Preseismic ULF electromagnetic effect from observation at Kamchatka

Molchanov, O. A.; Schekotov, A.; Fedorov, E. N.; Belyaev, G.; Gordeev, E.

doi:10.5194/nhess-3-203-2003

Cited by 50 publications

(41 citation statements)

References 12 publications

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“…There are a lot of reports on wide-band SA emission before large earthquakes. For example Morgunov et al (1991) recorded a distinctive anomaly in SA noise behavior in the range F =800-1200 Hz about 16 h before the famous M=7.0 Spitak earthquake, Armenia, 1988, at the distance 80 km from the epicenter. Gorbatikov et al (2002) found an increase of the SA intensity averaged over 20 min in the frequency range from F =25 Hz to F =1000 Hz in a time 2-12 h before several moderate earthquakes (M=4-5) at the Matsushiro station in Japan.…”

Section: Introductionmentioning

confidence: 99%

Near-seismic effects in ULF fields and seismo-acoustic emission: statistics and explanation

Molchanov

Schekotov

Solovieva

et al. 2005

Nat. Hazards Earth Syst. Sci.

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Part of Special Issue "Precursory phenomena, seismic hazard evaluation and seismo-tectonic electromagnetic effects"Abstract. Preseismic intensification of fracturing has been investigated from occurrence analysis of seismo-acoustic pulses (SA foreshocks) and ULF magnetic pulses (ULF foreshocks) observed in Karimshino station in addition to seismic foreshocks. Such analysis is produced for about 40 rather strong and nearby isolated earthquakes during 2 years of recording. It is found that occurrence rate of SA foreshocks increases in the interval (−12, 0 h) before main shock with 3-times exceeding of background level in the interval (−6, −3 h), and occurrence probability of SA foreshocks (pA∼75%) is higher than probability of seismic foreshocks (ps∼30%) in the same time interval.ULF foreshocks are masked by regular ULF activity at local morning and daytime, nevertheless we have discovered an essential ULF intensity increase in the interval (−3, +1 h) at the frequency range 0.05-0.3 Hz. Estimated occurrence probability of ULF foreshocks is about 40%. After theoretical consideration we conclude: 1) Taking into account the number rate of SA foreshocks, their amplitude and frequency range, they emit due to opening of fractures with size of L=70-200 m (M=1-2); 2) The electro-kinetic effect is the most promising mechanism of ULF foreshocks, but it is efficient only if two special conditions are fulfilled: a) origin of fractures near fluid-saturated places or liquid reservoirs (aquifers); b) appearance of open porosity or initiation of percolation instability; 3) Both SA and ULF magnetic field pulses are related to near-distant fractures (r<20-30 km); 4) Taking into account number rate and activation period of seismic, SA and ULF foreshocks,it is rather probable that opening of fractures and rupture of fluid reservoirs occur in the large preparation area with horizontal size about 100-200 km.

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Section: Introductionmentioning

confidence: 99%

Near-seismic effects in ULF fields and seismo-acoustic emission: statistics and explanation

Molchanov

Schekotov

Solovieva

et al. 2005

Nat. Hazards Earth Syst. Sci.

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“…Using the former statistical information about ULF depression by Molchanov et al (2003) and Schekotov et al (2006) and also summarized in Molchanov and Hayakawa (2008), we can suppose that an EQ will happen 1-5 days after the www.ccsenet.org/esr Earth Science Research Vol. 2, No.…”

Section: Discussionmentioning

confidence: 99%

“…A different type of ULF anomaly of EQ effects has been found by Molchanov et al (2003) and Schekotov et al (2006). Being completely different from the above seismogenic lithospheric ULF emissions, this new effect is a phenomenon in the form of depression in the amplitude of ULF magnetic field fluctuations observed on the ground (probably, generated in the magnetosphere) a few days before an EQ.…”

Section: Introductionmentioning

confidence: 99%

On the Ultra-Low-Frequency Magnetic Field Depression for Three Huge Oceanic Earthquakes in Japan and in the Kurile Islands

Hayakawa¹,

Schekotov²,

Fedorov³

et al. 2012

ESR

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The depression (reduction in amplitude) of ULF (ultra-low-frequency) magnetic field variations observed on the Earth's surface is found for the recent huge Japan earthquake (EQ) (magnitude (M) ~ 9.0) on March 11, 2011 which is a typical oceanic EQ of the plate type. In order to confirm the presence of such a ULF depression, we have also studied the additional two huge oceanic EQs in the Kurile islands (M@8), and similar ULF depressions have also been detected. This suggests that such a ULF depression seems to be a universal phenomenon for huge (M=8-9) EQs even occurred in the sea bed of subduction region.

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“…2.1). The set of labels is obtained on the basis of k s index proposed by Molchanov et al (2003) and the of ε index proposed by Dobrovolsky et al (1979), shown in Fig. 1.…”

Section: Dataset Descriptionmentioning

confidence: 99%

“…Here {x t } ∞ t=1 is a real valued time series composed of daily observations of a given hydrogeochemical measurement and {y t } ∞ t=1 is time series of categorical variables with y t ∈ {−1, 0, +1}, indicating the occurrence of "no-disturbed signal", "seismic precursor", "co-post seismic precursor" respectively. This association was established both on the basis of k s index proposed by Molchanov et al (2003) and the of ε index proposed by Dobrovolsky et al (1979). These indexes take into account the relation between earthquake magnitude and distance from the epicenter to capital city Petropavlovsk.…”

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confidence: 99%

Detection of hydrogeochemical seismic precursors by a statistical learning model

Castellana

Biagi

2008

Nat. Hazards Earth Syst. Sci.

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Abstract. The problem of detecting the occurrence of an earthquake precursor is faced in the general framework of the statistical learning theory. The aim of this work is both to build models able to detect seismic precursors from time series of different geochemical signals and to provide an estimate of number of false positives. The model we used is kNearest-Neighbor classifier for discriminating "no-disturbed signal", "seismic precursor" and "co-post seismic precursor" in time series relative to thirteen different hydrogeochemical parameters collected in water samples from a natural spring in Kamchachta (Russia) peninsula. The measurements collected are ion content (Na, Cl, Ca, HCO 3 , H 3 BO 3 ), parameters (pH, Q, T) and gases (N 2 , CO 2 , CH 4 , O 2 , Ag). The classification error is measured by Leave-K-Out-CrossValidation procedure. Our study shows that the most discriminative ions for detecting seismic precursors are Cl and Na having an error rates of 15%. Moreover, the most discriminative parameters and gases are Q and CH 4 respectively, with error rate of 21%. The ions result the most informative hydrogeochemicals for detecting seismic precursors due to the peculiarities of the mechanisms involved in earthquake preparation. Finally we show that the information collected some month before the event under analysis are necessary to improve the classification accuracy.

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Preseismic ULF electromagnetic effect from observation at Kamchatka

Cited by 50 publications

References 12 publications

Near-seismic effects in ULF fields and seismo-acoustic emission: statistics and explanation

Near-seismic effects in ULF fields and seismo-acoustic emission: statistics and explanation

On the Ultra-Low-Frequency Magnetic Field Depression for Three Huge Oceanic Earthquakes in Japan and in the Kurile Islands

Detection of hydrogeochemical seismic precursors by a statistical learning model

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