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Büttner, R.
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- PublicationOpen AccessLaboratory studies on electrical effects during volcanic eruptions(1999-06)
; ; ; ;Röder, H.; Institut für Geophysik, Universität Stuttgart, Germany ;Zimanowski, B.; Institut für Geologie, Universität Würzburg, Germany ;Büttner, R.; Institut für Geologie, Universität Würzburg, Germany; ;This laboratory study reports on electrical phenomena during the explosive eruption of a basaltoid silicate melt. Contact electricity is produced in the phase of thermo-hydraulic fracturing of magma during the explosive interaction with water. The electrical charge produced is directly proportional to the force of the explosion, as the force of explosion is linearly proportional to the surface generated by the thermo-hydraulic fracturing. Simulation of the ejection history using inerted gas as a driving medium under otherwise constant conditions did not result in significant electric charging. The results have the potential to explain in nature observed lightening in eruption clouds of explosive volcanic events.172 359 - PublicationOpen AccessElectrostatic field variations related to the big Sumatra earthquake(2006-04)
; ; ; ; ; ; ;Braun, T.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Röder, H.; Physikalisch Vulkanologisches Labor, Uni-Würzburg, ;Schuhmann, W.; Physikalisch Vulkanologisches Labor, Uni-Würzburg, ;Boschi, E.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Büttner, R.; Physikalisch Vulkanologisches Labor, Uni-Würzburg, ;Zimanowski, B.; Physikalisch Vulkanologisches Labor, Uni-Würzburg,; ; ; ; ; Electrical effects in correlation with earthquakes have been reported by many authors and different theories are discussed about the origin of these seismo-electrical effects. The actually most popular models consider piezoelectric effects, electro-kinetic effects, surface charge on crack wall, and rock/magma fragmentation as probable mechanism for the generation of electromagnetic emissions. Recently also laboratory experiments have been performed to study the mechanisms of rock fracturing, frictional sliding, and stick-slip phenomena. In this context our group has developed a method for monitoring of instable mountain flanks, which is presently tested at several sites. Here we report on extraordinary electrical signals, recorded by a station in Italy, that clearly corresponds to the Mw=9.3 earthquake of December 26, 2004, which occurred at 00:58:50.7 (UTC) “off the west coast of northern Sumatra, Indonesia” at 3.50 N, 95.72 E. Electrical monitoring with this method can be an additional tool for the global detection of very strong earthquakes. As this signals travel at the speed of light, the alert window will be significantly increased.157 83 - PublicationOpen AccessGreat Sumatra Earthquake Registers on Electrostatic Sensor(2005-11-08)
; ; ; ; ; ; ;Seismological Observatory, INGV Arezzo ;Röder, H.; Physikalisch Vulkanologisches Labor Universität Würzburg, Germany ;Braun, T.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Schuhmann, W.; Physikalisch Vulkanologisches Labor Universität Würzburg, Germany ;Boschi, E.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione AC, Roma, Italia ;Büttner, R.; Physikalisch Vulkanologisches Labor Universität Würzburg, Germany ;Zimanowski, B.; Physikalisch Vulkanologisches Labor Universität Würzburg, Germany; ; ; ; ; Strong electrical signals that correspond to the Mw = 9.3 earthquake of 26 December 2004, which occurred at 0058:50.7 UTC off the west coast of northern Sumatra, Indonesia, were recorded by an electrostatic sensor (a device that detects short-term variations in Earth’s electrostatic fi eld) at a seismic station in Italy, which had been installed to study the infl uence of local earthquakes on a new landslide monitoring system. Electrical signals arrived at the station practically instantaneously and were detected up to several hours before the onset of the Sumatra earthquake (Figure 1) as well as before local quakes. The corresponding seismic signals (p-waves) arrived 740 seconds after the start of the earthquake. Because the electrical signals travel at the speed of light, electrical monitoring for the global detection of very strong earthquakes could be an important tool in signifi cantly increasing the hazard alert window.175 341 - PublicationRestrictedThe 7 September 2008 Vulcanian explosion at Stromboli volcano: Multiparametric characterization of the event and quantification of the ejecta(2012-04)
; ; ; ; ; ; ; ; ; ; ;Calvari, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Buttner, R. ;Cristaldi, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Dellino, P. ;Giudicepietro, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia ;Orazi, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia ;Peluso, R.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia ;Spampinato, L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Zimanowski, B. ;Boschi, E.; ;; ;; ; ; ; ;On 7 September 2008 a major ash explosion occurred from the SW summit crater of Stromboli volcano. This explosive event lasted ~2 min and consisted of three discrete eruptive pulses, forming an eruptive ash cloud ~500–600 m high and ~300 m wide, 11 rising with speed of 20–27 m s-1. The event was recorded by our camera and seismic networks, as well as by two electric stations installed at a 500 m mean distance from the SW crater. The electric signals recorded by the two stations during this event were 106 times greater than signals recorded during the persistent Strombolian activity, and the seismic trace had a bigger amplitude and a longer duration. Camera image analysis allowed us to infer that a partial obstruction took place at the SW crater three days before the explosive event, suggesting that a constriction within the upper conduit could have likely led to magma overpressure. Data analysis, combined with previous experimental investigations, revealed that the higher energy output of the ash explosion, when compared to the persistent Strombolian activity, resulted in a greater magma fragmentation and erupted mass. Integration of the different parameters allowed us to classify the event as a Vulcanian type, and electric signal analysis enabled retrieval of the total volume of erupted ash and of the amounts of the juvenile, phreatomagmatic, and lithic components.452 49 - PublicationRestrictedConduit flow experiments help constraining the regime of explosive eruptions(2010)
; ; ; ; ; ; ; ; ; ; ; ; ;Dellino, P. ;Dioguardi, F. ;Zimanowski, B. ;Buttner, R. ;Mele, D. ;La Volpe, L. ;Sulpizio, R. ;Doronzo, D.M. ;Sonder, I. ;Bonasia, R. ;Calvari, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Marotta, E.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia ; ; ; ; ; ; ; ; ; ;; It is currently impractical to measure what happens in a volcano during an explosive eruption, and up to now much of our knowledge depends on theoretical models. Here we show, by means of large‐scale experiments, that the regime of explosive events can be constrained on the basis of the characteristics of magma at the point of fragmentation and conduit geometry. Our model, whose results are consistent with the literature, is a simple tool for defining the conditions at conduit exit that control the most hazardous volcanic regimes. Besides the well‐known convective plume regime, which generates pyroclastic fallout, and the vertically collapsing column regime, which leads to pyroclastic flows, we introduce an additional regime of radially expanding columns, which form when the eruptive gas‐particle mixture exits from the vent at overpressure with respect to atmosphere. As a consequence of the radial expansion, a dilute collapse occurs, which favors the formation of density currents resembling natural base surges. We conclude that a quantitative knowledge of magma fragmentation, i.e., particle size, fragmentation energy, and fragmentation speed, is critical for determining the eruption regime.332 25