PDC transport dynamics – Benchmarking numerical models and future avenues

PDC transport dynamics – Benchmarking numerical models and future avenues

We are very happy to publish a report on a workshop held in January 2019 in New Zealand and co-supported by the IAVCEI Commission on Explosive Volcanism. 

Below you can find the report with a solicitation to submit papers for a Topical Collection on Bulletin of Volcanology, under the general heading of “Pyroclastic current benchmarking and validation”. 

CEV expresses its congratulations to the organizers and thanks them for their work.

PDC transport dynamics – Benchmarking numerical models and future avenues

Models of pyroclastic density currents (PDCs) are widely used for fundamental research as well as for hazard and risk modeling that supports decision-making and volcanic crisis management. Because of the high impact that the modeling and simulations can have, their credibility and adequacy need to be assessed by means of an established, consensual benchmarking and validation procedure.

Building upon earlier workshops in 2007 and 2013, a workshop entitled “PDC transport dynamics – Benchmarking numerical models and future avenues”, was held in January 2019 in Taupo, New Zealand, supported by the Royal Society of New Zealand Marsden Fund (MAU 1506), a Massey University International Visitor Grant (RM 21587), and the IAVCEI (International Association of Volcanology and Chemistry of the Earth Interior) Commission of Explosive Volcanism. The workshop was organized by Massey University (New Zealand) in collaboration with Istituto Nazionale di Geofisica e Vulcanologia (Pisa, Italy), and comprised an international group from 7 countries of about 20 experts in numerical and experimental (field and laboratory) modeling of pyroclastic currents.

The workshop objective was twofold: 1) to establish a consensual benchmarking and validation (B&V) process for models of pyroclastic currents, and 2) to propose a first, large-scale experimental benchmark case for numerical models, carried out at the PELE laboratory at Massey University, focusing on the dilute, turbulent end-member of PDCs.

Three days of scientific presentations were dedicated to both numerical and laboratory studies of PDCs, with focus on B&V. First examples of numerical simulation of the PELE large-scale experiments were discussed. As a necessary, complementary topic, key contributions from volcano field studies were presented, with emphasis on quantitative approaches and comparison with theoretical, laboratory and computational models.

The workshop was also the opportunity to experience in the field the different phenomenology of PDC emplacement. Field excursions were accompanied and welcomed by the Maori local community leaders, in the framework of a continuous effort of the NZ scientific and academic institutions to engage the native communities in volcanic hazard and risk assessment and for mutual cultural exchange and growth.

The first field-trip led the participants to the AD232 Taupo ignimbrite deposits, providing thought provoking evidences and questions about the transport and sedimentation mechanisms in large volume PDCs. In the second field trip at Te Maari crater of Tongariro volcano (which was the site of hydrothermal eruptions in 2012), participants had the opportunity to appreciate in the field the capability of a relatively small, high-energy, turbulent PDC generated by hydrothermal blasts to propagate over complex, rugged morphologies, crossing steep valleys and overcoming significant topographic obstacles. A third field trip was dedicated to the pyroclastic deposits of the 1975 Mount Ngauruhoe eruption, which can be classified at the opposite end-member of concentrated granular flows. A fruitful visit to the GNS Wairakei Research Centre allowed workshop participants to be informed and discuss about natural hazard and risk management in New Zealand.

Finally, the last day of the workshop was dedicated to running one large-scale experiment at the PELE laboratory, with focus on repeatability of results and collection of new data of infrasound signals generated by turbulent PDCs. The experiment was conducted successfully, thanks to the synergetic work of the experienced PELE team and the enthusiastic participation of the workshop attendees.

The excellent food, the ambiance and the wonderful view on the Taupo lake from the Tauhara retreat and conference center, provided the finishing touches for the great success of this workshop.

Gert Lube, Tomaso Esposti Ongaro, Matteo Cerminara, Ermanno Brosch

on behalf of the workshop participants:

Brittany Brand, Eric Breard, Eliza Calder, Sylvain Charbonnier, Joseph Dufek, Takeiro Koyaguchi, Ulrich Kueppers, Mie Ichihara, Michael Manga, Stuart Mead, Augusto Neri, Nick Pollock, Olivier Roche, Claudia Sanchez, Hiro Shimizu, Roberto Sulpizio, Greg Valentine