Mass wasting

Japanese: mass wasting（英語表記）masswasting

...Geographical processes occurring in relatively cold climates, including snow erosion and frost erosion, are collectively known as periglacial processes.
[Other erosive actions]
Mass wasting is a type of erosion that is not caused by any specific external action, but is caused by the movement of unconsolidated material, such as weathered layers on a slope, due to gravity. It includes landslides, collapses, debris avalanches, creep (soil creep), and solifluction, and can also be called gravity erosion.

From [Terrain]

...This causes the destruction of existing land uses and structures, and causes serious problems in land conservation. Landslides and collapses are also geomorphological processes in valley areas, collectively known as mass wasting (gravity erosion), and result in distinctive topography. Landslides are particularly likely to occur in certain geologies.

From Mass Movement

...Therefore, mass movement removes slope material, erodes and lowers the ground surface, and plays an important role in the development of slope topography. Some say that the original meaning of the word is more appropriate to use the term "mass wasting." The term "mass movement" has been proposed as a translation, but this has not become widely used.

*Some of the terminology that refers to "mass wasting" is listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

Japanese:

…雪食や霜食などを含む比較的寒冷な気候下での地形営力は周氷河作用periglacial processと総称される。
［その他の浸食作用］
　特定の外作用によらないが，斜面上の風化層など未固結物質が重力によって移動されるタイプの浸食がマス･ウェースティングmass wasting(マス･ムーブメント)である。地すべり，崩壊，岩屑なだれ，クリープ(土壌匍行)，ソリフラクションを含み，重力浸食とも呼べる。…