IAP-24-120

Plinian eruption deposits from Las Cañadas Caldera, Tenerife: constraining eruption frequencies, eruption cycles and the Quaternary evolution of the island

The tephra record from a volcano is the most valuable resource in understanding when, how and why a volcano might erupt in the future. Understanding the frequency, location and nature of eruptions relies on building an as-complete-as-possible understanding of a volcano’s past behaviour, but this is often stymied by lack of exposure, erosion, and burial of past deposits.
Tenerife is a premier European holiday destination and hosts Las Cañadas volcano – a large silicic pyroclastic shield volcano topped by Las Cañadas Caldera. The caldera has had a protracted eruptive history stretching back 2 Ma. The flanks of the island and the caldera wall preserve the deposits of Plinian pumice fall deposits and ignimbrites (Brown et al., 2003; Edgar et al., 2007; Davila Harris et al., 2023) interspersed with innumerable lava flows erupted from vents within the caldera and the flanks of the volcano. Explosive eruptions are apparently clustered through time into 3 eruptive cycles (Ucanca, Guajara and Diego Hernandez Formations) (Martí et al., 1994), but despite numerous stratigraphic studies (Bryan et al., 1998; Brown et al., 2003; Edgar et al., 2017; Campbell, 2021; Davila Harris et al., 2023), ongoing fieldwork continually uncovers previously unknown Plinian eruption deposits across the island. This indicates that the stratigraphic record is still substantially incomplete. Additionally, correlations between proximal deposits in the caldera wall and distal deposits on the lower coastal flanks are unconstrained for large parts of the volcano’s history. Our understanding of the volcanic history of Las Cañadas caldera is still evolving and therefore so is our understanding of its future.

This project will provide new field constraints on the eruptive history of Las Cañadas Caldera and integrate these with the results of published and ongoing work. The student will undertake comprehensive fieldwork to hunt down previously unknown outcrops and volcanic deposits in the gullies and valleys of Tenerife. These deposits will be physically characterised (‘finger-printed’) in the field and the laboratory. Recent studies indicate that the palaeosols and sedimentary deposits between the pumice fall deposits contain evidence for cryptic eruptions – eruptions whose deposits have been either completely eroded from the island or completely weathered to soils. The student will investigate methods for extracting information on these ‘ghost’ eruptions. Concomitant with this will be the production of a new geological map that utilises the pumice fall deposits and tephro-chronological markers, to help understand spatial and temporal distribution of effusive eruptions and their products on the island. This will enable a reinvestigation of the Quaternary evolution of the caldera and the island. The ultimate aim is to exhaust the terrestrial record of explosive volcanism on Tenerife, use these data to improve determinations of the past frequency of explosive eruptions on the island, test models of eruption cyclicity and improve forecasts for future explosive eruptions.
During their tenure, the student will work closely with local science organisations on the island. They will spend time at the Instituto Geográfico Nacional (IGN) using the results of the fieldwork to improve understanding of the island’s volcanic evolution and help translate this information into an improved eruption scenarios. The student will also work with experts in science communication at GeoTenerife and present the results of their research to local communities via public talks and short videos. The project has the potential to take advantage of UK government-funded schemes to obtain 40Ar/39Ar dates for key eruptions.

Year 1

The student will undertake immersive desk-based research to familiarise themselves with the volcanology of Tenerife and initiate desk-based geologic mapping of the flanks of the island using satellite imagery and GIS software (Google Earth, and ArcGIS Pro). They will then undertake an extensive fieldwork campaign aimed at largely unexplored areas of the island (deep ravines and upper flanks) to uncover new outcrops of Plinian pumice fall deposits and integrate these with the existing stratigraphic frameworks. This nascent geological map will be ground-truthed by fieldwork including the use of photography and videography from UAVs. Detailed physical characterisation of juvenile material to enable correlation across the island. The student will spend time local science organisations and start planning outreach projects.

Year 2

Year 2 will start with laboratory characterisation of pyroclastic deposits (granulometry, componentry) followed by a second fieldwork season fieldwork involving geologic mapping, physical characterisation of caldera wall deposits, and integration with existing stratigraphic studies. Student will visit IGN and GeoTenerife to help translate their research into improved eruption scenarios and develop and execute outreach and science communication projects with GeoTenerife.

Year 3

Year 3 will start with fieldwork to complete the exploration and mapping of the flanks of the volcano. The student will integrate the results of geological mapping and stratigraphic studies with published data to produce a revised model for the physical and temporal evolution of Las Cañadas Volcano, and to revise estimates of the frequency of Plinian eruptions over time. They will draft scientific papers and present their results at an international conference.

Year 3.5

Drafting of thesis and submission of scientific papers.

The student will receive training in:

• Field and laboratory investigations of pyroclastic deposits (sedimentological mapping, isopach and isopleth maps, particle size distributions and componentry).
• Geological mapping of complex volcanic terrains.
• UAV surveys and structure from motion (SfM) terrain reconstruction techniques.
• Science outreach, public speaking and science communication.
• Verbal and written communication skills, preparation of scientific papers.

The student would join an active and diverse volcanology research group at Durham University staffed by experts in a wide range of volcanological disciplines. The research group provides additional support and training for post-graduate students. Fieldwork on Tenerife can be physically demanding and requires ascent and descent over steep, rough ground in a hot climate. Fluency in Spanish, or a willingness to learn will be strongly beneficial to the project. A driving licence is essential and demonstrated competence and willingness to drive abroad is essential. This would suit a student with a taste for adventure and a flexible and motivated approach to work.