Some aspects of man-made contamination on ULF measurements

Villante, U.; Vellante, M.; Piancatelli, A.; Cienzo, A. Di; Zhang, T. L.; Magnes, W.; Wesztergom, Viktor; Meloni, A.

doi:10.5194/angeo-22-1335-2004

Cited by 8 publications

(8 citation statements)

References 26 publications

(15 reference statements)

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“…Figure 5a-c show the signal behaviour for the entire three days (00:00-24:00 LT) preceding the event: as can be seen, in addition to the well known daily modulation related to ionospheric and magnetospheric processes (less evident in the Pc4-Pc5 bands) as well as to man-made contamination (more explicit at higher frequencies, Villante et al, 2004), the experimental results do not reveal any increase of activity starting few hours before the earthquake (Fraser-Smith et al, 1990;Bernardi et al, 1991;Molchanov et al, 1992). Similarly, the polarization parameter (Fig.…”

Section: The Short Term Behaviormentioning

confidence: 94%

“…The rms of the quantization noise is less than 0.5 pT in the frequency range 1-500 mHz. According to Villante and Vellante (1998) and Villante et al (2004), the man-made contamination determines in the ULF bands a weekly modulation with minimum power values on Sundays and reduced power level on Saturdays; such contamination would provide an additional noise during weekdays (daytime hours) of ∼1 pT (Pc1), ∼2 pT (Pc2), ∼3 pT (Pc3), while no significant contamination was determined in the lower frequency bands and, in general, during nighttime hours.…”

Section: Introductionmentioning

confidence: 99%

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The 6 April 2009 earthquake at L'Aquila: a preliminary analysis of magnetic field measurements

Villante

Lauretis

Paulis

et al. 2010

Nat. Hazards Earth Syst. Sci.

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Abstract. 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.

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Section: The Short Term Behaviormentioning

confidence: 94%

Section: Introductionmentioning

confidence: 99%

The 6 April 2009 earthquake at L'Aquila: a preliminary analysis of magnetic field measurements

Villante

Lauretis

Paulis

et al. 2010

Nat. Hazards Earth Syst. Sci.

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“…In order to investigate the possible disappearance (or significant reduction) of the man-made contamination during short intervals in the middle of the night, Villante et al [2004] conducted the same kind of analysis for different time intervals in the nighttime sector.…”

Section: Introductionmentioning

confidence: 99%

Electromagnetic background noise at L’Aquila Geomagnetic Observatory

Santarelli

Palangio

Lauretis

2014

Annals of Geophysics

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In this paper we analyze the electromagnetic background noise at L’Aquila Geomagnetic Observatory during 2006 and 2007 in the frequency band 1-100 mHz. In this band a pronounced daily variation is observed both in the natural signals as well as in the artificial ones, giving rise to the problem of separating different contributions of very similar morphology. We analyzed periods when the local K index was approximately zero, in correspondence with minimum of the magnetospheric and ionospheric activity. We found that in our area the main source of artificial noise is constituted by the DC electrified railways.

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“…At this site, ULF measurements have routinely been conducted since 1985, and a previous analysis U. Villante et al: On the man-made contamination on ULF measurements revealed during the period 2000-2002 (104 < R s < 120) a weekly modulation of the ULF power on the vertical component (Z) with minimum values on Sundays (10-20 % smaller than during the week), and some evidence for a similar behavior in the horizontal components H (north-south) and D (east-west) (Villante et al, 2004; see also Villante and Vellante, 1998). Recently, Santarelli et al (2014) considered the daily distribution of the root mean square (rms) of components on a hourly base, selecting intervals with local index K ≈ 0 during the period 2006-2007, and found maximum amplitude around noon in the H component, in the entire morning in the D component, and two maxima at ≈ 06:00 and ≈ 15:00 UT in the Z component.…”

Section: Introductionmentioning

confidence: 99%

On the man-made contamination on ULF measurements: evidence for disturbances related to an electrified DC railway

Villante

Piancatelli

Palangio³

2014

Ann. Geophys.

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Abstract. An analysis of measurements performed at L'Aquila (Italy) during a deep minimum of solar and magnetospheric activity (2008)(2009)(2010) allowed for the evaluation of possible contamination of the ultralow-frequency (ULF) spectrum (f ≈ 1-500 mHz) from artificial disturbances, practically in absence of natural signals. In addition, the city evacuation and the interruption of all industrial and social activities after the strong earthquake of 6 April 2009 allowed also for the examination of possible changes of the contamination level under remarkably changed environmental conditions. Our analysis reveals a persistent, seasonindependent, artificial signal, with the same characteristics in the H and Z components, that affects during daytime hours the entire spectrum; such contamination persists after the city evacuation. We speculate that the DC electrified railway (located ≈ 33 km from the Geomagnetic Observatory of L'Aquila, it maintained the same train traffic after the earthquake) is responsible for the observed disturbances.

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Some aspects of man-made contamination on ULF measurements

Cited by 8 publications

References 26 publications

The 6 April 2009 earthquake at L'Aquila: a preliminary analysis of magnetic field measurements

The 6 April 2009 earthquake at L'Aquila: a preliminary analysis of magnetic field measurements

Electromagnetic background noise at L’Aquila Geomagnetic Observatory

On the man-made contamination on ULF measurements: evidence for disturbances related to an electrified DC railway

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