footwall
Geological term for the block of rock below a fault plane. Contrasts with 上盤 (hanging wall).
See also: 上盤
The footwall of a fault refers to the rock mass that lies below relative to the hanging wall.
Compound of 下 (した, 'below') and 盤 (ばん, 'board, plate, rock mass'), referring to the lower rock block in a fault.