HR: 1340h
AN: V53C-1418    [Abstracts]
TI: Melt flow in a conduit and seismic signals time evolution: a laboratory study
AU: * Vinciguerra, S
EM: vinciguerra@ingv.it
AF: HP-HT Laboratory, Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Roma1, Via di Vigna Murata 605, Rome, 00143, Italy
AU: Caricchi, L
EM: luca.caricchi@erdw.ethz.ch
AF: Institute for Mineralogy and Petrology, ETH, Clausiusstrasse 25, Zurich, 8092, Switzerland
AU: Burlini, L
EM: luigi.burlini@erdw.ethz.ch
AF: Institute of Geology, ETH, Leonhardstrasse 19 LEB, Zurich, 8092, Switzerland
AB: A variety of seismic signals have been related to fracturing and magma transport in the volcanic edifice. Previous studies have provided a first experimental support to this association by reproducing fluid generation and migration while recording seismic signals in a layered sample comprising an olivine-MORB-olivine sandwich. Here, we developed a new experimental set up, consisting in a melt reservoir beneath a volcanic conduit, which allowed a much better control on the physical mechanisms taking place and the related seismic signals. Experiments up to 1373K and 300MPa confining pressure were carried out using an internally-heated Paterson gas apparatus especially designed for the measurements of physical properties of rocks. Acoustic emissions were measured during heating of cold pressed synthetic aggregate of MORB powder till complete melting. High frequency events were recorded at 750-960K, corresponding to glass transitions in the MORB glass (Giordano and Dingwell, 2003). A long lasting low frequency event took place at 1200K, corresponding to melt migration in the conduit, followed by high frequency events, related to brittle intrusive mechanisms due to the magma intrusion in the brittle medium at the top of the conduit. Experiments were also carried out on higher (Ĕ2 order of magnitudes) viscosities aggregates of Fish canyon tuffs, and varying the length of the conduit (from 3 to 15mm). Results highlight the seismic features related to the intrusion of the silicic magma in the conduit. Repeated occurrence both of swarms of high frequency events and long lasting signals at 500-1000K took place, followed from episodes of steady long lasting events at 1000-1273K. A direct relationship between seismic waveforms + spectrograms and physical phenomena can be assessed, by scaling length and frequency. These evidences provide solid and well constrained new experimental insight into magma migration in the lithosphere and the mechanism of dyke emplacement in volcanic edifices
DE: 5102 Acoustic properties
DE: 5104 Fracture and flow
DE: 7280 Volcano seismology (8419)
DE: 8488 Volcanic hazards and risks
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2007 Fall Meeting