PhD: Unravelling the long-term interplay between climate, volcanic activity, and earthquakes

Supervisors:

Lorna Strachan, University of Auckland, New Zealand
Helen Bostock, University of Queensland, Australia
Philip Barnes, National Institute of Water and Atmosphere, New Zealand
Katie Maier, National Institute of Water and Atmosphere Research, New Zealand
Mike Clare, National Oceanography Centre, UK
Joris Eggenhuisen, Utrecht University, Netherlands

Advisors:

Kathie Marsaglia, California State University Northridge, USA
Davide Gamboa, Instituto PortuguÍs do Mar e da Atmosfera, Portugal

Keywords: IODP, subduction, trench, stratigraphy, age model, gravity flows, turbidites, hemipelagite, contourite, mass transport complex, tephra, dating, core, bathymetry, machine learning, physical modelling, flume, NZ,

As part of a new project funded by the Royal Society of New Zealand, we are looking to recruit a PhD candidate (fully funded over 3 years at the University of Auckland) to lead the analysis of long-term sedimentary records in the deep-sea Hikurangi Trough and to become part of our wider international research team. Volcanic eruptions and earthquakes are major geohazards; hence, understanding their past frequency and whether that may change in future, is critical for disaster management planning. Previous studies have suggested that climatic and sea level changes may play a role in the nature and rate of these hazardous events, but remain inconclusive as a result of short duration records, which often only span the last glacial-interglacial transition and include too few event beds for meaningful statistical analysis. This PhD project will focus on the analysis of a long-term (800 kyr) sediment record on the Hikurangi margin that records event beds from numerous volcanic and earthquake events across multiple glacial-interglacial climate cycles. This exceptional record therefore allows us to investigate how climate influences the frequency of volcanic activity and earthquakes. This PhD project will contribute to a much larger research programme that brings together researchers from around the globe (NZ, Australia, UK, Germany, Netherlands, Portugal, US) with expertise in sedimentology, paleoseismology, volcanology, biostratigraphy, magnetostratigraphy and seismic interpretation.

The PhD project will use a high-resolution ~500 m-thick sediment record that was recovered at Hole U1520D in 2018 as part of International Ocean Discovery Program (IODP) Expedition 375. This core was located on the highly active Hikurangi Subduction Margin (HSM), New Zealand in order to quantify the frequency, nature and controls on earthquake and volcanic events, as recorded by tephra and turbidite deposits, over climatically-variable timescales. The quality of stratal preservation in the core is exceptional, recording many hundreds of tephra and turbidite horizons; thus enabling meaningful quantitative and statistical analyses to be performed.

The aim of the PhD is to determine how climatic changes over various timescales effects earthquake and volcanic events on the Hikurangi margin. Specific objectives will include:

  • Establish a comprehensive sedimentological framework for the upper 500 m of U1520 using granulometry, visual logging, facies analysis, physical property data (magnetic susceptibility, density, computed tomography) and geochemical data (XRF and ITRAX), as well as geostatistical methods.
  • Compare the nature and timing of deposits in the Holocene part of the sequence against established time histories of regional earthquakes and volcanic activity to develop diagnostic criteria for event bed identification in the longer record that can be linked to different trigger-types.
  • Apply the event deposit criteria to the pre-Holocene record to create a longer term record of volcanic and earthquake events over 800 kyr. Statistical analyses (e.g. proportional hazards, generalised linear and clustering models) will be used to determine temporal variations in event frequency, and to test for links or feedbacks with climate over glacial and interglacial cycles.
  • Conduct a series of physical flume experiments, using the Eurotank at Utrecht University to investigate the role and interplay of multiple gravity flow sources and bottom currents on deposit character, geometry and type, as an analogue for site U1520.

The student will join the Coastal and Marine Geoscience Group at Auckland, a vibrant community of postgraduate students, postdocs, and academics interested in a wide variety of physical processes from the coast to the deep abyss. While based at the University of Auckland, and dependant on future COVID restrictions, the student will spend time at the National Institute of Water and Atmosphere (NIWA) Research, located in Wellington, NZ, and have the opportunity to visit the IODP core store in Texas, USA, the Eurotank flume in Utrecht, Netherlands, and have regular opportunities to engage with the international advisory team.

Application

Applicants need to demonstrate a high level of sedimentological proficiency, an aptitude to work in a large team, and a willingness to learn new techniques. Individuals with an MSc are preferred. Exceptional BSc Honours graduates will also be considered. Once the candidate has been accepted to the PhD they can start at any point within the year. The project is open to all students (NZ and international). However there are currently some covid-related visa restrictions for international students, but pre-visa enrolments are possible.

CLOSING DATE: 7th of May, 2021

To apply, please send a Cover letter and CV to Lorna Strachan l.strachan@auckland.ac.nz

Further questions to Lorna Strachan l.strachan@auckland.ac.nz

posted: 14 April 2021     Please mention EARTHWORKS when responding to this advertisement.