The papers in this special issue of the SAJG were produced from a DST funded project undertaken by the South African Council for Geoscience (CGS) from the years 2010-2014. The aim of the project was to develop a South African Geological Hazards Observation System (SAGHOS). Geological hazards are naturally occurring or human-induced phenomena that present a risk life and infrastructure. The geohazards investigated include landslides, coastal geohazards, terrestrial erosion, earthquakes, mining related deformation, sinkholes and subsidence, geochemical hazards, sinkholes and subsidence, problem soils, tsunami and groundwater vulnerability. The study of geohazards involves the assessments of their mechanisms of formation, impact areas and long-term monitoring. Remote sensing and spatial analysis techniques are instrumental in the assessment and monitoring of geohazards.