Numerical simulations of block-and-ash flows using the Titan2D flow model: examples from the 2006 eruption of Merapi Volcano, Java, Indonesia

Abstract

We present Titan2D simulations of two wellcharacterized block-and-ash flow (BAF)

Aplicación de modelos numéricos de "aguas someras" para el análisis de peligros de flujos volcánicos: El caso de Titan2D y volcán Turrialba (Costa Rica)

“…Titan2D takes user inputs of an internal and bed friction, initial velocity, and starting geometry parameters (which can include a mass flux). Basal friction angles can also be supplied by using a 'material map', a raster containing friction values (e.g., Stinton et al, 2004;Charbonnier & Gertisser, 2009, 2012. Model outputs include flow inundation, thickness, and velocity.…”

“…In terms of strong internal shocks, the full Coulomb models are able to reproduce complex features of granular flows (Gray et al, 2003), such as the shocks themselves and "dead zones" where particles come to rest and accumulate. Comparisons of numerical implementations of Coulomb models with natural pyroclastic flows have also shown some success (e.g., Pitman et al, 2003;Rupp et al, 2006;Macias et al, 2008;Ogburn, 2008;Ogburn et al, in press;Charbonnier & Gertisser, 2009, 2012.…”

“…Using H/L vs. volume curves works well for simple channels, and provides a range of reasonable basal friction angles. For more complex terrain, 'calibrating' Titan2D by replicating natural deposits through trial and error, or employing material maps of varying friction may be required (Stinton et al, 2004;Charbonnier & Gertisser, 2009, 2012. Material maps can account for changes in roughness due to substrate type (Table 2).…”

“…The values of the friction angles chosen represent typical values used in studies of the runout of block-and-ash flows (e.g., Ogburn et al in press;Charbonnier & Gertisser, 2009, 2012. The first two examples have an internal friction angle (i.f.a) of 30 degrees, whereas the bed friction angles (b.f.a.)…”

“…Applications of these models have been used for block-andash flows at several volcanoes including Colima, El Chichon and Nevado de Toluca volcanoes in Mexico Patra et al, 2005;Saucedo et al, 2005;Rupp et al, 2006;Macias et al, 2008;Sulpizio et al, 2010); Mount Taranaki, New Zealand (Procter et al, 2010); Tungurahua, Ecuador (Kelfoun et al, 2009); Galeras and El Chichon Volcano, Columbia (Stefanescu et al, 2009;Murcia et al, 2010); Arenal Volcano, Costa Rica (Berrocal & Malavassi, 2006); Soufrière Hills Volcano, Montserrat (Hidayat et al, 2007;Ogburn, 2008;Ogburn et al, in press); and Merapi Volcano, Indonesia (Itoh, 2000;Charbonnier & Gertisser, 2009, 2012.…”