As a result of the widespread use of the landslide classifications of Varnes (1978), and Hutchinson (1988), certain terms describing common types of flow-like mass movements have become entrenched in the language of engineering geology. Example terms include debris flow, debris avalanche and mudslide. Here, more precise definitions of the terms are proposed, which would allow the terms to be retained with their original meanings while making their application less ambiguous. A new division of landslide materials is proposed, based on genetic and morphological aspects rather than arbitrary grain-size limits. The basic material groups include sorted materials: gravel, sand, silt, and clay, unsorted materials: debris, earth and mud, peat and rock. Definitions are proposed for relatively slow non-liquefied sand or gravel flows, extremely rapid sand, silt or debris flow slides accompanied by liquefaction, clay flow slides involving extra-sensitive clays, peat flows, slow to rapid earth flows in nonsensitive plastic clays, debris flows which occur in steep established channels or gullies, mud flows considered as cohesive debris flows, debris floods involving massive sediment transport at limited discharges, debris avalanches which occur on open hill slopes and rock avalanches formed by large scale failures of bedrock.

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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.

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