Seismotectonic model and probabilistic seismic hazard assessment for Papua New Guinea
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Seismotectonic model and probabilistic seismic hazard assessment for Papua New Guinea Hadi Ghasemi1 · Phil Cummins1,2 · Graeme Weatherill3 · Chris McKee4 · Martyn Hazelwood1 · Trevor Allen1 Received: 18 March 2020 / Accepted: 24 September 2020 © The Author(s) 2020
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. Keywords Seismic hazard · Fault sources · Papua New Guinea · Building code
* Hadi Ghasemi [email protected] 1
Geoscience Australia, Canberra, Australia
2
Australian National University, Canberra, Australia
3
German Research Centre for Geosciences GFZ, Potsdam, Germany
4
Port Moresby Geophysical Observatory, Port Moresby, Papua New Guinea
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Vol.:(0123456789)
Bulletin of Earthquake Engineering
1 Introduction 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). As a result, the region experiences significant seismic activity that includes large earthquakes, such as the 2018 Hela Province event (M7.5), which cause loss of life and widespread damage to buildings and infrastructure (McCue et al. 2018). In order to reduce societal and economic loss in future earthquakes, the likely ground motion from future seismic activity needs to be accommodated in PNG’s building code. The earthquake loading component of PNG’s current building regulations (Papu
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