Probabilistic seismic hazard assessment of PNG
Channel: GeoscienceAustralia
Date: 2021-03-04

Date: 30 September 2020

Speakers: Hadi Ghasemi, Phil Cummins and Mark Edwards

Summary:
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. 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 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 southern part of the New Guinea Highlands Block. In comparison with the seismic zonation map in the current design standard, it can be noted that the spatial distribution 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.

We also discuss how the seismic hazard map of PNG is being used to underpin its building code, including what steps have been taken by GA together with the Government of PNG to promote uptake of the new hazard map by PNG’s earthquake engineering community.

About the Speakers:

Hadi Ghasemi is a senior seismologist in the Regional Development Section at GA. He received his PhD from the International Institute of Earthquake Engineering, Iran in 2009 and prior to joining GA, he was a postdoctoral fellow at the Earthquake Research Institute at University of Tokyo. Since joining GA, he has been involved in DFAT-funded regional programs covering a wide range of activities such as establishment of near real-time earthquake impact alerting in Indonesia, and development of a community-based earthquake monitoring network in Papua New Guinea.

Phil Cummins is engaged as both a senior research scientist at GA , where he applies earthquake and tsunami science in GA’s Regional Development Section, and a Professor of Natural Hazards at ANU, where he combines research with teaching in natural hazards. He received his PhD in Geophysics from U. California Berkeley in 1988 and worked as a postdoctoral and research fellow at the Australian National University (ANU) until 1996, when he moved to the Japan Center for Marine-Earth Science and Technology (JAMSTEC). After leading a geodynamics research unit at JAMSTEC, in 2001 he took up a position leading earthquake and tsunami hazard research at Geoscience Australia (GA).

Mark Edwards is the Director of the Vulnerability, Resilience and Mitigation Section at Geoscience Australia. He leads a multi-disciplinary team developing engineering, economic and social vulnerability models in the Community Safety Branch. He is an engineer with 14 years of industry experience as a professional engineer followed by 23 years of research with a scope that has widened from earthquake vulnerability to multi-hazard risk. He participates in the development of Australian building design standards for a range of natural hazards. He has led the collaborative development of a guidance document to enable the use of the recently completed earthquake hazard assessment for Papua New Guinea for building design.