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Please use this identifier to cite or link to this item: http://hdl.handle.net/2122/6641

Authors: Benson, P.*
Vinciguerra, S.*
Meredith, P.*
Young, P.*
Title: Spatio-temporal evolution of volcano seismicity: A laboratory study
Title of journal: Earth and Planetary Sciences Letters
Series/Report no.: /297(2010)
Publisher: Elsevier
Issue Date: 2010
DOI: 10.1016/j.epsl.2010.06.033
Keywords: volcano-tectonics, acoustic emission, rock physics, seismology, hazard
Abstract: We report a laboratory and microstructural study of a suite of deformation experiments in which basalt from Mount Etna volcano is deformed and fractured at an effective confining pressure representative of conditions under a volcanic edifice (40 MPa). Particular attention was paid to the formation of a fracture and damage zone with which to stimulate coupled hydro-mechanical interactions that create the various types of seismicity recorded on volcanic edifices, and which usually precede eruption. Location of AE events through time shows the formation of a fault plane during which waveforms exhibit the typical high frequency characteristics of volcano-tectonic (VT) earthquakes. We found that these VT earthquakes were particularly pronounced when generated using dry samples, compared to samples saturated with a pore fluid (water). VT events generated during deformation of water saturated sample are characterised by a distinctive high frequency onset and a longer, low frequency coda exhibiting properties often seen in the field as hybrid events. We present evidence that hybrid events are, in fact, the common type of volcanic seismic event with either VT or low frequency (LF) events representing end members, and whose proportion depend on pore fluid being present in the rock type being deformed, as well as how close the rock is to failure. We find a notable trend of reducing instances of hybrid events leading up to the failure stage in our experiments, suggesting that during this stage, the pore fluid present in the rock moves sufficiently quickly to provide a resonance, seen as a LF coda. Our data supports recent modeling and field studies that postulate that hybrid events generated in volcanic areas are likely to be generated through the interaction of hydrothermal fluids moving through a combination of pre-existing microcrack networks and larger faults, such as those we observe in forensic (post-test) examination.
Appears in Collections:04.06.08. Volcano seismology
04.08.06. Volcano monitoring
04.08.05. Volcanic rocks
05.02.02. Seismological data
Papers Published / Papers in press

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