Multi-hazard risk pathway scenarios associated with unconventional gas development: Identification and challenges for their assessment

In this paper we summarize a number of risk pathway scenarios that are often claimed in literature as of priority for risk analyses in unconventional gas development. The resulting scenarios are structured in diagrams representing causal relationships between events. We argue that science is called to fill gaps regarding the main processes characterizing the involved events and defining the conditions under which their occurrence may be enhanced or inhibited. In this way, these scenarios can be more objectively parameterized, making their quantitative assessment a more feasible task and opening the way for the formulation of appropriate risk mitigation strategies.