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Prattes, G.
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Prattes, G.
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- PublicationOpen AccessThe 6 April 2009 earthquake at L’Aquila: a preliminary analysis of magnetic field measurements(2010-02-09)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ;Villante, U.; Dipartimento di Fisica, Universit`a L’Aquila, L’Aquila, Italy ;De Lauretis, M.; Dipartimento di Fisica, Universit`a L’Aquila, L’Aquila, Italy ;De Paulis, C.; Dipartimento di Fisica, Universit`a L’Aquila, L’Aquila, Italy ;Francia, P.; Dipartimento di Fisica, Universit`a L’Aquila, L’Aquila, Italy ;Piancatelli, A.; Dipartimento di Fisica, Universit`a L’Aquila, L’Aquila, Italy ;Piancatelli, A.; Dipartimento di Fisica, Universit`a L’Aquila, L’Aquila, Italy ;Pietropaolo, E.; Dipartimento di Fisica, Universit`a L’Aquila, L’Aquila, Italy ;Vellante, M.; Dipartimento di Fisica, Universit`a L’Aquila, L’Aquila, Italy ;Meloni, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Palangio, P.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Schwingenschuh, K.; Institut f¨ur Weltraumforschung, Graz, Austria ;Prattes, G.; Institut f¨ur Weltraumforschung, Graz, Austria ;Magnes, W.; Institut f¨ur Weltraumforschung, Graz, Austria ;Nenovski, P.; Geophysical Institute, Sofia, Bulgaria; ; ; ; ; ; ; ; ; ; ; ; ;Several investigations reported the possible identification of anomalous geomagnetic field signals prior to earthquake occurrence. In the ULF frequency range, candidates for precursory signatures have been proposed in the increase in the noise background and polarization parameter (i.e. the ratio between the amplitude/power of the vertical component and that one of the horizontal component), in the changing characteristics of the slope of the power spectrum and fractal dimension, in the possible occurrence of short duration pulses. We conducted, with conventional techniques of data processing, a preliminary analysis of the magnetic field observations performed at L’Aquila during three months preceding the 6 April 2009 earthquake, focusing attention on the possible occurrence of features similar to those identified in previous events. Within the limits of this analysis, we do not find compelling evidence for any of the features which have been proposed as earthquake precursors: indeed, most of aspects of our observations (which, in some cases, appear consistent with previous findings) might be interpreted in terms of the general magnetospheric conditions and/or of different sources.600 9736 - PublicationOpen AccessUltra Low Frequency (ULF) European multi station magnetic field analysis before and during the 2009 earthquake at L'Aquila regarding regional geotechnical information(2011)
; ; ; ; ; ; ; ; ; ; ;Prattes, G. ;Schwingenschuh, K. ;Eichelberger, H. U. ;Magnes, W. ;Boudjada, M. ;Stachel, M. ;Vellante, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Villante, U.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Wesztergom, V. ;Nenovski, P. ; ; ; ; ; ;; ; ;This work presents ground based Ultra Low Fre- quency (ULF) magnetic field measurements in the frequency range from 10–15mHz from 1 January 2008 to 14 April 2009. In this time period a strong earthquake series hit the Italian Abruzzo region around L’Aquila with the main stroke of magnitude M = 6.3 on 6 April 2009. In the frame of the South European Geomagnetic Array (SEGMA), a European collaboration runs ULF fluxgate instruments providing con- tinuously magnetic field data recorded in mid- and south Eu- rope. The main scientific objective is the investigation of signal variations due to seismic activity and the discrimi- nation between other natural and human influences. The SEGMA station closest to the L’Aquila earthquake epicen- ter is L’Aquila observatory located in the epicenter region. For the scientific analysis we extract the nighttime period from 22:00–02:00 UT and determine the power spectral den- sity (PSD) of the horizontal (H) and vertical (Z) magnetic field components and the standardized polarization ratio (Z) over (H). To discriminate local emissions from global ge- omagnetic effects, data from three SEGMA stations in dis- tances up to 630 km from the epicenter region are analyzed and further compared to the independent global geomagnetic Kp index. Apart from indirect ionospheric effects, elec- tromagnetic noise could be originated in the lithosphere due to tectonic mechanisms in the earthquake focus. To estimate the amplitude of assumed lithospheric electromagnetic noise emissions causing anomalies in the PSD of the (Z) compo- nent, we consider magnetotelluric calculations of the electric crust conductivity in the L’Aquila region. Results found at L’Aquila observatory are interpreted with respect to the litho- sphere electrical conductivity in the local observatory region, the Kp index, and further in a multi station analysis. Pos- sible seismic related ULF anomalies occur ∼2 weeks before the main stroke.208 180