Retrospective investigation of geomagnetic field time-series during the 2009 L'Aquila seismic sequence

Nonlin. Processes Geophys.

Thomas

2013

Abstract. Ida et al. (2012) identified anomalous decreases in the fractal dimension of the vertical (Z) component of the geomagnetic field, which they interpreted as precursors to the China earthquake of 1 September 2003. According to Ida et al. (2012), short-term earthquake prediction seems to be possible only by using electromagnetic phenomena. Here, it is shown that the decreases of the fractal dimension documented by Ida et al. (2012) are not really anomalous, but they are part of the normal geomagnetic activity driven by solar–terrestrial interactions. As a consequence, these fractal dimension decreases are not related to the 1 September 2003 earthquake.

Section: Discussionmentioning

confidence: 91%

Section: Discussionmentioning

confidence: 92%

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Comment on "Fractal analysis of ULF electromagnetic emissions in possible association with earthquakes in China" by Ida et al. (2012)

Nonlin. Processes Geophys.

Thomas

2013

“…Because the Earth's crust is fluid saturated, Dahlgren et al (2014) conclude that significant electric currents are not expected to be generated the days before earthquakes during the slow stress accumulation in the region of earthquake nucleation; as a consequence no electric and magnetic signals are expected to be observed on the Earth's surface. Note that studies of data records from the L'Aquila area (see Biagi et al, 2010;Masci, 2012b;Masci and Di Persio, 2012;Masci and De Luca, 2013;Villante et al, 2010) have identified no anomalous magnetic or electric effects during the days or hours before and after the 6 April earthquake that might be hypothesized to have seismogenic origin. Still, in a recent report, Masci and Thomas (2016), by investigating magnetic field measurements from multiple magnetometers and seismic and strong motion records close to the earthquake epicentre, have shown that there is no evidence that might support the generation of an underground electric current in correspondence of the 6 April main shock, when the rupture occurred and the vast majority of mechanical energy was released.…”

Section: On the Hypothesized Generation Mechanismsmentioning

confidence: 99%

On a reported effect in ionospheric TEC around the time of the 6 April 2009 L'Aquila earthquake

Nat. Hazards Earth Syst. Sci.

Thomas

Secan

2017

Self Cite

Abstract. In a report published in Advances in Space Research, Nenovski et al. (2015) analyse ionospheric TEC (total electron content) data from GPS measurements around the time of the 6 April 2009 M w 6.1 L'Aquila (Italy) earthquake. According to the authors, TEC difference (DTEC) calculated from two GPS (Global Positioning System) receivers in central Italy shows a hump-like shape (an increase followed by a decrease) during the hours just before and shortly after the main shock. They maintain that the hump-like shape is anomalous and may be related to the earthquake. We show that the DTEC increase in the hours before the shock, as well as its subsequent slow decrease, does not have any characteristic that might support a possible relationship with the earthquake. We have also conducted our own independent analysis using the same GPS data analysed by Nenovski et al. (2015). We have found a diurnal variation in DTEC time series that shows hump-like shapes like that reported by Nenovski et al. (2015) throughout the investigated period. This demonstrates that the hump-like shape in DTEC close to the time of the 6 April earthquake is not anomalous and cannot be considered a possible earthquake-related effect.

“…The study by Masci (2010) demonstrates that the changes of the monofractal characteristics of the geomagnetic field components, which previous reports have claimed to be related to seismogenic signals, were normal disturbances induced by the variation of the global geomagnetic activity level. More recently, Masci and Di Persio (2012) investigate the possible occurrence of seismogenic signals in the magnetic field data from Published by Copernicus Publications on behalf of the European Geosciences Union. 188 F. Masci: On the multi-fractal characteristics of the ULF geomagnetic field the Geomagnetic Observatory of L'Aquila which is located only 6 km from the epicentre of the M w = 6.3 6 April 2009 L'Aquila earthquake.…”

Section: Introductionmentioning

confidence: 99%

On the multi-fractal characteristics of the ULF geomagnetic field before the 1993 Guam earthquake

Nat. Hazards Earth Syst. Sci.

2013

Abstract. Ida et al. (2005) document significant changes in the multi-fractal parameters of the ULF geomagnetic field H component starting about one month before the 1993 Guam earthquake. According to the authors, these multi-fractal signatures can be considered as precursory signals of the Guam earthquake. As a consequence, they conclude that the multifractal analysis may have an important role in the development of short-term earthquake prediction capabilities. Since this and other similar reports have motivated the idea that earthquake prediction based on electromagnetic precursory signals may one day become a routine technique, the presumed precursors need to be validated through independent datasets. In this review the seismogenic origin of the multifractal magnetic signatures documented by Ida et al. (2005) before the 8 August 1993 Guam earthquake is seriously put into question. By means of the geomagnetic K p index, it is demonstrated that these multi-fractal parameter changes are normal signals induced by the variation of the global geomagnetic activity level.