Nankai-Tokai subduction hazard for catastrophe risk modelling

Speaker: David Spurr
“The Headquarters for Earthquake Research Promotion (HERP) released a new probabilistic national seismic hazard map for Japan in March 2005. The technical documentation included extensive details of the hazard modelling and made available for the first time a comprehensi ve national fault model in a form easily implemented in earthquake risk modelling. The hazard models were primarily developed for longer-term public good applications. However, they have by almost default been adopted by several large modelling companies for use in earthquake insurance and other situations where a shorter term view of risk often applies.

This seminar explores issues around the adaption of the HERP fault model for use in a catastrophe risk modelling system that is used in support of annual reinsurance renewals for large Japanese co-operative insurers. The discussion specifically focuses on the Nankai subduction interface rupture recurrence, where problems were encountered that heavily impacted reinsurance risk estimates. An extensive investigation of the subduction behaviour has been undertaken and an alternative model developed and implemented. The main issues addressed are interactions between segment ruptures, the recurrence behaviour and modelling of the Tokai segment.”