Gerstenberger, M.C.; Kaneko, Y.; Fry, B.; Wallace, L.M.; Rhoades, D.A.; Christophersen, A.; Williams, C.A. 2017 Probabilities of large earthquakes in central New Zealand. Lower Hutt, N.Z.: GNS Science. GNS Science miscellaneous series 114. 21 p.; doi: 10.21420/BCD8-8G90
Abstract
In this project, we have estimated the 1-year and 10-year probabilities for the occurrence of large earthquakes in central New Zealand. Following the November 14th, 2016 Kaikōura MW 7.8 earthquake, there was widespread triggering of slow slip earthquakes (SSE) on the Hikurangi subduction zone. At that time, little research had been done to understand the implications of SSE for the occurrence of future larger earthquakes. In December, 2016 initial modelling was done to estimate the probabilities of larger earthquakes within the next year in central New Zealand; this was the first time such work had been done anywhere. In this project, we have improved upon the initial models and have constructed new physical and statistical forecast models that account for the interaction of SSE and crustal earthquakes. Part of this process included two international workshops. In the first workshop, preliminary models were reviewed by the international panel and revisions and recommendations for new models were discussed. In the second workshop, a non-consensus structured expert elicitation procedure was used to evaluate the models and observations and to estimate the revised probabilities as shown in the table below. The best estimates for the next year for M7.0+ and M7.8+ represent increases of 20% and 100% respectively over the long-term estimates from the National Seismic Hazard Model. The upper bounds for both of these magnitude range estimates area significantly greater increase. Similarly, the upper bounds on the decade estimates are a significant increase over the long-term estimates. (auths)
