Analysis of source characteristics of experimental gas burst and fragmentation explosions generated by rapid decompression of volcanic rocks

• Published in: Journal of geophysical research. Solid earth 2015-07, Vol.120 (7), p.5104-5116
• Main Authors: Arciniega-Ceballos, A., Alatorre-Ibargüengoitia, M., Scheu, B., Dingwell, D. B.
• Format: Article
• Language: English
• Subjects: Autoclaving; Bursting; Conduits; Correlation; Decompression; Distribution; Dynamics; Energy; Energy consumption; Energy distribution; Eruptions; Explosions; Forces (mechanics); Fragmentation; fragmentation explosions; Gases; Geophysics; Microseisms; Monitoring; Parameters; Partitioning; Popocatépetl; Potential energy; Pressure; Properties; Pumice; Rheological properties; Rocks; Sequencing; source characteristics of explosions; Volcanic activity; Volcanic eruptions; volcanic explosion; Volcanic gases; Volcanic rocks; Volcanoes
• ISSN: 2169-9313; 2169-9356
• DOI: 10.1002/2014JB011810

Gas burst and fragmentation explosions induced by rapid decompression of volcanic rocks in a high‐pressure autoclave have been analyzed. We performed experiments from 4 to 20 MPa on (1) loose pyroclasts and (2) pumice from recent eruptions of Popocatépetl volcano. Our aim is to characterize the source mechanism distinguishing the physical processes that operate in the conduit which determine the dynamics of explosive volcanoes. For this aim we have analyzed experimentally the parameters that indicate the state and behavior of the conduit (i.e., decompression time, fragmentation threshold and speed, forces, and the partitioning of energy), using microseismic monitoring, the decompression time curves, and the sample rheological properties. The initial available potential energy in the system and its partitioning into different types of energies are correlated in space and time with specific stages of the explosive phenomenon. Such correlations, taken together with the energy distribution, enable the distinction of the individual physical processes involved and their causal sequence and relationships. Our observations suggest that in volcanic conduits with regular explosive activity, a source mechanism may operate whereby a causal sequence of processes results in a system that undergoes both rapid and stable transitions. Such behavior may persist over long periods of time. Key Points Characteristic parameters of gas burst and fragmentation explosions Causal sequence of processes account for nondestructive source mechanism Balanced internal conduit conditions allow a wide range of eruptive behaviors