ULF geomagnetic field measurements in Japan and some recent results associated with Iwateken Nairiku Hokubu earthquake in 1998

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Part of Special Issue "Precursory phenomena, seismic hazard evaluation and seismo-tectonic electromagnetic effects" Abstract. Results of the ULF electromagnetic emission during the Izu, 2000 earthquake (EQ) swarm and Miyake volcano eruptions during the summer period of 2000 are presented and analyzed. The analysis of the obtained data has been performed in 3 main directions: traditional statistical analysis, i.e. analysis of time dynamics of spectral density, polarization ratios and their derivatives, Principal Component Analysis, and Fractal Analysis. The statistical characteristics were studied at different frequency sub-bands in a frequency range 10 −3 -0.3 Hz. These methods of data processing are described and the obtained results are illustrated and discussed. Some peculiarities of the obtained results such as the rise of the second principal component and the rise of the fractal index can be interpreted as possible shorttime precursors.

Section: Traditional Analysismentioning

confidence: 99%

Investigation of ULF magnetic anomaly during Izu earthquake swarm and Miyakejima volcano eruption at summer 2000, Japan

Kotsarenko

Molchanov

Hayakawa

et al. 2005

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“…Recognition of anomalous pre-earthquake phenomena has been reported for major earthquakes since 1990 (Fraser-Smith et al, 1990;Bernardi et al, 1991;Molchanov et al, 1992;Kopytenko et al, 1993;Lin and Zeng, 1992;Hayakawa et al, , 1999Hayakawa et al, , 2000Kawate et al, 1998;Gotoh et al, 2002;Hattori et al, 2002Hattori et al, , 2004aHattori, 2004;Liu et al, 2006;Molchanov and Hayakawa, 2008;Chen et al, , 2011Han et al, 2011;Wen et al, 2012). These reports indicate that geomagnetic anomalies prior to earthquakes are caused by either momentary existence of earthquake-related high conductivity materials or the movement of electric current along faults (Zeng et al, 1995;Merzer and Klemperer, 1997;Yen et al, 2004).…”

Section: Introductionmentioning

confidence: 96%

Evaluation of seismo-electric anomalies using magnetic data in Taiwan

Chen

Hsu

Wen

et al. 2013

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The Parkinson vectors derived from 3-component geomagnetic data via the magnetic transfer function are discussed with respect to epicentre locations and hypocentre depths of 16 earthquakes (M ≥ 5.5) in Taiwan during a period of 2002–2005. To find out whether electric conductivity changes would happen particularly in the seismoactive depth ranges, i.e. in the vicinity of the earthquake foci, the frequency dependent penetration depth of the electromagnetic waves (skin effect) is taken into account. The background distributions involving the general conductivity structure and the coast effect at 20 particular depths are constructed using the Parkinson vectors during the entire study period. The background distributions are subtracted from the time-varying monitor distributions, which are computed using the Parkinson vectors within the 15-day moving window, to remove responses of the coast effect and underlying conductivity structure. Anomalous depth sections are identified by deviating distributions and agree with the hypocentre depths of 15 thrust and/or strike-slip earthquakes with only one exception of a normal fault event

“…Furthermore, such data could be used in the following objectives: (1) perform the correlation between the ULF and VLF/LF radio signals, for different seismic events, with the atmospheric electrical field and the radon levels; (2) theoretical modelling of the observed phenomena; (3) extend the empirical magnitude versus distance diagram for the detection of abnormal ULF signals preceding HME presented by Hattori et al (2004) to LME (working below the present detection threshold). In fact, since LME were not considered in the former diagram, the extension of such diagram could provide valuable information about the ULF precursory emissions.…”

Section: Discussionmentioning

confidence: 99%

Seismo-electromagnetic phenomena in the western part of the Eurasia-Nubia plate boundary

Silva

Bezzeghoud

Rocha

et al. 2011

Abstract. This paper presents a work that aims to monitor seismo-electromagnetic phenomena in the Western Part of the Eurasia-Nubia Plate Boundary. This region has a significant tectonic activity combined with relatively low electromagnetic noise levels, rendering high quality seismoelectromagnetic measurements possible. An overview of the seismicity of this region is presented and the research plan is discussed accordingly.