Dating coseismic marine terrace formation during the Kaikoura 2016 earthquake

Lead Research Organisation: University of Glasgow
Department Name: School of Geographical & Earth Sciences

Abstract

The recent earthquake in Kaikoura, New Zealand on 14th November 2016 resulted in the uplift of large stretches of coast. Previously intertidal rocky shore platforms cut into bedrock are now stranded high and dry above the tides. The opportunity to observe the marooning of raised marine terraces is rare, yet these are ubiquitous landforms flanking the coasts in tectonically active settings around the globe, from the edges of the Mediterranean Sea to the Pacific margin of the Andes and Rocky mountains. These marine terraces previously formed at sea level are important spatial and chronologic markers of the interactions between tectonic uplift and eustatic sea level change that allow reconstruction of a history of tectonic uplift rates. Terraces can be dated using cosmogenic isotopes (CIs), but the accuracy of ages is tied to inherent (and untested) assumptions about the nuclide inventory at the time of terrace abandonment. Moreover, their formation and abandonment are poorly understood because the processes involved are not typically observed in real time.

The goal of this project is to address both of these existing knowledge gaps and use a shore platform instantaneously uplifted and abandoned during the 14th November 2016 Kaikoura, New Zealand earthquake to directly observe the processes of formation and abandonment of marine platforms. The Kaikoura earthquake demonstrated that the formation of stranded marine terraces can be due to instantaneous, coseismic uplift of previously active rocky shore platforms. We will measure 10Be concentrations from the surface of a newly stranded shore platform in a transect of in-situ bedrock samples so as to determine the apparent platform age at the time of terrace formation. We will also use measured 10Be concentrations in concert with existing data on shore platform and coastal erosion to understand the prior history of shore-platform development leading up to the earthquake in order to understand the inheritance of 10Be accumulated during active coastal development. The proposed work is vital for the provision of a baseline for future studies both locally and globally. Sampling must take place as soon as possible, prior to any significant breakdown of the surface due to subaerial weathering, deposition or human modification. This rare event provides a unique opportunity to calibrate and validate existing models for platform abandonment and evolution, and in turn improve our assessment of vertical tectonic rates and associated hazards in tectonically active coastal regions around the globe.

Planned Impact

Tectonic uplift and the interactions with relative sea level change and coastal erosion is of concern to a wide variety of organisations. Knowledge about earthquakes and uplift of coasts is required to quantify future earthquake and coastal erosion hazards and risks. This project will provide a stepping stone towards achieving these impact goals by pump-priming future research efforts with high quality baseline data, but will also deliver some shorter term impact goals to maximise the value of this short project whilst providing a springboard to achieve impact with future research.

Potential Beneficiaries

Primary beneficiaries of this work will be government organisations with responsibility to quantify the likelihood of earthquake hazards and associated risk, and those with responsibility for managing coastal erosion and storm surge risks in the face of rising sea levels and projections of heightened storm severity and frequency. Secondary beneficiaries of this project will be secondary school students and the general public.

Impact will maximised through three engagement activities:

1) Compile a report on the "State of science" of rock coast processes targeted at coastal practitioners and non-specialists, focused on the relationship between coastal erosion and geological processes. The document will be written with the support from PPs at Scottish Natural Heritage, Environment Canterbury and GNS Science and will be circulated widely to government agencies, local authorities, non-government organisations and consultants both in the UK and New Zealand.

2) Deliver new educational resources on rocky coast geomorphology to geography teachers, presented to the Scottish Geography Teachers Association. This will provide high school students with a better understanding of how rocky coasts are formed and develop through time, and how our coasts are likely to change in the future.

3) Engage the public with our research through face-to-face and online promotion. Members of the public will benefit through delivery of a public lecture and group workshop towards the end of the project. A web page will be established where regular project updates will be posted and promoted through social media.

We will establish and maintain close relationships with our project partners to embed them in these activities and our future research design. We will assess the extent to which these activities have improved our beneficiaries' knowledge and understanding using targeted surveys. Finally, we will promote activities widely using a strategic approach to social media that will maximise the exposure of our research to key organisations, the public and academic communities.

Publications

10 25 50
 
Description The north-east coast of North Island New Zealand was suddenly uplifted by as much as 6.5 m during the Kaikoura earthquake in November 2016. Using geological dating techniques that us the time rocks have been exposed near the Earth surface, we have identified that the section of coast that has experienced the most uplift (~ 6.5 m) is geologically young. Taken together and when combined with a physics-based model for rock coast erosion, our results suggest that these coastal rocks have been exposed in the last couple of thousand years, and therefore that tectonic activity on this fault block has also occurred in the recent past, prior to the 2016 earthquake.
Exploitation Route Our results have important implications for earthquake hazard assessment and coastal erosion/protection. Firstly, the young age ofthe studied shore platform suggests that the Hope Fault that ruptured during the 2016 earthquake (but had not previously in historical times) has been recently active during the Holocene, and we hope to provide constraints on how active once we have competed our modelling study. Secondly, we will be able to constrain the timing and rates of shore platform and coastal erosion over centennial to millennial timescales, and suggest the time-frame over which this earthquake event might afford some coastal protection. Thirdly, the careful, bespoke approach to 10Be target preparation in young samples with fine grain size pushes the boundary of what is possible in cosmogenic nuclide science, and we are working closely with NERC facilities to ensure the benefits can be realised by other practitioners. Finally, this study is (to our knowledge) only the fourth world wide that quantifies shore platform and rock coast erosion over these longer timescales using cosmogenic geochronology, further highlighting the potential of these techniques to improve our understanding of rock coast geomorphology.
Sectors Education,Environment,Government, Democracy and Justice,Culture, Heritage, Museums and Collections,Transport

 
Description Our findings have been used as a case study in new Higher Geography teaching resources developed as part of the pathways to impact for this project. These materials have been discussed with Geography teachers in a local school for uptake in the next academic session.
First Year Of Impact 2018
Sector Education
 
Description ANSTO Facilities Grant
Amount $16,840 (AUD)
Organisation Australian Nuclear Science and Technology Organisation 
Sector Public
Country Australia
Start 01/2018 
End 12/2018
 
Description ANSTO Facilities Grant
Amount $50,412 (AUD)
Funding ID 10955 
Organisation Australian Nuclear Science and Technology Organisation 
Sector Public
Country Australia
Start 04/2018 
End 04/2018
 
Description Will It Stay or Will It Go? Determining the relationship between marine terraces formed by earthquakes and coastal erosion
Amount $958,000 (NZD)
Funding ID 18-UOO-139 
Organisation Royal Society of New Zealand 
Sector Learned Society
Country New Zealand
Start 04/2019 
End 03/2022
 
Title RPM-Cosmo 
Description Coupled numerical model to predict cosmogenic isotope concentrations in tandem with shore platform morphodynamics 
Type Of Material Improvements to research infrastructure 
Year Produced 2018 
Provided To Others? No  
Impact None as yet 
 
Title RPM-Cosmo 
Description Coupled numerical model for the prediction of cosmogenic nuclide concentrations on shore platforms developed using an exploratory morphodynamic model. 
Type Of Material Computer model/algorithm 
Year Produced 2018 
Provided To Others? No  
Impact None as yet 
 
Description Timing and rates of shore platform formation in Australia constrained by cosmogenic isotopes 
Organisation University of Melbourne
Country Australia 
Sector Academic/University 
PI Contribution Measurement and modelling of cosmogenic isotopes on the coast of Australia to determine shore platform origin and development.
Collaborator Contribution Field work conducted and contribution of process-based understanding in addition to site specific knowledge of coastal geomorphology.
Impact Successful ANSTO proposal: Timing and rates of shore platform formation in Australia constrained by cosmogenic isotopes
Start Year 2017
 
Description Using cosmogenic radionuclides to improve quantification and prediction of coastal erosion in a warming world 
Organisation Australian Nuclear Science and Technology Organisation
Country Australia 
Sector Public 
PI Contribution Measurement and modelling of cosmogenic isotopes on the UK coast to determine shore platform origin and development. Field work conducted and contribution of process-based understanding in addition to site specific knowledge of coastal geomorphology.
Collaborator Contribution High precision measurement of low concentration 10Be in rock samples by accelerator mass spectrometry.
Impact None as yet
Start Year 2017
 
Description Will It Stay or Will It Go? Determining the relationship between marine terraces formed by earthquakes and coastal erosion 
Organisation University of Otago
Country New Zealand 
Sector Academic/University 
PI Contribution We will contribute expertise in modelling cosmogenic radionuclide concentrations with rock coast morphodynamics to understand long term erosional history of rocky coasts.
Collaborator Contribution Uplifted marine terraces are coastal landforms widespread globally and used to infer past earthquakes, sea-levels and rates of landscape change. However, interpretations of past earthquakes are controversial because we do not understand the conditions under which uplifted terraces are removed from the landscape. This understanding is vital because the removal (through erosion) of one or more terrace leads to erroneous estimates of past earthquake activity. Our recent fieldwork shows new marine terraces along the Kaikoura-Marlborough coast and on the Kaikoura Peninsula following the November 2016 earthquake. Our extensive data from Kaikoura covers 43 years, providing a baseline from which we can determine the longevity of these new terraces. Currently, understanding of longevity is limited by the lack of a model that includes erosion processes and terrace preservation. Using new advances in dating methods we can identify if terraces have been removed from the landscape. We will develop a multi-factorial framework to establish 'preservation thresholds' for marine terraces. Our framework will enable informed predictions of past earthquakes and coastal change and contribute to the global response to sea level rise and climate change impacts on coasts since we will assess how long newly uplifted terraces will last in the landscape.
Impact None as yet
Start Year 2019
 
Description Will It Stay or Will It Go? Determining the relationship between marine terraces formed by earthquakes and coastal erosion. 
Organisation University of Otago
Country New Zealand 
Sector Academic/University 
PI Contribution Development of a proposal for the Marsden Fund in New Zealand to the Royal Society of New Zealand.
Collaborator Contribution How quickly are marine terraces preserved or removed from the landscape and do marine terraces record all earthquakes? We will answer this question using the uplifted Kaikoura coast following the November 2016 earthquake. We can do this because we have 43 years of monitoring prior the earthquake and 12 months of new data against which we can make further measurements. We will develop models to predict coastal change and test these at other sites in New Zealand. Our results will also aid coastal management responding to sea level rise and climate change impacts on coasts because uplift alters coastal vulnerability.
Impact Submission to the Marsden Fund, Royal Society of New Zealand. Funding Successful.
Start Year 2017
 
Description  
IP Reference  
Protection Protection not required
Year Protection Granted
Licensed No
Impact Models developed during this grant available via GNU General Public Licence
 
Title Coupled Morphodynamic-Cosmogenic Isotope Model for Rocky Coasts 
Description Coupling of cosmogenic isotope production model developed by Hurst et al. (2017) with new morphodynamic model for rock coast evolution developed by Matsumoto et al. (2016). 
Type Of Technology Software 
Year Produced 2018 
Open Source License? Yes  
Impact Model to be used on a variety of projects related to cosmogenic dating of rocky coasts 
URL https://mdhurst1.github.io/RoBoCoP_CRN_Documentation/
 
Description Consultation with Higher Geography Teachers on resources needed for teaching about coastal erosion. 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Schools
Results and Impact Discussion with Higher Geography teachers on the nature of teaching coastal geomorphology for SQA Higher Geography qualifications. Shared existing resources to help steer the development of new teaching resources with a focus on active learning. The new resources were subsequently developed and form a core component of the pathways to impact.
Year(s) Of Engagement Activity 2018