Abstract
Papua New Guinea (PNG) lies in a belt of intense tectonic activity that experiences high levels of seismicity. Although this seismicity poses significant risks to society, the Building Code of PNG and its underpinning seismic loading requirements have not been revised since 1982. This study aims to partially address this gap by updating the seismic zoning map on which the earthquake loading component of the building code is based. We performed a new probabilistic seismic hazard assessment for PNG using the OpenQuake software developed by the Global Earthquake Model Foundation (Pagani et al. in Seism Res Lett 85(3):692–702, 2014). Among other enhancements, for the first time together with background sources, individual fault sources are implemented to represent active major and microplate boundaries in the region to better constrain the earthquake-rate and seismic-source models. The seismic-source model also models intraslab, Wadati–Benioff zone seismicity in a more realistic way using a continuous slab volume to constrain the finite ruptures of such events. The results suggest a high level of hazard in the coastal areas of the Huon Peninsula and the New Britain–Bougainville region, and a relatively low level of hazard in the southwestern part of mainland PNG. In comparison with the seismic zonation map in the current design standard, it can be noted that the spatial distribution of seismic hazard used for building design does not match the bedrock hazard distribution of this study. In particular, the high seismic hazard of the Huon Peninsula in the revised assessment is not captured in the current building code of PNG.
Highlights
The territory of Papua New Guinea (PNG) is riven by the seismically active boundaries between three major tectonic plates and at least eight microplates (Baldwin et al 2012; Koulali et al 2015; Wallace et al 2014)
To build the hazard model we used two key global datasets that have become available recently: the latest versions of the International Seismological Centre (ISC)–GEM earthquake catalogue and a new subduction zone geometry model (Slab 2.0, see Hayes et al 2018). This manuscript describes the development of the 2019 PNG seismic hazard assessment (PSHA19) through: the development of a homogenous earthquake catalogue for the region; the development of seismic-source models for active faults and intraslab seismicity; and the selection and weighting of the ground-motion models (GMMs) used in the assessment
None of the GMMs selected in the subsequent section explicitly consider style-of-faulting as a parameter for intraslab earthquakes, so this latter choice will not impact on the hazard and is assigned purely for consistency with the regional tectonics
Summary
The territory of Papua New Guinea (PNG) is riven by the seismically active boundaries between three major tectonic plates and at least eight microplates (Baldwin et al 2012; Koulali et al 2015; Wallace et al 2014). In the present study we revise the PSHA16 model by implementing two key recommendations by Ghasemi et al (2016): i.e., developing a more comprehensive earthquake catalogue for the region and including a fault–source model that makes use of recent Global Navigation Satellite System (GNSS). This manuscript describes the development of the 2019 PNG seismic hazard assessment (PSHA19) through: the development of a homogenous earthquake catalogue for the region; the development of seismic-source models for active faults and intraslab seismicity; and the selection and weighting of the ground-motion models (GMMs) used in the assessment. The updated hazard model is discussed in the context of the seismotectonic setting of PNG, and in comparison with the seismic zonation map in the current design standards
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