Characteristics of effective California earthquake scenarios

Practitioners in California have long considered scenarios of plausible, hypothetical earthquakes to be an effective part of their toolkit for mitigation progress, as evidenced by continued widespread use. Through 66 interviews of 77 scenario users and developers, we provide insights into how scenarios are used in mitigation work and characteristics that make them effective. Both users and developers viewed scenarios very positively, as measured by a high Net Promoter Score. Interview participants named the following characteristics as making scenarios effective for motivating mitigation: (1) a robust, collaborative co‐production process including multiple disciplines and end users/stakeholders from the beginning, with involvement throughout; (2) scientific and technical credibility, both through the reputation and standards of the organization that prepared the scenario and the quality of the particular work; (3) plausibility and realism of the event; (4) practical applicability, with results clearly describing impacts of importance to end users; (5) recommendations developed that specifically identify potential actions, policies and mitigation measures, and plans to implement them; with clear mechanisms for follow‐on work with stakeholders that supports implementation of mitigation measures; and (6) communication in clear language and graphics, using appropriate channels for each audience and with graphics such that people who are not earthquake professionals can understand the findings and act on them.