Tephra Seismites at IAVCEI Scientific Assembly, Rotorua

Two weeks ago, some of the Tephra Seismites group attended the IAVCEI (International Association of Volcanology and Chemistry of the Earth’s Interior) 2023 Scientific Assembly in Rotorua. The conference, with the University of Waikato a major sponsor, was originally scheduled for February 2021. Twice postponed due to COVID, it was a relief that the meeting could proceed (with 860 in-person and 203 virtual participants) despite the wet weather and temporary closure of Auckland Airport.

Photo showing the Events Centre carpark with the old Bath House building in the background. There are IAVCEI conference banners attached to the light poles in the carpark. — IAVCEI 2023 conference banners above the Events Centre carpark

We presented two talks on behalf of the group, in the session ‘Tephrochronology: new methods and applications for chronostratigraphy and beyond’.

The first was a broad overview of the project, covering some of our recently published work, and our work with X-ray CT to identify and characterise tephras and seismites: ‘Tephra seismites preserved in unconsolidated organic lake sediments in the Hamilton lowlands, New Zealand, indicate paleoearthquake activity since 17.6 ka’ (presented by Tehnuka).

The next talk focused on our work at Rotoroa/Hamilton Lake, and findings from Richard Melchert’s thesis: ‘Using ground-penetrating radar and X-ray computer tomography to survey and characterise distal tephras in lake sediments, Hamilton lowlands, New Zealand’ (presented by David).

Photograph taken from the audience of a conference talk. It shows a large screen displaying maps (on the right), two convenors (seated, centre), and Tehnuka (left, wearing a mask). — Left: Tehnuka presenting in the IAVCEI tephrochronology session. Right: View over Rotoroa (Hamilton Lake), looking roughly south to southeast (Photo courtesy of O.E. McLeod)

Photograph of Rotoroa (Hamilton Lake), surrounding parklands, houses, the taller hospital buildings on the opposite shore, and a hilly skyline in the far distance. — Left: Tehnuka presenting in the IAVCEI tephrochronology session. Right: View over Rotoroa (Hamilton Lake), looking roughly south to southeast (Photo courtesy of O.E. McLeod)

Tehnuka also gave an ECR (Early Career Researcher) Plenary, showing how we can unravel volcanic gas data to understand both magmatic and non-magmatic processes.

Photograph from the audience of an auditorium with two large screens above the stage. Tehnuka is presenting at the lectern. The screens show a photo of the summit of an ice-covered volcano emitting a blue-white plume against a blue sky, with the title 'Un-mixing messages: finding meaning in volcanic gases'. — Tehnuka presenting her ECR plenary, entitled ‘Un-mixing messages: finding meaning in volcanic gases’.

One of the pre-conference workshops was also tephra-related: ‘From field apps to data repositories: Improving tephra data discoverability, access, and workflows to support next generation research’, organised by Steven Kuehn, Kristi Wallace, Ellen Nelson, Andrei Kurbatov and Kerstin Lehnert. This workshop was a continuation of an ongoing project under the auspices of the Commission on Tephrochronology entitled ‘Community established best practice recommendations for tephra studies—from collection through analysis’, with a milestone paper published last year.

For a field visit and a chance to try out the Strabo app for field data collection, David, Josh, Richard, and Tehnuka arranged an excursion to a tephra outcrop at a nearby pumice quarry. The deposits here include the Rotorua and Waiohau tephras we are familiar with from lake coring around Hamilton, although they are much thicker, since this site is far closer to the source. Our field guide contains more details. Many thanks to the RNL pumice quarry owners for permission to visit.