Gas geochemistry and seismotectonics: a review

Toutain, Jean; Baubron, Jean-Claude

doi:10.1016/s0040-1951(98)00295-9

Cited by 421 publications

(260 citation statements)

References 119 publications

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“…Friedman and O'Neil, 1977), and would only affect the carbon not the oxygen-isotope systematics. However, methane and hydrogen gas have been suggested as possible precursors of seismic events (see the review of Toutain and Baubron, 1999). They could be generated on a very local scale from CO 2 and H 2 O fluids through reducing reactions on highly reactive mineral surfaces that just ruptured (Kita et al, 1982).…”

Section: Metamorphic Fluid Sources Infiltrated From Below In the San mentioning

confidence: 99%

Isotopic evidence for the infiltration of mantle and metamorphic CO2–H2O fluids from below in faulted rocks from the San Andreas Fault system

et al. 2011

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To characterize the origin of the fluids involved in the San Andreas Fault (SAF) system, we carried out an isotope study of exhumed faulted rocks from deformation zones, vein fillings and their hosts and the fluid inclusions associated with these materials. Samples were collected from segments along the SAF system selected to provide a depth profile from upper to lower crust. In all, 75 samples from various structures and lithologies from 13 localities were analyzed for noble gas, carbon, and oxygen isotope compositions. Fluid inclusions exhibit helium isotope ratios ( 3 He/ 4 He) of 0.1-2.5 times the ratio in air, indicating that past fluids percolating through the SAF system contained mantle helium contributions of at least 35%, similar to what has been measured in present-day ground waters associated with the fault . Calcite is the predominant vein mineral and is a common accessory mineral in deformation zones. A systematic variation of C-and O-isotope compositions of carbonates from veins, deformation zones and their hosts suggests percolation by external fluids of similar compositions and origin with the amount of fluid infiltration increasing from host rocks to vein to deformation zones. The isotopic trend observed for carbonates in veins and deformation zones follows that shown by carbonates in host limestones, marbles, and other host rocks, increasing with increasing contribution of deep metamorphic crustal volatiles. At each crustal level, the composition of the infiltrating fluids is thus buffered by deeper metamorphic sources. A negative correlation between calcite δ 13 C and fluid inclusion 3 He/ 4 He is consistent with a mantle origin for a fraction of the infiltrating CO 2 . Noble gas and stable isotope systematics show consistent evidence for the involvement of mantle-derived fluids combined with infiltration of deep metamorphic H 2 O and CO 2 in faulting, supporting the involvement of deep fluids percolating through and perhaps weakening the fault zone. There is no clear evidence for a significant contribution from meteoric water, except for overprinting related to late weathering.

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Section: Metamorphic Fluid Sources Infiltrated From Below In the San mentioning

confidence: 99%

Isotopic evidence for the infiltration of mantle and metamorphic CO2–H2O fluids from below in faulted rocks from the San Andreas Fault system

et al. 2011

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“…Additionally, it is known that atmospheric radon concentrations strongly depend on local meteorological conditions as well as precipitation and temperature in particular (Toutain et al, 1999). Fortunately, the weather conditions during the Sousel earthquake observation were consistent with "fairweather conditions", as shown in Fig.…”

Section: Discussionmentioning

confidence: 67%

“…These reported occurrences include unusual ultra-low-frequency electromagnetic emissions (ULF) (Bleier et al, 2009), anomalies in very-low (VLF) and low-frequencies (LF) radio transmissions (Biagi et al, 2009), variation of the ionosphere total electron content (TEC) (Chauhan et al, 2009), atypical emissions of infrared radiation (IR) (Ouzounov et al, 2007), and anomalous levels of various geochemical elements (radon in particular) in the earthquake preparation zone (for a review of this complex topic, see Toutain et al, 1999).…”

Section: Introductionmentioning

confidence: 99%

Atmospheric electrical field decrease during the <i>M = 4.1</i> Sousel earthquake (Portugal)

Silva

Bezzeghoud

Reis

et al. 2011

Nat. Hazards Earth Syst. Sci.

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Abstract. In this paper, we report the observation of a significant decrease of the vertical component of the atmospheric electrical field in theÉvora region (Portugal) during the M = 4.1 Sousel earthquake of 27 March 2010. The epicentre of the earthquake was 52 km from the observation site, which falls within the theoretical earthquake preparation radius. A simple interpretation based on hypothetical radon emissions is presented, and future experiments required to elucidate these observations are outlined. To our knowledge, this is the first reported observation of a decrease of the atmospheric electrical field preceding an earthquake.

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“…Regarding gases, in active tectonic environments, methane is released close to major crustal discontinuities. In particular, CH 4 bearing spring gases are often present in volcanic environments (Toutain and Baubron, 1999). It could justify why CH 4 is the most indicative hydrogeochemical gas in discriminating these types of signal patterns.…”

Section: Discussionmentioning

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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Gas geochemistry and seismotectonics: a review

Cited by 421 publications

References 119 publications

Isotopic evidence for the infiltration of mantle and metamorphic CO2–H2O fluids from below in faulted rocks from the San Andreas Fault system

Isotopic evidence for the infiltration of mantle and metamorphic CO2–H2O fluids from below in faulted rocks from the San Andreas Fault system

Atmospheric electrical field decrease during the <i>M = 4.1</i> Sousel earthquake (Portugal)

Detection of hydrogeochemical seismic precursors by a statistical learning model

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Gas geochemistry and seismotectonics: a review

Cited by 421 publications

References 119 publications

Isotopic evidence for the infiltration of mantle and metamorphic CO2–H2O fluids from below in faulted rocks from the San Andreas Fault system

Isotopic evidence for the infiltration of mantle and metamorphic CO2–H2O fluids from below in faulted rocks from the San Andreas Fault system

Atmospheric electrical field decrease during the &lt;i&gt;M = 4.1&lt;/i&gt; Sousel earthquake (Portugal)

Detection of hydrogeochemical seismic precursors by a statistical learning model

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Atmospheric electrical field decrease during the <i>M = 4.1</i> Sousel earthquake (Portugal)