Discrimination between pre-seismic electromagnetic anomalies and solar activity effects

Koulouras, Grigorios; Balasis, Georgios; Kiourktsidis, Ilias; Nannos, E; Kontakos, Kyriakos; Stonham, John; Ruzhin, Y; Eftaxias, K.; Cavouras, D.; Nomicos, C.

doi:10.1088/0031-8949/79/04/045901

Cited by 8 publications

(9 citation statements)

References 42 publications

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“…Notice, following the procedure which has been reported in Ref. [24], we have rather excluded the possibility that these anomalies were related to magnetic storm activity, solar flare activity or man-made electromagnetic sources. It is an open question if these, strange for us, anomalies were seismogenic ones or they were rooted in an unknown source.…”

Section: Conclusion and Discussionmentioning

confidence: 99%

Critical features in electromagnetic anomalies detected prior to the L’Aquila earthquake

Contoyiannis

Nomicos

Kopanas

et al. 2010

Physica A: Statistical Mechanics and its Applications

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a b s t r a c tEarthquakes (EQs) are large-scale fracture phenomena in the Earth's heterogeneous crust. Fracture-induced physical fields allow a real-time monitoring of damage evolution in materials during mechanical loading. Electromagnetic (EM) emissions in a wide frequency spectrum ranging from kHz to MHz are produced by opening cracks, this can be considered as the so-called precursors of general fracture. We emphasize that the MHz radiation appears earlier than the kHz on both laboratory and geophysical scales. An important challenge in this field of research is to distinguish characteristic epochs in the evolution of precursory EM activity and identify them with the equivalent last stages in the EQ preparation process. Recently, we proposed the following two-stage model. (i) The first epoch, which includes the initial emergent MHz EM emission, is thought to be due to the fracture of a highly heterogeneous system that surrounds a family of large high-strength asperities distributed along the activated fault sustaining the system. (ii) The second epoch, which includes the emergent strong impulsive kHz EM radiation, is due to the fracture of the asperities themselves. A catastrophic EQ of magnitude Mw = 6.3 occurred on 6 April, 2009 (06/04/09) in central Italy. The majority of the damage occurred in the city of L'Aquila. Clear kHz-MHz EM anomalies had been detected prior to the L'Aquila EQ. Here, we investigate the seismogenic origin of the MHz part of the anomalies. The analysis, which is in terms of intermittent dynamics of critical fluctuations, reveals that the candidate EM precursor (i) can be described as analogous to a thermal continuous phase transition and (ii) has anti-persistent behavior. These features suggest that this candidate precursor was triggered by microfractures in the highly disordered system that surrounded the backbone of asperities of the activated fault. A criterion for underlying strong critical behavior is introduced. In this field of research, reproducibility of results is desirable; and is best done by analyzing a number of precursory MHz EM emissions. We refer to previous studies of precursory MHz EM activities associated with nine significant EQs that have occurred in Greece in recent years. We conclude that all the MHz EM precursors studied, including the present one, can be described as analogous to a continuous second-order phase transition having strong criticality and anti-persistent behavior.

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Section: Conclusion and Discussionmentioning

confidence: 99%

Critical features in electromagnetic anomalies detected prior to the L’Aquila earthquake

Contoyiannis

Nomicos

Kopanas

et al. 2010

Physica A: Statistical Mechanics and its Applications

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“…According to Koulouras et al [30], laboratory studies show that electromagnetic emissions in a wide frequency spectrum ranging from kilohertz (kHz) to megahertz (MHz) frequencies are produced by the opening of microcracks, with the MHz radiation appearing earlier than the kHz radiation. Since earthquakes are large-scale fracture phenomena in the Earth's heterogeneous crust, the radiated kHz-MHz electromagnetic emissions are detectable at a geological scale.…”

Section: ×10mentioning

confidence: 99%

“…Since earthquakes are large-scale fracture phenomena in the Earth's heterogeneous crust, the radiated kHz-MHz electromagnetic emissions are detectable at a geological scale. A technique that uses the earth's electromagnetic emissions to predict earthquakes before its occurrence by a few days to a few hours before destructive earthquakes in Greece is discussed in Koulouras et al [30].…”

Section: ×10mentioning

confidence: 99%

On the Design of High-Rise Buildings for Multihazard: Fundamental Differences between Wind and Earthquake Demand

Aly

Abburu

2015

Shock and Vibration

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In the past few decades, high-rise buildings have received a renewed interest in many city business locations, where land is scarce, as per their economics, sustainability, and other benefits. Taller and taller towers are being built everywhere in the world. However, the increased frequency of multihazard disasters makes it challenging to balance between a resilient and sustainable construction. Accordingly, it is essential to understand the behavior of such structures under multihazard loadings, in order to apply such knowledge to design. The results obtained from the dynamic analysis of two different high-rise buildings (54-story and 76-story buildings) investigated in the current study indicate that earthquake loads excite higher modes that produce lower interstory drift, compared to wind loads, but higher accelerations that occur for a shorter time. Wind-induced accelerations may have comfort and serviceability concerns, while excessive interstory drifts can cause security issues. The results also show that high-rise and slender buildings designed for wind may be safe under moderate earthquake loads, regarding the main force resisting system. Nevertheless, nonstructural components may present a significant percentage of loss exposure of buildings to earthquakes due to higher floor acceleration. Consequently, appropriate damping/control techniques for tall buildings are recommended for mitigation under multihazard.

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“…We emphasize that: (i) following the procedure, which has been reported in (Koulouras et al, 2009), we have excluded the possibility that these anomalies were related to magnetic storm activity or solar flare activity; (ii) the emergence of these MHz anomalies were not accompanied by the appearance of kHz and ULF EM anomalies.…”

Section: Is the Evolution Towards Global Failure Irreversible After Tmentioning

confidence: 99%

Unfolding the procedure of characterizing recorded ultra low frequency, kHZ and MHz electromagnetic anomalies prior to the L'Aquila earthquake as pre-seismic ones - Part 2

Eftaxias¹,

Athanasopoulou²,

Balasis³

et al. 2010

Nat. Hazards Earth Syst. Sci.

147

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Abstract. Ultra low frequency-ULF (1 Hz or lower), kHz and MHz electromagnetic (EM) anomalies were recorded prior to the L'Aquila catastrophic earthquake (EQ) that occurred on 6 April 2009. The detected anomalies followed this temporal scheme. The question effortlessly arises as to whether the observed anomalies before the L'Aquila EQ were seismogenic or not. The main goal of this work is to provide some insight into this issue. More precisely, the main aims of this contribution are threefold: How can we recognize an EM observation as pre-seismic one? We aim, through a multidisciplinary analysis to provide some elements of a definition. How can we link an individual EM anomaly with a distinctive stage of the EQ preparation process? The present analysis is consistent with the hypothesis that the kHz EM anomalies were associated with the fracture of asperities that were distributed along the L'Aquila fault sustaining the system, while the MHz EM anomalies could be triggered by fractures in the highly disordered system that surrounded the backbone of asperities of the activated fault. How can we identify precursory symptoms in an individual EM precursor that indicate that the occurrence of the EQ is unavoidable? We clearly state that the detection of a MHz EM precursor does not mean that the occurrence of EQ is unavoidable; the Correspondence to: K. Eftaxias (ceftax@phys.uoa.gr) abrupt emergence of kHz EM emissions indicate the fracture of asperities. The observed ULF EM anomaly supports the hypothesis of a relationship between processes produced by increasing tectonic stresses in the Earth's crust and attendant EM interactions between the crust and ionosphere. We emphasize that we attempt to specify not only whether or not a single EM anomaly is pre-seismic in itself, but mainly whether a combination of emergent ULF, MHz and kHz EM anomalies could be characterized as pre-earthquake.

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Discrimination between pre-seismic electromagnetic anomalies and solar activity effects

Cited by 8 publications

References 42 publications

Critical features in electromagnetic anomalies detected prior to the L’Aquila earthquake

Critical features in electromagnetic anomalies detected prior to the L’Aquila earthquake

On the Design of High-Rise Buildings for Multihazard: Fundamental Differences between Wind and Earthquake Demand

Unfolding the procedure of characterizing recorded ultra low frequency, kHZ and MHz electromagnetic anomalies prior to the L'Aquila earthquake as pre-seismic ones - Part 2

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