Abstract
The coupled effect of earthquakes and rainfall is rarely investigated in landslide susceptibility assessments although it could be crucial to predict landslide occurrences. This is even more critical in the context of early warning systems and especially in cases of extreme precipitation regimes in post-seismic conditions, where the rock masses are already damaged due to the ground shaking. Here, we investigate this concept by accounting for the legacy of seismic ground shaking in rainfall-induced landslide (RFIL) scenarios. We do this to identify whether ground shaking plays a role in the susceptibility to post-seismic rainfall-induced landslides and to identify whether this legacy effect persists through time. With this motivation, we use binary logistic regression and examine time series of landslides associated with four earthquakes occurred in Indonesia: 2012 Sulawesi (Mw = 6.3), 2016 Reuleut (Mw = 6.5), 2017 Kasiguncu (Mw = 6.6) and 2018 Palu (Mw = 7.5) earthquakes. The dataset includes one co-seismic and three post-seismic landslide inventories for each earthquake. We use the peak ground acceleration map of the last strongest earthquake in each case as a predisposing factor of landslides representing the effect of ground shaking. We observe that, at least for the study areas under consideration and in a probabilistic context, the earthquake legacy contributes to increase the post-seismic RFIL susceptibility. This positive contribution decays through time. Specifically, we observe that ground motion is a significant predisposing factor controlling the spatial distribution of RFIL in the post-seismic period 110 days after an earthquake. We also show that this effect dissipates within 3 years at most.
Highlights
The conditions promoting the occurrence of a landslide are governed by various climatic, morphologic, geomorphologic, geotechnical, seismic and anthropic factors and their complex interactions (Budimir et al 2015; Reichenbach et al 2018)
We use the first post-seismic inventory associated with the Reuleut earthquake (Mw = 6.5) because it appears as a rare event where many rainfall-induced landslides (RFIL) occur on a site only a few landslides are triggered by the earthquake
We resample the IMERG product to the same resolution of the peak ground acceleration (PGA) grid via an inverse distance weighted interpolator (Watson and Philip 1985); this being done for spatial consistency between rainfall and ground shaking proxies. 2. —we introduce the rainfall events extracted in the previous step as independent variables in a post-seismic RFIL susceptibility model
Summary
The conditions promoting the occurrence of a landslide are governed by various climatic, morphologic, geomorphologic, geotechnical, seismic and anthropic factors and their complex interactions (Budimir et al 2015; Reichenbach et al 2018). These causative factors are categorized as predisposing conditions and triggering factors (e.g. IAEG 2001; Tanyaş et al 2019a; Fan et al 2019). Landslide triggering factors (i.e. rainfall, earthquake, human activity, snowmelt, volcanic processes), on the other hand, generally refer to external stresses that cause an immediate response in terms of slope stability (Crosta et al 2012). The coupled effects of earthquakes and rainfall are rarely examined (e.g. Bontemps et al 2020; Chen et al 2020a; Sæmundsson et al 2018; Sassa et al 2007)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
