Pyroclastic flows

Sato H., Eujii T., and Nakada S. (1992) Crumbling of dacite dome lava and generation of pyroclastic flows at Unzen volcano. Nature 360, 664-666. 

Wallace P.J., Dufek J., Anderson A.T., and Zhang Y. (2003) Cooling rates of Plinian-fall and pyroclastic-flow deposits in the Bishop Tuff inferences from water speciation in quartz-hosted glass inclusions. Bull. Volcanol. 65, 105-123. 

Tolfa-Manziana-Cerite 3.5 - Multicentre complex made of trachydacite to rhyolite lava flows, domes and pyroclastic flows. 

The Faete phase erupted about 6 km3 of volcanic products, which formed the Monte Faete lava and scoria cone, an intra-caldera massive pyroclastic flow deposit (Campi di Annibale pyroclastics), and some flank lava flows (Osa lava at 297 ka Capo di Bove lava at 277 ka Kamer et al. 2001 Marra et al. 2003). The activity of the Faete phase was closed by the collapse of the Campi di Annibale nested caldera and by circum-caldera strombolian eruptions. 

The final hydromagmatic phase occurred from several explosion craters mainly located in the western sector of the volcano, and produced about 1 km3 of pyroclastic surge, flow and lahar deposits and very few lavas. The best known explosion craters include the maars of Nemi and Albano lakes. The youngest measured age, obtained by thermoluminescence methods on wet pyroclastic flow deposits from the Albano crater, yields a date of about 19 ka (Voltaggio and Barbieri 1995 and references therein). 

The most important eruptive centres include the pyroclastic flows of Pa-trica and the cones of Tecchiena, Celletta, Colle Castellone, Borghetto, Pofi, Villa Santo Stefano and Giuliano di Roma. Most of these centres consist of mafic ultrapotassic rocks potassic and low potassic basalts occur at Villa Santo Stefano and in a few places south of Ceccano (Fig. 5.2). 

Potassic - ultrapotassic lavas [ Pyroclastic flows, surges, lahars J Pyroclastic fall deposits 1 Volcano-sedimentary deposits j Limestones I Carbonate deposits j Alluvial conglomerates J Sandstones and calcarenites... 

Influenced by pyroclastic flow after Mt. St. Helens eruption. 

Nakada, S. Fujii, T. 1993. Preliminary report on the activity at Unzen Volcano (Japan). November 1990-November 1991 dacite lava domes and pyroclastic flows. J Vol Geoth Res 54 pp.319-333. 

Formenti, Y. and Druitt, T.H. (2003) Vesicle connectivity in pyroclasts and implications for the fluidisation of fountain-collapse pyroclastic flows in Montserrat (West Indies), Earth Plan. Sci. Lett. 214, 561. 

Spence, R.J.S., Baxter, RJ. Zuccaro, G. 2004. Building vulnerability and human casualty estimation for a pyroclastic flow a model and its application to Vesuvius. Journal of Volcanology and Geothermal Research, 133, 321-343. doi http //dx.doi.org/10.1016/S0377-0273(03)00405-0. 

Among several volcanic phenomena (e.g. lava flows, pyroclastic flows, etc.) which can potentially affect inhabitants and buildings, the volcanic ash emission is the most significant, due to its large impact area. 

The gas gives the flow mobility, and their runout distance can be many km, much greater than a rockfall event. Pressurization within the dome is determined by the exsolution of volatiles, which in turn is partly controlled by the extrusion rate. At Volcan de Colima, pyroclastic flows were rare and only very small during the very slow dome growth that occurred between 2007 and 2011, whereas the faster effusion rate which was witnessed in 2004 resulted in frequent... 

A faster growth rate implies greater pressurization within the dome, which in turn increases the potential for far-reaching pyroclastic flow and hence far greater risks. Once a dome growing within the summit crater of a stratovolcano has reached the rim, it will begin to overflow in the form of rockfalls and possibly form a lava flow. 

Merapi in Indonesia deserves a special mention with its long history of frequent pyroclastic flow generation associated with the growth of a dome on the upper flanks. In 1994 a flow killed over 60 people, and it was thought to have been generated by pure gravitational collapse of the... 

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