Page 115 - Caldera Volcanism Analysis, Modelling and Response

90 Roberto Sulpizio and Pierfrancesco Dellino

1993; Neri et al., 2003). These computations have yielded invaluable constraints to
the basic physical processes that characterize motion and deposition of particles
within a PDC, but some complexities of natural currents are still difficult to
replicate using the available computational capabilities. The addition of new results
and constraints from field data and experiments into numerical codes is the main
challenge for future research in numerical modelling. Although recent develop-
ments in multiphase, Lagrangian codes represent a significant improvement toward
description of complex phenomena, the results are still not able to fully describe the
variability of natural PDCs.

ACKNOWLEDGEMENTS

This work is part of the ongoing research on explosive activity of Italian volcanoes funded by
Dipartimento di Protezione Civile (DPC-INGV projects 2005–2007). We gratefully acknowledge
Allison Austin for the revision of the English text. Many thanks to Jo Gottsmann for his editorial
assistance and to an anonymous reviewer for valuable suggestions.

REFERENCES

Alidibirov, M.A., Dingwell, D.B., 2000. Three fragmentation mechanisms for highly viscous magma
under rapid decompression. J. Volcanol. Geotherm. Res., 100, 413–421.
Allen, S.R., Cas, R.A.F., 1998. Rhyolitic fallout and pyroclastic density current deposits from a
phreatoplinian eruption in the eastern Aegean Sea, Greece. J. Volcanol. Geotherm. Res., 86,
219–251.
Baer, E.M., Fisher, R.V., Fuller, M., Valentine, G., 1997. Turbulent transport and deposition of the Ito
pyroclastic flow: determinations using anisotropy of magnetic susceptibility. J. Geophys. Res.,
102(B10), 22565–22586.
Bagnold, R.A., 1954. Experiments on a gravity-free dispersion of large solid spheres in a Newtonian
fluid under shear. Proc. Royal Soc., London, A, 225, 49–63.
Baxter, P.T., Neri, A., Todesco, M., 1998. Physical modeling and human survival in pyroclastic flows.
Nat. Hazard., 17, 163–176.
Bonnecaze, R.T., Huppert, H.E., Lister, J.R., 1993. Particle driven gravity currents. J. Fluid Mech.,
250, 339–369.
Branney, M.J., Kokelaar, P., 1992. A reappraisal of ignimbrite emplacement: progressive aggradation
and changes from particulate to non-particulate flow during emplacement of high-grade
ignimbrite. Bull. Volcanol., 54, 504–520.
Branney, M.J., Kokelaar, P., 1997. Giant bed from a sustained catastrophic density current flowing
over topography: Acatlan ignimbrite, Mexico. Geology, 25, 115–118.
Branney, M.J., Kokelaar, P., 2002. Pyroclastic Density Currents and the Sedimentation of Ignimbrites.
Geological Society, London, Memoirs, 27, 143 pp.
Brennen, C.E., Sieck, K., Paslasky, J., 1983. Hydraulic jumps in granular material flow. Powd.
Technol., 35, 31–37.
Bryan, S.E., Cas, R.A., Marti, J., 1998. Lithic breccias in intermediate volume phonolitic ignimbrites,
Tenerife (Canary Islands). Constraints on pyroclastic flow depositional processes. J. Volcanol.
Geotherm. Res., 81, 269–296.
Burgissier, A., Bergantz, G.W., 2002. Reconciling pyroclastic flow and surge: the multiphase physics
of pyroclastic density currents. Earth Plan. Sci. Lett., 202, 405–418.