What is a Geohazard?

‘Geohazard’ has become one of the classic terms of engineering geology, a contraction of the term geologic hazard. It seems that everyone knows what a geohazard is, but then seem to offer examples that betray significant differences of opinion. In this paper, we examine how the almost parallel emergence of the term through different disciplines, geography (disaster management), geology (environmental and urban geology) and geotechnical engineering, has led to a wide diversity of perspectives. We describe the diversity of geohazard classification and discuss how geohazards should be best viewed in the context of risk (the potential for undesirable consequences). Attention is drawn to the way in which geohazards are addressed in current guidance, notably IAEG C25 and Eurocode 7. In conclusion, we present the key points underpinning the concept of a geohazard.