Volcano Geophysics PhD Opportunity: Shallow crustal controls on monogenetic volcanism from multiparameter geophysical studies.

A PhD studentship at University of Auckland, funded by Devora (Determining Volcanic Risk for Auckland; http://www.devora.org.nz/), is available to investigate outstanding questions on two intraplate basaltic volcanic fields in New Zealand. These are the Auckland Volcanic Field (AVF) and the Whangarei Volcanic field (WVF), both in the northern North Island of New Zealand

At both the AVF and WVF the role of basement structure in controlling dyke ascent and final eruption location is poorly understood. Beneath the AVF the Mesozoic basement/Miocene Waitemata Group contact is a major physical property contrast that may affect the propagation of dykes towards the surface and act as an important control on the last critical stages of magma ascent to the surface, where a city of 1.5 million people is now located.

To test the hypothesis that the shallow crust influences individual volcano locations, the student will use a range of high resolution geophysical techniques to create a 3D model of the buried basement topography and subsurface structure, analyse relationships to the AVF vent locations and use this model to constrain conditions that could allow rising magma to stall or laterally migrate at the basement or other interface. They will explore the implications of the model for volcano monitoring of the AVF and for general seismic hazard in Auckland.

At the WVF the same basement rocks that are beneath the AVF are exposed, allowing direct assessment of basement fault structures and volcanism. The student will geophysically study the mechanics of basement faulting and volcanism and determine if a generic faulting/vent location model exists that can be applied to both the WVF and AVF, considering local stress conditions at each field.

The 2nd aspect of the studentship will resolve outstanding questions around the youngest and largest volcano in the AVF. Rangitoto is anomalously large volume, and recent dating suggests multiple eruptions over 1500 years. Are there shallow crustal controls on the location of Rangitoto that have focussed magma repeatedly to the same location? Is Rangitoto really one volcano, or coincidently just multiple overlapping centers? Answering these questions requires an understanding of the internal architecture of the volcano, which the student will study using high resolution geophysical methods, from which a model of the evolution of the volcano will be derived.

The project will be supervised by Dr Jennifer Eccles at School of Environment, University of Auckland, and Dr Craig Miller at GNS Science. There will be opportunity to work both at the School of Environment, University of Auckland (Auckland) and GNS Science (Taupo).

The successful student will have good geophysical knowledge in potential field methods as well as a solid geological or volcanological background. Strong maths, coding (preferably python) and English language skills are required. A minimum of a 4 or 5-year geoscience degree is a prerequisite (good BSc Honours or MSc). The project will involve substantial field work so good fitness and logistical organisation skills are essential. Geophysical modelling will use open source (SimPEG) and proprietary codes (Geosoft Oasis Montaj, GM-SYS). Some aeromagnetic and variable spatial density gravity data exist over the AVF and WVF. Geophysical equipment available to support further data acquisition includes La Coste and Romberg gravity meters, magnetometers, resistivity imaging equipment and shallow, high resolution seismic reflection equipment. Potential field data and techniques will be pivotal to the project.

The PhD is funded for 3 years and includes a full studentship including fees plus $27k NZD annual stipend. The student will be awarded a degree from the University of Auckland (https://www.auckland.ac.nz/).

Please send expressions of interest including a cover letter, CV and transcripts to Jennifer Eccles j.eccles@auckland.ac.nz and Craig Miller c.miller@gns.cri.nz

posted: 26 March 2019     Please mention EARTHWORKS when responding to this advertisement.