Earthquake‐Induced Chains of Geologic Hazards: Patterns, Mechanisms, and Impacts

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.

Initiation and Runout of Post‐Seismic Debris Flows: Insights From the 2015 Gorkha Earthquake

“…Mobilization of saturated sediments as debris flows is a critical link in the chain of "cascading hazards" that follows in the wake of large earthquakes, fires, and floods (Cannon et al, 2001;Costa, 1984;Fan et al, 2019;Huang & Li, 2014;Jakob & Hungr, 2005). Consequences include economic and infrastructure damage and loss of life.…”

Investigation of Landslides that Occurred in August on the Chengdu–Kunming Railway, Sichuan, China

“…These earthquakes may reduce the strength of the soil-rocks at the site [27] so that even the latest earthquake (on 29 July 2019) recorded near the site was only 3.3 magnitude in July to August in 2019 and which was 200 km away from the site. The earthquake was also a significant cause of the slide [29][30][31][32].…”

Socio-environmental extremes: rethinking extraordinary events as outcomes of interacting biophysical and social systems

“…Recent assessments also explicitly try to account for different types of interactions among hazards (Gill & Malamud, 2014;Kappes et al, 2012) . Specific case studies that focus on the interactions among biophysical hazards include: secondary hazards induced by volcanic eruptions (Neri et al, 2008) , earthquakes (Fan et al, 2019) , and concurrent extreme weather events (Forzieri et al, 2016;Vogel et al, n.d.) , sequences of droughts, floods and landslides (Nones & Pescaroli, 2016) , and wildfires triggering floods, landslides, and debris flows (Bendix and Cowell, 2010;Cannon et al, 2008;Moody et al, 2013 ;Staley et al, 2005) . Gill & Malamud (2017) provide a framework for natural hazard interactions, some of which yield extreme outcomes, and a review of documented cases, moving beyond the accounting for 'all-hazards-at-a-place' (Hewitt et al, 1971) .…”