Anthropogenic processes, natural hazards, and interactions in a multi-hazard framework

This paper presents a broad overview, characterisation and visualisation of the role of 18 anthropogenic process types in triggering and influencing 21 natural hazards, and natural hazard interactions. Anthropogenic process types are defined as being intentional, non-malicious human activities. Examples include groundwater abstraction, subsurface mining, vegetation removal, chemical explosions and infrastructure (loading). Here we present a systematic classification of anthropogenic process types, organising them into three groups according to whether they are subsurface processes, surface processes, or both. Within the three groups we identify eight sub-groups: subsurface material extraction, subsurface material addition, land use change, surface material extraction, surface material addition, hydrological change, explosion, and combustion (fire). We use an existing classification of 21 natural hazards, organised into six hazard groups (geophysical, hydrological, shallow Earth processes, atmospheric, biophysical and space hazards). Examples include earthquakes, landslides, floods, regional subsidence and wildfires. Using these anthropogenic process types and natural hazards we do the following: (i) Describe and characterise 18 anthropogenic process types. (ii) Identify 64 interactions that may occur between two different anthropogenic processes, which could result in the simultaneous or successive occurrence of an ensemble of different anthropogenic process types. (iii) Identify, through an assessment of > 120 references, from both grey- and peer-review literature, 57 examples of anthropogenic processes triggering natural hazards, citing location-specific case studies for 52 of the 57 identified interactions. (iv) Examine the role of anthropogenic process types (we use as an example vegetation removal) catalysing or inadvertently impeding a given natural hazard interaction, where the impedance of natural hazard interactions does not include deliberate hazard reduction activities (e.g., engineered defences). Through (i)–(iv) above, this study aims to enable the systematic integration of anthropogenic processes into existing and new multi-hazard and hazard interaction frameworks. As natural hazards occur within an environment shaped by anthropogenic activity, it is argued that the consideration of interactions involving anthropogenic processes is an important component of an applied multi-hazard assessment of hazard potential.