Author: Max

Hard on the heels of the paper published in January 2024 in the New Zealand Journal of Geology and Geophysics, members of the tephra seismites team joined GNS Science colleagues to renew their research on the Te Puninga Fault at two newly dug trenches across the fault (which is near Morrinsville) in late February 2024.

The excavations and field analyses of the deposits in the freshly exposed trench walls (see photos) were supervised by Dr Genevieve Coffey of GNS Science with support from GNS colleagues and also some geoscience staff from University of Auckland and University of Canterbury as well as University of Waikato.

The research on the fault is part of a joint project involving funding from the Marsden Fund provided to the University of Waikato (supporting the tephra seismites project) and from Toka Tū Ake EQC to GNS Science.

The Te Puninga Fault is important for the tephra seismites project because it is the closest fault to the north-eastern part of the Hamilton Basin, the focus of the project centred on liquefied tephra layers preserved in numerous lakes in the basin.

The trenching-based research on Te Puninga Fault represents the last phase of field work to be undertaken under the banner of the Marsden-funded tephra seismites project, which finished at the end of February 2024.

Various analyses and interpretations of arising from detailed examination and sampling of deposits exposed in the trench walls (at both sites) will continue through the year.

We are pleased to advise that we have in the past few weeks (January 2024) published an open access paper in the New Zealand Journal of Geology and Geophysics on our findings from research undertaken on the recently discovered Te Puninga Fault near Morrinsville. The paper is available here:

https://www.tandfonline.com/doi/full/10.1080/00288306.2023.2296875

The article is based on analyses of two trenches excavated across the fault in February 2022 (see photos). The purpose of the work was to examine the possible size and frequency of earthquakes on the fault, which would potentially have had an impact on the lakes and associated liquefied lacustrine tephras we are investigating in the adjacent Hamilton lowlands.

The work forms part of our Marsden-funded ‘tephra seismites’ project and was co-funded by a grant by Toka Tū Ake EQC led by Dr Pilar Villamor of GNS Science.

For more information about the findings just published, please see the media release here:

https://www.scimex.org/newsfeed/te-puninga-fault-can-cause-infrequent-but-large-earthquakes-in-hauraki-plains

We are happy to announce that a paper was recently published at Sedimentary Geology that provides an overview about our first research outcomes of the Tephra-Seismites project. The paper can be downloaded for free for a limited time period.

You can access our paper here: Kluger et al. (2023)

We are glad to announce that Tehnuka, who is a postdoc in our Tephra-Seismites group, will give an Early-Career Researcher Plenary talk at the volcanology conference of the International Association of Volcanology and Chemistry of the Earth’s Interior (IAVCEI) 30 Jan-3 Feb 2023.

Although she is currently working with tephras, Tehnuka’s main research area until now has been in volcanic degassing. She is particularly interested in how we can understand volcanic processes and plumbing through gas geochemistry, and in developing methods to collect, analyse, and interpret gas data from active volcanoes. Much of her work to date has used ground-based remote sensing to investigate open-vent volcanism.

The topic of her ECR plenary talk will be “Un-mixing messages: finding meaning in volcanic gases“. Further details and an abstract can be found at https://confer.eventsair.com/iavcei2023/plenary-speakers.”

M.Sc. student Richard Melchert has worked for the Tephra-Seismites group since mid 2021 and assisted with lake coring, sediment description, and other laboratory work. In his recently submitted dissertation entitled “Sedimentology and characterisation of soft-sediment deformation structures within lacustrine successions in 20,400-year-old Lake Rotoroa, Hamilton, New Zealand”, he studied liquefaction structures in Lake Rotoroa, which provide evidence for earthquake activity since the formation of the lake around 20,000 years ago.

Richard used a range of techniques, including X-ray computed tomography (CT), ground penetrating radar (GPR), and grain size analyses. The CT scans enabled him to visualise the liquefaction structures in three dimensions (see figures below).

Tephra Seismites PhD student Jordanka Chaneva attended the QuakeCoRE Annual meeting in Napier between 29th August to 1st September 2022. She presented part of the on-going triaxial testing research through a poster entitled “Cyclic undrained behaviour and liquefaction resistance of pumiceous, non-plastic sandy silt”. The poster-abstract is now available to read at: http://www.quakecore.nz/wp-content/uploads/2022/08/2022-Abstract-Book-FINAL.pdf

Join the upcoming NZGS Webinar presented by Max Kluger, who will provide an overview about newest findings from the Tephra-Seismites project.

The webinar will take place on 28th March 12:30PM to 1:30PM. Registration is free an can be made at https://www.engineeringnz.org/courses-events/event/hamiltons-seismic-hazard/

This week we analysed the internal structure of the sediment cores we collected at Rotoroa, Rotokaeo, and Waiwhakareke using a medical CT scanner at Hamilton Radiology. This method provides a first estimation about whether or not seismites (tephras deformed by earthquake activity) are present in the sedimentary record. Next week we plan to cut the cores lengthwise for detailed sediment description and sampling.

Members of the Tephra Seismites group and colleagues from UoW Earth Sciences attended the annual Waikato Regional Natural Hazards Forum at Hauraki District Council, Paeroa, on Friday 20 November. They joined colleagues from district and regional councils, Civil Defence and Emergency Management, and other research institutes to hear about and discuss aspects of natural hazard management and mitigation, with a focus on community engagement.

The Waikato team, including four (post)graduate students, gave a series of short ‘lightning talks’ on current research about newly-discovered faults in Hamilton and the liquefaction potential of lacustrine ash layers.

On Friday, 13th November 2020, paleoseismologists Dr Pilar Villamor and Dr Kate Clark of GNS Science visited the Tephra Seismites team at University of Waikato, to discuss their future collaboration. They will work together to map faults within the Hamilton lowlands, and eventually link the occurrence of fault ruptures to liquefaction observed in lacustrine tephra layers.