Do landslides follow landslides? Insights in path dependency from a multi-temporal landslide inventory

Jalal Samia,Fausto Guzzetti,Arnold Bregt,Jakob Wallinga,Arnaud Temme,Francesca Ardizzone,Mauro Rossi

doi:10.1007/s10346-016-0739-x

Abstract

Landslides are a major category of natural disasters, causing loss of lives, livelihoods and property. The critical roles played by triggering (such as extreme rainfall and earthquakes), and intrinsic factors (such as slope steepness, soil properties and lithology) have previously successfully been recognized and quantified using a variety of qualitative, quantitative and hybrid methods in a wide range of study sites. However, available data typically do not allow to investigate the effect that earlier landslides have on intrinsic factors and hence on follow-up landslides. Therefore, existing methods cannot account for the potentially complex susceptibility changes caused by landslide events. In this study, we used a substantially different alternative approach to shed light on the potential effect of earlier landslides using a multi-temporal dataset of landslide occurrence containing 17 time slices. Spatial overlap and the time interval between landslides play key roles in our work. We quantified the degree to which landslides preferentially occur in locations where landslides occurred previously, how long such an effect is noticeable, and how landslides are spatially associated over time. We also investigated whether overlap with previous landslides causes differences in landslide geometric properties. We found that overlap among landslides demonstrates a clear legacy effect (path dependency) that has influence on the landslide affected area. Landslides appear to cause greater susceptibility for follow-up landslides over a period of about 10 years. Follow-up landslides are on average larger and rounder than landslides that do not follow earlier slides. The effect of earlier landslides on follow-up landslides has implications for understanding of the landslides evolution and the assessment of landslide susceptibility.

Highlights

Existing landslide research recognizes the critical role that is played by external triggers along with intrinsic attributes of site that contribute to landslide occurrence (Carrara et al 1999; Crozier 1986; Guzzetti et al 2008)
Do landslides follow landslides? We found that the multi-temporal landslide inventory of our study site recorded substantial overlap between landslides and an associated reduction in the fraction of the study area affected by landslides (Fig. 5)
Regardless of the mechanism, our findings suggest that there is path dependency among landslides: older landslides act in some way or other as initiators for follow-up landslides for a certain period

Summary

Introduction

Existing landslide research recognizes the critical role that is played by external triggers (e.g. extreme rainfall events, earthquakes and human interferences) along with intrinsic attributes of site (e.g. slope and lithology) that contribute to landslide occurrence (Carrara et al 1999; Crozier 1986; Guzzetti et al 2008). Qualitative approaches emphasize the role of experience and expert knowledge in determining landslide susceptibility (Van Westen et al 2003). Quantitative approaches assume that conditions that lead to landslide occurrence in the past and present are likely to cause landslides in the future, the probability of occurrence of future landslides is determined using correlations among various conditioning factors and landslide inventories by statistical methods (Tien Bui et al 2016; Van Westen and Terlien 1996). Deterministic quantitative approaches use detailed geotechnical and hydrological data in combination with statistical models to estimate the probability of slope failure (Aleotti and Chowdhury 1999; Van Westen and Terlien 1996)

Methods

Results

Discussion

Conclusion