New Magnitude–Area Scaling Relations for the New Zealand National Seismic Hazard Model 2022

Abstract

We develop new magnitude–area scaling relations for application in the New Zealand National Seismic Hazard Model 2022 (NZ NSHM 2022) and future applications. A total of 18 published relations are selected, comprising the following tectonic and slip types: crustal strike-slip (seven relations), reverse (two relations), normal (two relations), subduction interface (five relations), and two dip-slip relations to augment the small number of available reverse and normal relations. The scaling relations are evaluated against an instrumental earthquake database flatfile, and scores are provided for each relation. Equations of the form Mw = log A + C are then used to develop mean and bounding relations for the suite of scaling relations. The final set of relations used in NZ NSHM 2022 is adjusted to be consistent with observations of major historical New Zealand earthquakes and U.S. Geological Survey practice. We also provide a second set of Mw = log A + C relations that are absent of these adjustments and so more directly reflect the results of our scoring of the published relations.