What factors control superficial lava dome explosivity?

Abstract

Dome-forming eruption is a frequent eruptive style and a major hazard on numerous volcanoes worldwide. Lava domes are built by slow extrusion of degassed, viscous magma and may be destroyed by gravitational collapse or explosion. The triggering of lava dome explosions is poorly understood: here we propose a new model of superficial lava-dome explosivity based upon a textural and geochemical study (vesicularity, microcrystallinity, cristobalite distribution, residual water contents, crystal transit times) of clasts produced by key eruptions. Superficial explosion of a growing lava dome may be promoted through porosity reduction caused by both vesicle flattening due to gas escape and syn-eruptive cristobalite precipitation. Both processes generate an impermeable and rigid carapace allowing overpressurisation of the inner parts of the lava dome by the rapid input of vesiculated magma batches. The relative thickness of the cristobalite-rich carapace is an inverse function of the external lava dome surface area. Explosive activity is thus more likely to occur at the onset of lava dome extrusion, in agreement with observations, as the likelihood of superficial lava dome explosions depends inversely on lava dome volume. This new result is of interest for the whole volcanological community and for risk management.

Time Dependence of Passive Degassing at Volcán Popocatépetl, Mexico, From Infrared Measurements: Implications for Gas Pressure Distribution and Lava Dome Stability

“…This is further enhanced by the periodic pulsing of gas pressure within the dome's pore space and likely pushes longer‐term variations in dome gas flow toward the development of large overpressures which may induce dome destruction. These relationships may explain observations of rapid cycling of lava dome growth and destruction at the onset of such eruptive periods as noted by Boudon et al (). In this period, gas flux is generally high and lava domes relatively small, yielding the appropriate combination of values in the dimensionless parameter β . Because of system nonlinearity, the difference between pore pressure and load (effective tension) causes formation of a highly pressurized, shallow layer near the outer surface of the dome, which may be easily destabilized, resulting in failure and possibly explosive decompression, as proposed by Woods et al ().…”

“…This is further enhanced by the periodic pulsing of gas pressure within the dome's pore space and likely pushes longer-term variations in dome gas flow toward the development of large overpressures which may induce dome destruction. These relationships may explain observations of rapid cycling of lava dome growth and destruction at the onset of such eruptive periods as noted by Boudon et al (2015). In this period, gas flux is generally high and lava domes relatively small, yielding the appropriate combination of values in the dimensionless parameter .…”

K-Ar Age of Agua de la Piedra Volcanic Complex at Puesto Suárez, Río Negro

“…Las propiedades reológicas que manifiestan ambos sectores se corresponden con un núcleo caracterizado por deformación dúctil (importantes evidencias de flujo, plegamientos y corrugaciones) y una corteza con deformación frágil (brechamiento y textura lajosa). En general esta última puede ser una capa relativamente permeable a través de la cual se produce desgasificación (calder et al, 2015) y explicaría la presencia de cristobalita sineruptiva en los sectores externos del domo, donde además la disminución de la vesicularidad es mayor por escape de gases (Boudon et al, 2015) y propiciaría la formación de las lentícu-las de vidrio que interpretamos como relictos de fragmentos pumíceos. Las evidencias petrológicas indican que estas rocas podrían integrar una secuencia de diferenciación a través de procesos de cámara como cristalización fraccionada que están siendo evaluados en un conjunto de datos analíticos más amplio que incluyen rocas básicas e información isotópica.…”

Behavior Proportion According to Merapi Volcano Eruption Evacuations in 2010

“…Mount Merapi is classified into basaltic-andesitic strato volcano and lava dome [1,2,3,4], it means that Mount Merapi is a conical volcano with a rough circular mound-shaped protrusion as result of slow extrusion of lava and may be destroyed by gravitational collapse or explosion, the collapse of lava dome can generate pyroclastic flows or nuées ardentes [5,6]. Mount Merapi is the most active volcano in Indonesia [2] as well as one of the most active volcanoes in the world [7,8,9].…”