The flow dynamics of an extremely large volume pyroclastic flow, the 2.08-Ma Cerro Galán Ignimbrite, NW Argentina, and comparison with other flow types

Abstract

The 2.08-Ma Cerro Galán Ignimbrite (CGI) represents a >630-km 3 dense rock equivalent (VEI 8) eruption from the long-lived Cerro Galán magma system (∼6 Ma). It is a crystal-rich (35-60%), pumice (<10% generally) and lithic-poor (<5% generally) rhyodacitic ignimbrite, lacking a preceding plinian fallout deposit.

Evaluating the impacts of volcanic eruptions using RiskScape

“…These are extremely damaging fast-moving (10s to 100s of km/h; Lube et al, 2007;Cas et al, 2011;Komorowski et al, 2013;Roche, 2015), often quite hot flows (>100°C, generally 300-700°C) typically formed from volcanic column collapse or lava dome collapse (Dufek et al, 2015). Damage to the built environment is driven by dynamic pressure, P dyn (Spence et al, 2004;Jenkins et al, 2014a), which is a function of flow density, ρ, and velocity, v (Valentine, 1998):…”

Mecanismos eruptivos y procesos depositacionales del Grupo Choiyoi en el área de Las Caletas, Cordillera Frontal de San Juan, Argentina

“…Como lo sugieren Smith y Cole (1997) y Branney et al (1992), columnas eruptivas bajas tales como las de tipo 'boiling-over' pierden menos calor por mezcla con aire atmosférico en comparación con columnas plininas altas y la temperatura se mantiene elevada en los resultantes flujos piroclásticos. Muchas de las características mencionadas son semejantes a las que se presentan en las ignimbritas asociadas a las calderas de la Puna Guzmán y Petrinovic, 2010;Cas et al, 2011).…”

Dynamical weakening of pyroclastic flows by mechanical vibrations

“…These observations, together with lab-scale experiments, indicate that the main factor in driving sustained fluidization is long-lived gas *e-mail: jmillan@us.es pore pressure presumably due to hampered diffusion by the reduced permeability of the trapped gas through large amounts of fine ash [5]. (2) aluminium shaft, (3) flexible coupling (cardan), (4) step motor and controller, (5) vibrator (Tira TV 52120), (6) accelerometer, (7) halogen lamp, (8) CCD camera, (9) optical antivibration table, (10) desktop computer, (11) oscilloscope, (12) power amplifier, ( 13) function generator.…”

“…These dense granular flows are chiefly characterized by their high mobility. Usually, extraordinary long runout distances over 100 km and across topographic obstacles are reached [2][3][4][5]. A possible mechanism responsible for such astonishing behavior is sustained fluidization caused by the enhancement of pore gas pressure [2,5].…”

“…Usually, extraordinary long runout distances over 100 km and across topographic obstacles are reached [2][3][4][5]. A possible mechanism responsible for such astonishing behavior is sustained fluidization caused by the enhancement of pore gas pressure [2,5]. Since pyroclastic flows commonly contain large amounts of fine ash and light pumice rock fragments, their flow dynamics could be indeed determined by the prevalence of the interstitial gas drag force on the particles over their weight.…”