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Nenovski, P. I.
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Nenovski, P. I.
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- PublicationOpen AccessULF fluctuations of the geomagnetic field and ionospheric sounding measurements at low latitudes during the first CAWSES campaign(2006)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ;Villante, U.; Consorzio Area di Ricerca in Astrogeofisica, L’Aquila, Italy ;Vellante, M.; Consorzio Area di Ricerca in Astrogeofisica, L’Aquila, Italy ;Francia, P.; Consorzio Area di Ricerca in Astrogeofisica, L’Aquila, Italy ;Lauretis, M.; Consorzio Area di Ricerca in Astrogeofisica, L’Aquila, Italy ;Meloni, A.; Consorzio Area di Ricerca in Astrogeofisica, L’Aquila, Italy ;Palangio, P.; Consorzio Area di Ricerca in Astrogeofisica, L’Aquila, Italy ;Zolesi, B.; Consorzio Area di Ricerca in Astrogeofisica, L’Aquila, Italy ;Pezzopane, M.; Consorzio Area di Ricerca in Astrogeofisica, L’Aquila, Italy ;F¨orster, M.; GeoForschungsZentrum, Potsdam, Germany ;Zhang, T.; Space Research Institute, Austrian Academy of Sciences, Graz, Austria ;Magnes, W.; Space Research Institute, Austrian Academy of Sciences, Graz, Austria ;Nenovski, P.; Geophysical Institute, Bulgarian Academy of Science, Sofia, Bulgaria ;Cholakov, I.; Geophysical Institute, Bulgarian Academy of Science, Sofia, Bulgaria ;Wesztergom, V.; Geodetic and Geophysical Research Institute of the Hungarian Academy of Science, Sopron, Hungary; ; ; ; ; ; ; ; ; ; ; ;; We present an analysis of ULF geomagnetic field fluctuations at low latitudes during the first CAWSES campaign (29 March–3 April 2004). During the whole campaign, mainly in the prenoon sector, a moderate Pc3-4 pulsation activity is observed, clearly related to interplanetary upstream waves. On 3 April, in correspondence to the Earth’s arrival of a coronal mass ejection, two SIs are observed whose waveforms are indicative of a contribution of the high-latitude ionospheric currents to the low-latitude ground field. During the following geomagnetic storm, low frequency (Pc5) waves are observed at discrete frequencies. Their correspondence with the same frequencies detected in the radial components of the interplanetary magnetic field and solar wind speed suggests that Alfv´enic solar wind fluctuations may act as direct drivers of magnetospheric fluctuations. A cross-phase analysis, using different pairs of stations, is also presented for identifying field line resonant frequencies and monitoring changes in plasmaspheric mass density. Lastly, an analysis of ionospheric vertical soundings, measured at the Rome ionosonde station (41.8 N, 12.5 E), and vertical TEC measurements deduced from GPS signals within an European network shows the relation between the ULF resonances in the inner magnetosphere and thermal plasma density variations during geomagnetically quiet conditions, in contrast to various storm phases at the end of the CAWSES campaign.481 174 - PublicationOpen AccessLocal changes in the total electron content immediately before the 2009 Abruzzo earthquake(2015-01-01)
; ; ; ; ; ; ;Nenovski, P. I. ;Pezzopane, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Ciraolo, L. ;Vellante, M. ;Villante, U. ;De Lauretis, M. ;; ; ; ;Ionospheric TEC (total electron content) variations derived from GPS measurements recorded at 7 GPS stations in Northern, Central and Southern Italy before and after the 2009 Abruzzo earthquake (EQ) of magnitude Mw6.3 were processed and analyzed. The analysis included interpolated and non-interpolated TEC data. Variations in the TEC of both regional and local characteristics were revealed. Several regional changes were observed in the studied period: 1 January–21 April 2009. After analyzing non-interpolated TEC data of 5 GPS stations in Central Italy (Unpg (Perugia), Untr (Terni), Aqui (Aquila), M0se (Rome) and Paca (Palma Campania, (Naples)), a local disturbance of TEC was also found. This local TEC disturbance arises preparatory to the EQ main shock occurred at 01:32 UT on 06 April 2009, maximizes its amplitude of ~0.8 TECu after the shock moment and disappears after it. The local TEC disturbance was confined at heights below 160 km, i.e. in the lower ionosphere.349 197 - PublicationOpen AccessIonospheric transients observed at mid-latitudes prior to earthquake activity in Central Italy(2010-06-17)
; ; ; ; ; ; ;Nenovski, P.; Geophysical Institute, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria ;Spassov, Ch.; Geophysical Institute, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria ;Pezzopane, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Villante, U.; Dipartimento di Fisica, Università dell’Aquila, L’Aquila, Italy ;Vellante, M.; Dipartimento di Fisica, Università dell’Aquila, L’Aquila, Italy ;Serafimova, M.; Geophysical Institute, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria ;; ; ; ; Ionograms from Rome (41.8N, 12.5E) and Sofia (42.4N, 23.2E) ionospheric stations during earthquake(EQ)activity with magnitude(M)between 5 and 6 in Central Italy are analyzed. It is found that several ionospheric disturbances occur in the intermediate E-F region before the EQ shock. In fact, besides sporadic E (Es) layer development(of type h) of short duration (transients), fmin increase, trace gaps near the critical frequencies, and E region trace disappearance are also observed within one to three hours before the EQ shock. Before the EQ shocks we find that the F2 region parameters are practically undisturbed. The only exception is the so-called fork trace that appears mostly near the critical frequency of the F2 region. Acoustic gravity waves (AGW) are suggested as one of the possible sources of transients observed in the ionosphere before the EQ shock.257 181 - 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