METEOR: Volcanic Ashfall Hazard footprints for Rungwe Volcano, Tanzania - Volcanic Explosivity Index (VEI): VEI 2 and VEI 4

Data Description

Volcanic Ashfall Hazard footprint for Rungwe Volcano, Tanzania.

Probabilistic ash fall hazard footprints have been produced for a VEI (Volcanic Explosivity Index, Newhall & Self, 1982) eruption scenarios of VEI 2 (relatively small) and VEI 4 (explosive) at Rungwe Volcano.

Rungwe volcano in Southern Tanzania was chosen as it is one of the better-studied volcanoes in Tanzania, with a record of at least seven explosive eruptions within the last approximately 4000 years, including VEI 4 and 5 eruptions at approximately 2000 and 4000 year before present (yrs BP), respectively (Fontijn et al., 2010; Fontijn et al., 2011).

Ash fall hazard footprints were generated using TephraProb, a freely available Matlab package developed to produce probabilistic hazard assessments for tephra fallout (Biass et al., 2016). TephraProb uses the Tephra2 tephra dispersion model. Tephra2 is an open source advection-diffusion model based on the work of Suzuki (1983) that describes diffusion, transport and sedimentation of tephra (ash) particles released from an eruption column (Connor et al., 2001; Bonadonna et al., 2005).  It calculates the total mass per unit area (kg m^-2) of tephra accumulation at individual grid locations by solving a simplified mass conservation equation.  The mass conservation equation takes into account the distribution of tephra mass in the eruption column and particle settling velocity, as well as horizontal diffusion within the eruption column and atmosphere after the particle has been ejected from the plume (Connor et al., 2001; Bonadonna et al., 2005; Connor & Connor, 2006).  Eruption parameters are assumed to represent average conditions over the duration of the complete eruption (Connor & Connor, 2006).

TephraProb can be downloaded from here: https://github.com/e5k/TephraProb

The Tephra2 source code can be downloaded from here: https://github.com/geoscience-community-codes/tephra2

Model input parameters set: total erupted mass, eruption column height, eruption duration, grain size distribution, eddy constant, diffusion coefficient, fall time threshold, particle density, integration step, plume model and wind (prevalent wind direction for Rungwe Volcano from ECMWF data (10-year window) is shown in ECMWF_10yr_wind_rose_month.jpg) and segretated into wet season (April-November) and dry season (December-March). 

For full details on the modelling, please refer to Winson et al. (2019)

Data Producer Attribution

BGS UKRI

Project Attribution

The data was generated by BGS as part of the Modelling Exposure Through Earth Observation Routines (METEOR): EO-based Exposure, Nepal and Tanzania project, a £2.8m project co-funded through the UK Space Agency’s International Partnership Programme (IPP) Call 2 as part of the Global Challenges Research Fund (GCRF) from the UK Government’s Official Development Assistance (ODA) commitment.

Data Format

GeoTIFF

Data Visualisation

GIS software. Suggest using suitable colour ramp for probability exceedance for the data range 0 (low) - 1 (high)

Spatial Resolution

1000m

Geographic Coordinate Reference System

WGS 1984 UTM Zone 36S (EPSG:32736)

Referenced Open Access Academic Papers

Biass, S., Bonadonna, C., Connor, L. & Connor, C. (2016) TephraProb: a Matlab package for probabilistic hazard assessments of tephra fallout. Journal of Applied Volcanology, 5, 10, 16pp. https://doi.org/10.1186/s13617-016-0050-5

Bonadonna, C., Connor, C.B., Houghton, B.F., Connor, L., Byrne, M., Laing, A. & Hincks, T.K. (2005) Probabilistic modelling of tephra dispersal: Hazard assessment of a multiphase rhyolitic eruption at Tarawera, New Zealand. Journal of Geophysical Research, 110, B03203, 21pp. https://doi.org/10.1029/2003JB002896

Connor, C.B., Hill, B.E., Winfrey, B., Franklin, N.M. & La Femina, P.C. (2001) Estimation of volcanic hazards from tephra fallout. Natural Hazards Review, 2, pp33-42. https://doi.org/10.1061/(ASCE)1527-6988(2001)2:1(33)

Connor, L.J. & Connor, C.B. (2006) Inversion is the key to dispersion: Understanding eruption dynamics by inverting tephra fallout. In: Mader, H.M., Coles, S.G., Connor, C.B. & Connor, L.J. (eds.) Statistics in Volcanology. Special publications of IAVCEI, London Geological Society, pp231-242. https://doi.org/10.1144/IAVCEI001.18

Fontijn, K., Ernst, G.G., Bonadonna, C., Elburg, M.A., Mbede, E. & Jacobs, P. (2011) The~ 4-ka Rungwe Pumice (South-Western Tanzania): a wind-still Plinian eruption. Bulletin of Volcanology, 73, pp1353-1368. https://doi.org/10.1007/s00445-011-0486-8

Fontijn, K., Ernst, G.G., Elburg, M.A., Williamson, D., Abdallah, E., Kwelwa, S., Mbede, E. & Jacobs, P. (2010) Holocene explosive eruptions in the Rungwe Volcanic Province, Tanzania. Journal of Volcanology and Geothermal Research, 196, pp91-110. https://doi.org/10.1016/j.jvolgeores.2010.07.021 

Newhall, C.G. & Self, S. (1982) The volcanic explosivity index (VEI): an estimate of explosive magnitude for historical volcanism. Journal of Geophysical Research, 87, pp 1231-1238 https://doi.org/10.1029/JC087iC02p01231

Suzuki, T. (1983) A theoretical model for the dispersion of tephra. In: Shimozuru, D. & Yokoyama, I. (eds.) Arc Volcanism, Physics and Tectonics. Tokyo, Terra Scientific Publishing,, 113,  pp95-113

Winson, A.E.G., Crummy, J., Mee, K., Boon, D., Ciurean, R., Dashwood, C., Garcia-Bajo, M., Sampson, C., & Silva, V. (2019) METEOR : hazard footprints for Nepal and Tanzania. Report M6.1/P. Nottingham, UK, British Geological Survey, 126pp. (OR/19/066) https://nora.nerc.ac.uk/id/eprint/534305/ 

Contact

kmcm@bgs.ac.uk