Our first meeting took place during the Cities on Volcanoes 3 conference in Hilo (Hawaii, July 2003). During this meeting we discussed goals #1 and #2, and how to proceed for goal #3 and #4 (as listed under Objectives).
The first meeting of the IAVCEI Working Group on Modeling Volcanic Tephra-Fall Hazards took place in Hilo (Hawaii) on July 2003 within the Cities on Volcanoes 3 conference. This first meeting was convened to bring together scientists with different tephra-fall hazard experiences in order to integrate and improve current approaches and tephra-dispersal models. It was open to everyone interested in tephra-fall hazard and therefore it involved computer modelers, model users and field volcanologists. The main issues that were identified during this first meeting are:
1) Development of a model calibration protocol to compare the results of numerical models with observations from well-characterized eruptions.
2) Identification of model parameters to develop a common understanding of model requirements, and appropriate data needs from characterized eruptions.
3) Discussion of well-characterized tephra fall eruptions that could be used to evaluate model accuracies. These eruptions need to have appropriate field or lab measurements to successfully parameterize the models.
4) Outline of a working-group webpage useful for computer modelers, model users and field volcanologists. This webpage will include: description of the working group, description of existing tephra-fall models with corresponding links, shared database of open-source codes and data to facilitate rapid development and use of dispersion models, protocol for tephra sampling and analysis.
5) Identification of specific hazards from tephra, needs of different organizations for hazards analyses (e.g., aircraft alerts, facilities designs, evacuation likelihoods), and appropriate models to meet these information needs.
6) Need to develop a standard protocol for tephra sampling and determination of deposit volume and total grain size distribution to make the studies of different deposits comparable. This sampling protocol should also provide data needed for input parameters for tephra-fall modeling.
7) Likely need to incorporate particle aggregation processes in models for tephra-dispersal.
8) Eventual integration of calibrated models into useable hazard analysis tools that can be widely distributed. This could be done within the MAPGAC program of the Geological Survey of Canada.
Our second meeting took place during the IAVCEI 2004 conference and was focused on the discussion of goals #5 and #6 (as listed under Objectives). In particular, it mainly focused on:
1) issues and improvements of datasets used for model calibration (mainly focusing on the 5 datasets gathered after the first meeting);
2) protocol for comparisons between field and computed data;
3) protocol for data collection relevant to tephra-fall modeling;
4) support by extramural funding for the development of a useable hazard analysis tool that can be widely distributed (e.g. Geological Survey of Canada and the Multinational Andean Project).
Conclusion of the meeting was that we have to focus on the collection of more “quality” data associated with large eruptions is needed (e.g. Pinatubo 1991, Mt Spurr 1992) and on the compilation of a tephra-sampling protocol in order to guarantee the quality of data.
Our third meeting was run as a 3-day pre-conference workshop associated with Cities on Volcanoes 4 in Quito (Ecuador, January 2006). During this last meeting we started working on the determination of crucial field parameters for the study of tephra deposits and their implications for tephra modeling. In particular, we focused on the determination of the “maximum clast”. Results of this meeting where presented and discussed during IAVCEI 2008 in Iceland (forth meeting). The final report can be downloaded from here and summarized in Bonadonna, Cioni, Pistolesi, Connor, Scollo, Pioli, Rosi (2013), Determination of the largest clast sizes of tephra deposits for the characterization of explosive volcanic eruptions: a study of the IAVCEI commission on tephra hazard modelling, Bullettin of volcanology, 75:680.
The fourth meeting was held as part of the IAVCEI General Assembly 2008 (17-22 August 2008, Reykjavik, Iceland) and mainly focused on:
1) Discussion of the results from the Commission field workshop on the determination of the maximum clast carried out in Ecuador (3rd meeting, Salcedo, 2006).
2) Publication of the results of the Ecuador workshop both as a short communication and as an IAVCEI official report (both peer reviewed).
3) Improving the data set of the IAVCEI Commission to include data from the following eruptions: Mt Spurr 1992 (Alaska), Fuego 1974 (Guatemala), El Chichon 1982 (Chile), Etna 2001 (Italy), Mt St Helens 1980 (USA).
4) When available, adding the web-site links of wind profiles to eruption data set.
5) Compilation of a software for the extrapolation of wind profiles above the volcanic vent.
6) Compilation a database for thresholds of hazardous tephra accumulation.
7) Make sure there is consistency between the sampling protocol of our Commission and the IVHHN.
8) Link and data sharing with other working groups (Eruption Source Parameters Group, International Volcanic Health Hazard Network) and IAVCEI Commissions (Statistics in Volcanology, Commission on Explosive Volcanism).
We have also discussed the possibility of carrying out sensitivity analyses both on field and modeling procedures:
9) Sensitivity analyses on the effects of the distribution and number of field data on the determination of eruptive parameters.
10) Modeling exercise to reproduce isopleth maps and compare them with the model of Carey and Sparks (1986).
11) Comparison of the outputs of different sedimentation models using the same initial conditions (i.e. same eruption parameters). Such a test is work in progress at Instituto Nazionale di Geofisica e Vulcanologia (Italy) using the following models: TEPHRA2, HAZMAP, FALL3D, PUFF and VOLCALPUFF; and scenarios: Etna 1998 and 2002.
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