Tehnuka invited as ECR plenary speaker at IAVCEI 2023 volcanology conference in Rotorua

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.”

Liquefaction structures in Lake Rotoroa (Hamilton Lake)

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).

Vertical flame-like dike penetrating through organic lake sediment (removed during the CT data processing). The dike’s source bed is located within the ~20,000-years-old Hinuera Formation, which underlies the present-day lake sediments.
Five dikes penetrating downwards from a volcanic ash (tephra) layer, having been deposited ~15,600 years ago. The occurrence of these dikes suggest earthquake activity must have happened after the deposition of this tephra layer.
Richard before handing in his dissertation.

Participation at QuakeCoRE Annual meeting

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

PhD student Jordanka (left) and Prof. Rolando Orense at the annual QuakeCoRE meeting in Napier.

CT scanning reveals downward tephra injectites

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.

Sediment cores were scanned using a new medical CT scanner at Hamilton Radiology. From left to right: Dr Vicki Moon, Dr Max Kluger, Jordanka Chaneva, and Nic Ross
X-ray image of a sediment core, which shows downward injection structures from (tentatively) Rotorua tephra layer into underlying organic-rich host sediments
CT image of sediment core. Upper left: Downward injection structures from (tentatively) Tuhua and Mamaku tephras

UoW team presents research at Waikato Regional Hazards Forum

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.

Jordanka Chaneva, PhD student with the Tephra Seismites group, gives an overview of plans to analyse tephra (ash) layers in lake sediments using geotechnical methods, to understand how they deform during earthquakes
Some of the University of Waikato attendees (From top left: George McQuillan, Dr Vicki Moon, Dr Max Kluger, Dr Adrian Pittari, Dr Willem de Lange, Prof David Lowe, Tori Gibbons, Dr Tehnuka Ilanko, and Jordanka Chaneva)