Earthquake‐Induced Chains of Geologic Hazards: Patterns, Mechanisms, and Impacts. (14th June 2019)

• Record Type: Journal Article
• Authors: Fan, Xuanmei; Scaringi, Gianvito; Korup, Oliver; West, A. Joshua; van Westen, Cees J.; Tanyas, Hakan; Hovius, Niels; Hales, Tristram C.; Jibson, Randall W.; Allstadt, Kate E.; Zhang, Limin; Evans, Stephen G.; Xu, Chong; Li, Gen; Pei, Xiangjun; Xu, Qiang; Huang, Runqiu
• Is Part Of: Reviews of geophysics. Volume 57:Number 2(2019)
• Page Start: 421
• Page End: 503
• Publication Date: 2019-06-14
• Subjects: earthquake‐induced landslides -- debris flows -- geohazards -- landscape evolution -- sediment cascade -- continental earthquakes; Geophysics -- Periodicals; 550.5
• DOI: 10.1029/2018RG000626
• Languages: English
• ISSNs: 8755-1209

Abstract

Abstract: Large earthquakes initiate chains of surface processes that last much longer than the brief moments of strong shaking. Most moderate‐ and large‐magnitude earthquakes trigger landslides, ranging from small failures in the soil cover to massive, devastating rock avalanches. Some landslides dam rivers and impound lakes, which can collapse days to centuries later, and flood mountain valleys for hundreds of kilometers downstream. Landslide deposits on slopes can remobilize during heavy rainfall and evolve into debris flows. Cracks and fractures can form and widen on mountain crests and flanks, promoting increased frequency of landslides that lasts for decades. More gradual impacts involve the flushing of excess debris downstream by rivers, which can generate bank erosion and floodplain accretion as well as channel avulsions that affect flooding frequency, settlements, ecosystems, and infrastructure. Ultimately, earthquake sequences and their geomorphic consequences alter mountain landscapes over both human and geologic time scales. Two recent events have attracted intense research into earthquake‐induced landslides and their consequences: the magnitude M 7.6 Chi‐Chi, Taiwan earthquake of 1999, and the M 7.9 Wenchuan, China earthquake of 2008. Using data and insights from these and several other earthquakes, we analyze how such events initiate processes that change mountain landscapes, highlight research gaps, and suggest pathways toward a more complete understanding of the seismic effects on the Earth's surface. Plain Language Summary: Strong earthquakes in mountainous regions trigger chains of events that modify mountain landscapes over days, years, and millennia. Earthquake shaking can cause many tens of thousands of landslides on steep mountain slopes. Some of these sudden slope failures can block rivers and form temporary lakes that can later collapse and cause huge floods. Other landslides move more slowly, in some cases in a stop‐start fashion during heavy rains or earthquake aftershocks. Debris from these landslides can clog channels, and during heavy rainfall, the debris can be transported downstream for many kilometers with catastrophic consequences. New landslides tend to happen more frequently than usual for months to years following an earthquake because the strong ground shaking has fractured and weakened the slopes. Other effects of large earthquakes can last, in various forms, over geologic time scales. Over the past two decades, our understanding of these issues has advanced because of the detailed study of the 1999 Chi‐Chi earthquake in Taiwan and the 2008 Wenchuan earthquake in China. We compile and discuss the results of research on these and other earthquakes and explain what we have learned, what we still need to know, and where we should direct future studies. Key Points: Coupled surface processes initiated by strong seismic shaking are important hazards in mountain landscapes Earthquake‐induced landslides pose challenges to hazard and risk assessment, management, and mitigation Multidisciplinary approaches further the understanding of the earthquake hazard cascade, yet challenges remain