Leighton Watson

Leighton Watson is a Senior Lecturer in Mathematics and Statistics at the University of Canterbury | Te Whare Wānanga o Waitaha.

My research focuses on how geophysical data (seismic and acoustic) can be combined with physics-based computational simulations to better monitor and understand natural hazards, with a particular emphasis on infrasound (low-frequency acoustic waves that are below the frequency limit of human hearing) and volcanic eruptions. Motivated by interesting observations of natural activity, a desire to reduce risk, and a strong scientific curiosity, I develop numerical models that are derived from fundamental physics. I validate these models by acquiring my own data, or by comparing with existing geophysical data and visual observations, and then use the validated models to learn about the behaviour of complex volcanic systems in order to improve monitoring efforts and hazard assessment.

My current areas of research include detecting and characterizing snow avalanches with infrasound, simulating geophysical signals from pyroclastic density currents, and infrasonic precursors to lava fountaining at open vent volcanoes.

I have also done work on the spread of COVID-19 in New Zealand | Aotearoa and economic analysis about the long-term financial impacts of unpaid placements on teachers, nurses, social workers, and midwives during long (3-4 years) and expensive degree programmes.

email: leighton.watson@canterbury.ac.nz

Current Research

Short-term pain for long-term gain? Financial implications of university fees and unpaid placements on workers in healthcare and education industries

Teaching, nursing, social work, and midwifery require multiple years of tertiary study, during which students work for free on unpaid placements while paying university fees. Midwives are the most extreme example; they need to do over a year of unpaid work while paying over $9000 per year in fees during their four-year degree. Dropout rates are up to 42% for midwifery and 45% for social work. Students in these fields are rewarded with higher salaries after graduation—but is it worth it?

We compared lifetime earnings for a worker in each profession and for someone working a minimum wage job. It takes more than eight years since starting to study for a nurse to make more money than the minimum wage worker and 12 years for a social worker. The short-term pain of working for free on restrictive placements while paying courses fees does have a long-term return—but it can take a very long time to realise that return.

Police and firefighters are also essential public service roles, but the training period is much shorter, trainees are paid, and dropout rates are less than 2%. Despite higher salaries, it takes 14 years since starting to study for nurses and an astounding 28 years for midwives to have higher total earnings over their working lifetime than police officers.

If we want to recruit and retain workers in essential education and healthcare services we need to rethink our education approach to reduce the short-term pain and improve the long-term gain.

For more details, see the research paper here.

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PYROCLASTIC DENSITY CURRENTS

Pyroclastic Density Currents (PDCs) are extremely hazardous flows of hot gas, ash, and rock. They are formed by the collapse of an eruption column or lava dome. PDCs are fast moving, can travel large distances, and are extremely devastating.

In this work, we simulate the flow dynamics of PDCs and calculate the acoustic and seismic signals generated by the flows. This will help monitoring efforts by improving our understanding of how PDC flow properties relate to the geophysical (acoustic and seismic) observed in the field.

COMPUTATIONAL AEROACOUSTICS

We perform simulations of volcanic eruptions using a computational aeroacoustics code. This enables us to solve for the flow dynamics as well as the associated infrasound signal, which is not commonly done. In this project, we explore how infrasound observations are influenced by complex flow dynamics and nonlinear effects in the near-vent region.

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INFRASONIC RESONANCE

Infrasound signals (low frequency acoustic waves in the atmosphere) are frequently excited by volcanic activity at open vent volcanoes. The character of the infrasound signal is modulated by the crater geometry. We investigate how the infrasound signal can be inverted for the crater geometry and lava lake depth. In particular, we examine changes in the observed infrasound signal can constrain (a) lava lake dynamics at Villarrica (Chile) and (b) crater collapse and draining of magma from the summit at Mount Etna (Italy).