Dr Vern Manville

Profile

Dr Vern Manville initially studied geology at St. Edmund Hall, Oxford, before beginning a PhD at the University of Otago in Dunedin, New Zealand, supported by a New Zealand Vice Chancellor's Committee and James Parke scholarships. In the interim he worked for British Petroleum Exploration in London for 6 months as a technical assistant. PhD studies were followed by a sub-contracted post-doctoral position with the Institute of Geological and Nuclear Sciences (now GNS Science), based at Wairakei near Taupo. The post-doctoral position turned into a full-time job where he worked on the 1995-96 and 2007 eruptions of Ruapehu, led GNS Science's scientific response to the March 2007 Crater Lake break-out lahar, and researched the aftermaths of large explosive eruptions from caldera volcanoes both in New Zealand and around the world. This culminated in the award of the Hochstetter Lectureship from the Geological Society of New Zealand, before he resigned from GNS Science in July 2009 to take up a teaching and research position in the School of Earth and Environment at the University of Leeds.

Responsibilities

• Fieldwork convenor GS PDT
• Module Manager SOEE2095/2096/2107/3073/5305M

Research interests

• Morpho-sedimentary responses to explosive volcanic eruptions
• Sedimentology of volcaniclastic deposits in continental and marine environments
• Lahar initiation and propagation processes, including debris- and hyperconcentrated flow rheology and physical and numerical modelling
• Debris avalanche initiation and run-out processes
• Coupled catchment-channel dynamics in perturbed Earth systems
• Dam-breach floods from natural impoundments, including volcanogenic lakes and landslide dams
• Volcano-tectonic interactions at caldera volcanoes
• Field teaching in undergraduate Earth science degree programmes

Current Projects

Landscapes impacted by explosive volcanism exhibit some of the highest sediment yields on Earth, where ambient drainage and sedimentary systems are overwhelmed by huge volumes of particulate material. The secondary volcanic hazards that arise from such events, including devastating rain-triggered lahars (volcanic mass-flows and floods) and the associated inundation and burial of infrastructure and land can impact areas far-removed from the volcano, which may have escaped primary hazards, and may persist for years to decades after the cessation of eruptive activity. Although we have a broad understanding of geomorphic and sedimentary responses to explosive volcanic activity in terms of patterns and chronologies of erosion, resedimentation, and aggradation thanks to seminal eruptions in the late 20th Century, more recent studies are focussed on deciphering the system- and catchment-specific controls that govern the style, severity and duration of the post-eruptive impacts.

Landscape reponses to the April 2015 eruption of Calbuco Volcano, southern Chile

The c. 0.31 km3 April 2015 eruption of Calbuco Volcano in southern Chile generated sub-Plinian eruption columns, multiple topographically confined pyroclastic density currents, and both hot and cold primary eruption-triggered lahars in many of the radial drainages that rise on the volcanic edifice. Fieldwork and remote-sensing analyses, focussed on three major catchments with differing physiography and hydrological regimes, which each received different volumes and proportions of tephra fall and pyroclastic flow material, highlight local nuances in the post-eruptive morpho-sedimentary response.

Overall, except where an internal impermeable crust developed, the majority of the coarse, dense tephra deposited by the 2015 eruption appears to have low remobilisation potential, suggesting that Calbuco lies close to the other end of the spectrum of post-volcanic landscape sensitivity to that shown by the 2008 Chaitén eruption. Each catchment has responded differently, as a function of drainage basin physiography, hydrology, and the volumes, characteristics and spatial distributions of pyroclastic material. In the Rio Blanco Este, the most heavily impacted catchment that lay under the tephra dispersal axis and also received extensive pyroclastic flows, major rain-triggered lahar activity was delayed until the first significant post-eruptive rainfall event in mid-May 2015. Up to 12 m of aggradation occurred within 6 months of the eruption as remobilised material translated downstream as a kinematic wave. Mid-term re-incision of this material has now however reversed, due to destabilisation of an additional large reservoir of pyroclastic material identified high on the mountain, following rainfall in January 2018 that apparently exceeded some stability threshold. Ongoing research is correlating the controls on the initial phase of response and tracking the longer term readjustment of the volcano-sedimentary system.

Strengthening REsilience in Volcanic Areas (STREVA)

STREVA brings together researchers from universities, research institutes and volcano observatories, to explore methods for reducing the negative consequences of volcanic activity on communities by working with both the communities that face volcanic threats and those responsible for monitoring, preparing for and responding to those threats. Project partners include volcano monitoring agencies and observatories in Colombia, the Caribbean and Ecuador, and through them, disaster managers and disaster researchers throughout the region. STREVA uses a number of techniques to build links between the project and the wider community, including workshops, running scenario exercises, and using social media to report results. By working collaboratively across disciplines, including the use of case studies, STREVA aims to develop and apply a risk assessment framework that will help communities to develop better risk mitigation plans that reduce exposure to volcanic hazards. The work will generate improvements in: (i) methods for forecasting the start of eruptions and changes in activity during eruptions; (ii) predictions of area at risk from different volcanic hazards; (iii) understanding of the factors that make people and their assets more vulnerable to volcanic threats; and (iv) understanding of institutional constraints and capacities and how to improve incentives for risk reduction. Practical results include strengthening the capacity of stakeholders at different scales (volcano observatories, local and national governments and NGOs) to produce robust risk assessments, improve preparedness and responses, and build resilience through long-term planning.

The 18 March 2007 break-out lahar from Crater Lake, Ruapehu, New Zealand

During a prolonged eruption sequence in 1995-96, the summit Crater Lake of Mt. Ruapehu, New Zealand was emptied and a barrier of tephra and blocks deposited over the former outlet area. Eleven years later, on 18 March 2007, the refilling warm acidic lake breached this fragile natural dam, resulting in the rapid release of over a million cubic metres of water in less than 2 hours. The torrent of water poured down the steep upper gorge of the Whangaehu River, quadrupling its original volume be entraining glacial ice, landslide debris, and older alluvium, before debouching onto a broad low-gradient ring-plain where it anastomosed. After crossing the ring-plain, the flood collected back into a single meandering channel incised into uplifted marine sediments, reaching the coast 200 km away 13 hours later. The foreseen nature of this event meant that maximum scientific information could be obtained by instrumenting the channel as if it were a giant laboratory flume to capture time-series data on key hydraulic parameters from the constantly evolving flow, including seismic proxies for sediment load and flow behaviour, using pre- and post-event airborne LiDAR surveys to map the flowpath and measure geometric changes with sub-metre accuracy, and observer teams to capture video footage and dip-samples, all backed up by traditional forensic sedimentology and the detailed logging and characterisation of deposits. Taken together, these constitute probably the most detailed dataset compiled on a single volcanogenic flood event anywhere in the world, and are already informing new numerical models of lahar behaviour under development by international collaborators.

Eruption-triggered lahars at Mount Ruapehu, New Zealand 

Eruptions beneath the summit Crater Lake of Mt. Ruapehu, New Zealand, eject jets of water and rock debris on ballistic trajectories. These impact the seasonally snow-covered upper slopes of the mountain and drain off, forming complex multiphase granular mass-flows dominated by entrained snow and ice. Over the past 150 years, these hazardous lahars have entered areas now occupied by major commercial skifields on at least 6 occasions at velocities of up to 80 km/hr. Current research is focussed on understanding new observations and insights obtained from the 25 September 2007 eruption of Ruapehu, coupled with unique video footage of flows generated early in the 1995-96 eruption sequence, with a view to developing probabilistic models of lahar risk and optimising mitigation strategies.

Qualifications

• BA (Hons), Geology, University of Oxford
• PhD, Geology, University of Otago

Professional memberships

• European Geophysical Union
• IAVCEI

Student education

I am currently the Fieldwork Convenor for the Geological Sciences programme in the core Programme Delivery Team. I have an oversight role on all undergraduate field-teaching across levels one through five, as well as contributing to numerous field classes in a leadership, co-teaching or advisory support capacity, including managing the independent geological mapping dissertation projects between levels two and three/five. In addition, I teach academic tutorials at all levels, and contribute to class room teaching in the areas of sedimentology, volcanic processes and geological map skills.

Research groups and institutes

• Institute of Applied Geoscience
• Sedimentology
• Volcanology
• Planetary Exploration