Anomalous Changes in Groundwater Chemistry. Possible Precursors of the 1995 Hyogo-ken Nanbu Earthquake, Japan.

Tsunogai, Urumu; Wakita, Hiroshi

doi:10.4294/jpe1952.44.381

Cited by 41 publications

(22 citation statements)

References 10 publications

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“…Mechanisms responsible for hydrochemical signals likely include changes in aquifer permeability or the mixing ratios of genetically different waters (Tsunogai and Wakita 1996;Bolognesi 1997). Similar processes can cause hydrological signals such as water level changes (Roeloffs, 1988;Montgomery and Manga, 2003).…”

Section: Background -Earthquake Related Signalsmentioning

confidence: 99%

Hydrogeological and Gasgeochemical Earthquake Precursors ? A Review for Application

2005

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Even if earthquake precursory signals can be identified, how can they be useful? This paper investigates relationships among the attributes of 229 proposed earthquake related gasgeochemical and hydrogeological precursory signals, and applies these results to improve future earthquake prediction strategies. Sub-groups of these reported signals and relationships between sub-groups are established using parameters, including earthquake magnitude, signal duration, precursory time, and epicentral distance to the monitoring site (original studies are used wherever possible to improve data quality). A strong correlation (r ¼ 0.86) between signal duration and precursory time was identified. This suggests a relationship between the investigated precursory signals and tectonic processes related to the referenced earthquakes. Moreover, these signals are categorized into four groups, reflecting differences in monitoring station densities, measurement methods and physical processes related to signal occurrence: (a) radon exhalation from the earth's crust, (b) exhalation of other gases (helium, argon and others), (c) temporal variation in water level or discharge of springs and (d) temporal variation in temperature and dissolved ions in the water of the monitoring sites. In addition, boundary functions are used to separate signal group subsets. Finally, it is shown how these boundary functions can be used in the context of an earthquake prediction strategy by identifying potential minimum magnitudes and maximum epicentral distances from the monitoring site.

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Section: Background -Earthquake Related Signalsmentioning

confidence: 99%

Hydrogeological and Gasgeochemical Earthquake Precursors ? A Review for Application

2005

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“…The former necessitates cracking water barriers, i.e., fault gauge zones or aquicludes and, subsequently, inducing the mixing of initially isolated aquifers. Chemical changes induced by such a mechanism, however, would require large-scale mixing processes (TSUNOGAI and WAKITA, 1996) and would not be compatible with short-term reversible anomalies, such as those observed in the Kuantzeling hot and artesian springs, where the chloride and sulfate contents returned to pre-seismic levels within a few days after the onset of the anomaly. The latter mechanism, on the other hand, is induced by elastic compression on aquifers, which generates pressure variations among them, enough to generate reversible changes in hydraulic levels (MUIR-WOOD and KING, 1993) and, therefore, lead to subsequent limited geochemical discharge effects (THOMAS, 1988).…”

Section: Mechanism For the Chemical Changesmentioning

confidence: 99%

Hydrogeochemical Anomalies in the Springs of the Chiayi Area in West-central Taiwan as Possible Precursors to Earthquakes

Song

Chen

et al. 2006

Pure appl. geophys.

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Water samples from both hot and artesian springs in Kuantzeling in west-central Taiwan have been collected on a regular basis from July 15, 1999 to the end of August 2001 to measure cation and anion concentrations as a tool to detect major earthquake precursors. The data identify chloride and sulfate ion anomalies few days prior to major quakes and lasting a few days afterward. These anomalies are characterized by increases in Cl ) concentrations from 34.9% to 41.2% and 71.5% to 138.1% as well as increases in SO 4 2) concentrations from 232.7% to 276.8% and 100.0% to 155.1% above the means in both hot and artesian springs. The occurrence of these anomalies is probably explained first as stress/straininduced pressure changes in the subsurface water systems which then generate precursory limited geochemical discharges at the levels of subsurface reservoirs. Therefore, finally leading to the mixing of previously separated subsurface water bodies occurs. This suggests that the hot and artesian springs in the Kuantzeling area are possible ideal sites for recording strain changes serving well as earthquake precursors.

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“…This is partly due to difficulties in the systematic investigation necessary for the statistical estimation of each precursory phenomenon in order that this formula be applied, although there have been a large number of reports of multiple precursory phenomena for individual earthquakes (e.g. Tsunogai and Wakita, 1996;Yamada andOike, 1996, Hayakawa et al, 1996;Katao et al, 1997). However, if we define precursors in a general sense as those providing information on earthquake occurrences, we can discover additional precursory parameters that could be useful for estimating earthquake probabilities.…”

Section: Introductionmentioning

confidence: 99%

Earthquake probability based on multidisciplinary observations with correlations

Imoto

2006

Earth Planet Sp

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A number of researchers have formulated earthquake probabilities based on precursory anomalies of multidisciplinary observations in which the underlying assumption is that the occurrence of one precursory anomaly is independent from those of other kinds of anomalies. Observations were classified into two groups, those events followed by an earthquake and those that were not, and the ratio of observed precursors in both groups was taken into consideration. In the present report, recent advances in statistical seismology are considered within the framework of these earthquake probabilities, and the formulations are extended to cases in which precursory anomalies are observed as continuous measurements. The effects originating from mutual correlations between two precursory anomalies are also considered. It is assumed that observed values of each discipline follow a normal distribution, either as a group of observations followed by an earthquake (conditional density distribution) or as a group of observations not followed by an earthquake (background density distribution). Special attention is given to the case in which two kinds of observations are correlated in the conditional density distribution but not in the background density distribution. The results obtained are compared with cases in which the observations are independent of each other in both distributions. The geometrical mean of the probability gain is greater in the correlated case than in the independent case and becomes infinitely large when the absolute value of the correlation coefficient approaches one. This finding enables a wider application of earthquake probability than has been previously possible based on multidisciplinary observations.

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Anomalous Changes in Groundwater Chemistry. Possible Precursors of the 1995 Hyogo-ken Nanbu Earthquake, Japan.

Cited by 41 publications

References 10 publications

Hydrogeological and Gasgeochemical Earthquake Precursors ? A Review for Application

Hydrogeological and Gasgeochemical Earthquake Precursors ? A Review for Application

Hydrogeochemical Anomalies in the Springs of the Chiayi Area in West-central Taiwan as Possible Precursors to Earthquakes

Earthquake probability based on multidisciplinary observations with correlations

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