Subsidence “Subsidence” is a geologic condition, in which a localized mass movement occurs, resulting in the downward settlement of the earth over time. When subsidence occurs, the actual ground surface elevation is lower. This occurrence of the ground surface sinking is typically caused by groundwater table and aquifer reductions, by which the soils become more…

Soil Creep Definition Soil Creep is a type of landslide that entails the slow and gradual movement of a soil mass (or even some loose rock) materials.

Water Table Water Table: In the hydrogeology branch of geology, the water table represents the surface of an unconfined groundwater aquifer, where the hydraulic pressure is equal to atmospheric pressure. Additionally, a water table is present in a perched groundwater zone. Although, there is no water table in a confined aquifer.

Trench Dam Trench Dam: Per the Los Angeles Department of Building and Safety (LADBS) Methane Code, Ordinance Number 175790, a trench dam is part of a methane mitigation system. A trench dam is essentially a subsurface barrier that exists within a furrow or ditch, that is adjacent to the foundation of a building in a…

Mafic Definition In geology, “mafic” is a term that describes an igneous rock that has an abundance of darker color minerals.

Runoff (R) The term “Runoff” (R) in hydrogeology and geology refers to the part of rainfall which accumulates on the ground surface and naturally forms into flowing streams.