Level 3 Tsunami Modelling in Hawke's Bay Final Report

Abstract

In November 2021, Hawke's Bay Regional Council (HBRC) commissioned GNS Science (with funding supported by Toka Tū Ake EQC) to provide them with tsunami hazard maps for Napier and surrounding areas that are appropriate for them to use for land-use planning in the region. To create maps suitable for this purpose, HBRC has requested that GNS Science conduct a study to create probabilistic tsunami inundation hazard maps to a Level 3 standard for the Napier/Hastings Coastal Hazard Zone. This is Zone 73 in the National Tsunami Hazard Model (NTHM). HBRC also requested that the area to be mapped is extended beyond the zone out to neighbouring Cape Kidnappers Hazard Zone (Zone 74 in the NTHM) if that was appropriate. Maps were to cover four return periods: 100, 500, 1000 and 2500 years, and the latter return period needed to be consistent with the "Maximum Considered Tsunami" as defined in the MBIE guidelines. Hazard maps were also required for four different sea-level heights: the present day level at Mean High Water Springs (MHWS) and the MHWS level plus 0.65m, 1.0m and 1.99m of sea-level rise. In total, 16 different hazard maps were requested for the area of interest for each coastal zone.

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