Many geologic processes affect the state, including coastal and fluvial flooding and erosion, earthquakes and the liquefaction and shaking they produce, land movement such as subsidence and landslides, and radon emission from rock and soil. These processes are natural and they have been active throughout Indiana's geologic history. When these processes affect the human population they are commonly called "geologic hazards." Other geologic hazards have been created by human activities. Three in particular are: subsidence associated with subsurface mining, coastal erosion of man-made structures because of longshore drift, and the potential of accidents related to open mining pits and quarries.