumes for numerical landslide runout models. Much of the work to date using landslide runout modeling constrained by seismic data has focused on using single‐phase models with frictional or velocity‐weakening rheologies. Awareness of multistage landslide initiations is increasing, with discrete failures separated in time contributing to the final impact of an event. Our work utilizes a method for incorporating seismic data as a calibration constraint for landslide runout models, considering variable rheologies and different initiation conditions. This study presents a systematic examination of multiple rheologies and initiation conditions, and shows how these factors affect the force‐time function derived from the landslide runout model. Our work confirms that, while rheology and fragmenting or initially coherent initiations affect the force‐time function, multiple collapses separated by tens of seconds have the greatest impact on the shape and amplitude. We apply this method to the analysis of three real rock avalanches to better constrain plausible initiation conditions and rheology parameters using both seismic and field data. This study provides insights on how assumptions about the initiation dynamics of the source zone and the runout model definition can aid in the interpretation of seismic inversions for multistage rock avalanches.

Insight into the critical morphological characteristics of earthquake-induced sequential rock avalanches in weathered-fractured rock cliffs

“…Most research interest in earthquake-induced rock avalanches has focused on the trigger mechanisms, the initiation failure characteristics, the movement dynamics, and the material properties of rock avalanches Guo et al, 2020a;Liu et al, 2020;. In particular, larger geological hazards derived from the process of rockfall occurrence or dynamic propagation, such as rock falls or debris flows, have attracted the attention of many researchers (Matasci et al, 2018;Zhang et al, 2018;Singeisen et al, 2020;Mitchell et al, 2022). However, both the analysis of dynamic propagation (Chen et al, 2006;Baggio et al, 2021; and the assessment of the rockfall movement distance (Chen et al, 2010;Zhu et al, 2020;Donati et al, 2021;Ma et al, 2021) were closely related to the influence of initiating damage factors on the triggering mechanism in rockfalls.…”