A ∼200-year relative sea-level reconstruction from the Wellington region (New Zealand) reveals insights into vertical land movement trends

Abstract

The sea-level rise threat to New Zealand's coastal cities is regionally exacerbated due to spatially varying vertical land movement (VLM). At Wellington, the capital city, situated adjacent to a major active plate boundary, strong regional spatial and temporal variability of VLM is indicated by the relatively short (∼25 year-long) continuous Global Navigation Satellite Systems (GNSS) network, but until now longer records of VLM have been lacking. Here, a ∼ 200-year-long relative sea-level reconstruction is presented from Pāuatahanui salt marsh in the northern Wellington region. The foraminifera-based relative sea-level reconstruction indicates that ∼1 ± 0.45 m of sudden uplift occurred during the 1855CE Mw 8.2 Wairarapa earthquake. Following this, Pāuatahanui has experienced a mean rate of relative sea-level rise (1855CE to present) of 1.5 ± 0.6 mm/yr, or 2.4 ± 0.8 mm/yr since the start of the twentieth century, consistent with ongoing subsidence in concert with climate-driven sea-level rise. Further acceleration to >3 mm/yr since the 1990s (with 4 mm/yr also possible if the full 95% confidence range is taken into consideration) is consistent with the globally documented acceleration in sea-level rise, although low model precision hampers confidence in this interpretation. This record is the first of its kind from a tectonically complex setting in New Zealand, shedding light on the effects of the historically significant 1855 earthquake, and fills a gap between millennial-scale and contemporary records of VLM with important implications for future sea-level projections in the region.

Metadata

Item Type:	Article
Authors/Creators:	King, Daniel J. (vbm508@york.ac.uk) Newnham, Rewi M. Rees, Andrew B.H. Clark, Kate J. Garrett, Ed (ed.garrett@york.ac.uk) Gehrels, W. Roland (roland.gehrels@york.ac.uk) Naish, Timothy R. Levy, Richard H.
Copyright, Publisher and Additional Information:	© 2023 The Authors Funding Information: Katharina Hecht (Utrecht University/Victoria University of Wellington), Jiten Patel (Victoria University of Wellington), Charlotte Pizer (Victoria University of Wellington) and Garth Archibald (GNS Science) are thanked for their invaluable assistance in fieldwork and surveying. Dr. Michael Lechermann (ESR Christchurch) and Dr. Levi Bourke (ESR Christchurch) are thanked for the generation of 210Pb data, and Dr. Maarten Blaauw (Queen's University, Belfast) and Adelaine Moody (Victoria University of Wellington) are thanked for their assistance in the generation of 210Pb age models. Dr. Valerie van den Bos (Victoria University of Wellington) is thanked for her work preparing our pollen samples for analysis, and her help with coding issues. Dr. Sophie Williams is also thanked for her useful discussions and further help with coding issues. Dez Tessler is also thanked for help with issues affecting the RTK GPS device during fieldwork. We also thank Marianna Terezow (GNS Science), Dr. Martin Crundwell (GNS Science), and Dr. Richard Pearce (National Oceanography Centre, Southampton) for their help with scanning electron microscopy, used to generate the micrographs presented in Fig. 2. Rohini Biradavolu (Victoria University of Wellington) and the staff of Arapaki Manners Library are thanked for their assistance in finding difficult-to-access literature. Furthermore, Dr. Bruce Hayward is thanked for his invaluable discussions and opinions over the course of this project. This project was funded by and is a contribution to the NZ SeaRise Project, an MBIE (Ministry of Business, Innovation and Employment)-funded program. Data are available at: http https://doi.org/10.6084/m9.figshare.23618931 Funding Information: This project was funded by and is a contribution to the NZ SeaRise Project, an MBIE (Ministry of Business, Innovation and Employment)-funded program. Data are available at: http https://doi.org/10.6084/m9.figshare.23618931
Keywords:	Co-seismic uplift,Foraminifera,Inter-seismic subsidence,Saltmarsh,Sea-level projections
Dates:	Published: 1 January 2024 Published (online): 7 December 2023 Accepted: 4 December 2023
Institution:	The University of York
Academic Units:	The University of York > Faculty of Sciences (York) > Environment and Geography (York)
Depositing User:	Pure (York)
Date Deposited:	26 Feb 2024 16:00
Last Modified:	16 Oct 2024 19:48
Published Version:	https://doi.org/10.1016/j.margeo.2023.107199
Status:	Published
Refereed:	Yes
Identification Number:	10.1016/j.margeo.2023.107199
Related URLs:	http://www.scopus.com/inward/record.url?...
Open Archives Initiative ID (OAI ID):	oai:eprints.whiterose.ac.uk:209647

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A ∼200-year relative sea-level reconstruction from the Wellington region (New Zealand) reveals insights into vertical land movement trends

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