THE DISTRIBUTION CHARACTERS AND ORIGIN MECHANICS OF GROUND FISSURES HAZARD IN HEBEI PLAIN

Earth fissures are a serious geological hazard in Hebei Plain.This paper presents their temporal and spatial variations.The majority of earth fissures occur in alluvial-proluvial apron zone.Earth fissures express themselves at land surface as straight line,crenata,polygonal line and forniciform.The spatial distribution of ground fissures can be characterized as directional,cluster and systematic.Length and intensity of earth fissures also vary with time.The primary causes for earth fissuring includes earthquake activities,groundwater overdraft and ground collapse.