A study on how to provide information on active faults with uncertainties

Abstract

There are many active faults in Japan. These active faults can cause earthquakes with very large damage, as exemplified by the Great Hanshin-Awaji Earthquake. On the other hand, earthquakes at active faults occur with long intervals between their activities. Therefore, the long-term evaluation of active faults involves a large uncertainty. To examine how information on active faults with uncertainty should be provided, we conducted a web-based questionnaire survey for residents in the areas where the Byobuyama, Enasan and Sanageyama-North fault zones are located and in municipalities in Gifu Prefecture and Aichi Prefecture where seismic intensity of 6- or higher is expected. The survey looked at the level of awareness of the faults, what information the residents pay attention to, and their reactions to earthquake risk information such as the 30-year probability. The results revealed the following. 1. the awareness of these fault zones is low. 2. the seismic intensity prediction map is useful to attract attention to educational flyers. 3. The percentage of people willing to access the QR code on the flyer decreases with age group. 4. If information on the 30-year probability of a specific active fault is presented to residents as a comparison to the 30- year probability of encountering other crisis events, there is a risk that the sense of urgency for the comparison may also be diminished. 5. showing the probability immediately before the occurrence of a past earthquake disaster increases the sense of crisis about future earthquakes.