| definition |
- A general term covering a wide variety of mass-movement landforms and processes involving the downslope transport, under gravitational influence, of soil and rock material en masse. Usually the displaced material move over a relatively confined zone or surface of shear. The wide range of sites and structures, and of material properties affecting resistance to shear, result in a great range of landslide morephology, rates, patterns of movement, and scale. Landsliding is usually preceded, accompanied, and followed by imperceptible creep along the surface of sliding and/or within the slide mass. Terminology designating landslide types generally refers to the landform as well as the process responsible for it, e.g. rockfall, translational slide, block glide, avalanche,
mudflow, liquefaction slide and slump.
A Landslide Advisory may be included in other types of advisories such as ones for earthquakes, volcanic activity, and floods. Landslide advisories may also take the form of landslide susceptibility and probability maps.
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| Abstract from DBPedia | Landslides, also known as landslips, are several forms of mass wasting that may include a wide range of ground movements, such as rockfalls, deep-seated slope failures, mudflows, and debris flows. Landslides occur in a variety of environments, characterized by either steep or gentle slope gradients, from mountain ranges to coastal cliffs or even underwater, in which case they are called submarine landslides. Gravity is the primary driving force for a landslide to occur, but there are other factors affecting slope stability that produce specific conditions that make a slope prone to failure. In many cases, the landslide is triggered by a specific event (such as a heavy rainfall, an earthquake, a slope cut to build a road, and many others), although this is not always identifiable.地すべり（じすべり、英語：landslide）とは、土砂の移動形態の一つで斜面上で発生する代表的な土砂災害の一つである。後述のように地すべりの定義は人や地域によって若干異なるが、比較的傾斜の緩い斜面において地下水の作用により、地中に形成されるすべり面を境に上部の土塊（移動体、移動ブロックなどとも呼ばれる）が比較的ゆっくりとずり落ちるように原形を保ったまま斜面下方に向けて移動する（浮力によって上部の塊と下部の塊が分離し地下水に浮いていると表現されることもある）現象を指すことが多い。 地すべりの別名を「山津波」ということもあるが、人によっては土石流のことを山津波と言うこともあり混同されやすい。地すべりと土石流はどちらも水の作用で大量の土砂が動く現象という点では同じだが、地すべりが地下水で動くのに対し、土石流は渓流の水で土砂が動く点で現象としては明確に異なるものである。ある程度の勾配を持つ傾斜地における地すべりは移動速度が速く、狭義の土砂崩れ（山崩れ、斜面崩壊とも）との区別は曖昧である。これを崩壊性の地すべりもしくは地すべり性の土砂崩壊などと呼んで狭義の土砂崩れと区別する研究者もおり、従来土砂崩れとされてきた現場でも急傾斜地の地すべり性のものがあると考えられている。 (Source: http://dbpedia.org/resource/Landslide) |
