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Röder, H.
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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