Radon, Cl− and SO42− anomalies in hot spring water associated with the 1995 earthquake swarm off the east coast of the Izu Peninsula, Central Japan

Nishizawa, Satoru; Igarashi, George; Sano, Yuji; Shoto, Eiji; Tasaka, S.; Sasaki, Yoshimi

doi:10.1016/s0883-2927(97)00058-9

Cited by 28 publications

(18 citation statements)

References 10 publications

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“…The changes in the water level were caused by the variations in crustal strain, a result of volumetric compression or dilatation processes before the events. Coseismic anomalies in the chemical composition of the fluid, and the flux rate or changes in water levels have been reported by various authors like Quilty & Roeloffs (1997), Nishizawa et al (1998), Favara et al (2001) and Matsumoto et al (2003). Heinicke & Koch (2000) reported several CO 2 gas flow anomalies prior to local earthquake swarms which occurred in NW‐Bohemia over a 10 yr period.…”

Section: Introductionmentioning

confidence: 80%

Gas flow anomalies in seismogenic zones in the Upper Tiber Valley, Central Italy

Heinicke¹,

Braun

Burgassi³

et al. 2006

Geophysical Journal International

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S U M M A R YCold CO 2 gas emission sites in rainwater-filled pools, so called mofettes, are widely distributed all over Italy. Their gas reservoirs, mostly having a high CO 2 content, have a magmatic and/or metamorphic origin. Temporal variations in fluid expulsions were observed at the mofettes of Caprese Michelangelo during the period from 2002 to 2005. These observations were made possible by using a new approach: photographic time-series. A first interpretation of these fluid expulsions was based on meteorological/hydrogeological explanations. However, our long-term observations show that these processes may merely be a side effect. The probable main reason for the anomalous emissions is the long-term variation in the long-distance fluid transport process from the reservoir induced by the local tectonic settings. In the northern part of the Alto Tiberina Fault, a fault intersection was reactivated by a seismic sequence which started on 2001 November 26, and continued for approximately four months. The magnitude of the main shock was M W = 4.6. As revealed by the drilling of a deep borehole, dug in the direct vicinity, overpressurized fluids trapped at a depth of 3700 m could be activated as a consequence of the improved transport conditions, that is, the fracture apertures that materialized as a result of the rupture process. A migration of the hypocentres towards the surface provides hints of a possible pore pressure diffusion process. The consequence is an increased fluid transport to the mofettes. The first indications of anomalous fluid expulsions at the mofettes of Caprese Michelangelo were detected 18 months after the seismic events.

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Section: Introductionmentioning

confidence: 80%

Gas flow anomalies in seismogenic zones in the Upper Tiber Valley, Central Italy

Heinicke¹,

Braun

Burgassi³

et al. 2006

Geophysical Journal International

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“…The sudden increase might be due to the formation of microcracks in the aquifer system and the decrease might be due to sealing of the cracks. A radon monitoring system was installed in the Yugano hot spring, Izu peninsula, Japan in May 1995 and anomalous behavior of radon was observed by Nishizawa et al (1998). They observed radon anomaly with the use of alpha-ray detector PD which is a specially designed PIN photodiode.…”

Section: Japanmentioning

confidence: 99%

Anomalous radon emission as precursor of earthquake

Ghosh

Deb

Sengupta

2009

Journal of Applied Geophysics

192

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“…Extensive earthquake prediction studies have been mainly carried out in Russia, China, and Japan as well as in other active seismic regions in the USA, India Italy, etc. On the contrary, very few earthquake prediction studies had been performed in continental areas that are classified as stable regions for seismicity in spite of the potential damage of unexpected earthquakes because of poor building Tsunogai and Wakita, 1995;Igarashi and Wakita;1995;Koizumi et al, 1996;Wakita, 1996;Sugisaki et al, 1996;Roeloffs and Quilty, 1997;Toutain et al, 1997;Nishizawa et al, 1998;Ito et al, 1999;Toutain and Baubron, 1999;Martinelli, 2000;Chia et al, 2001;Virk et al, 2001;Salazar et al, 2002;Chadha et al, 2003;Claesson et al, 2004;Song et al, 2006;Pérez and Hernández, 2007;Padrón et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

Searching and detecting earthquake geochemical precursors in CO<sub>2</sub>-rich groundwaters from Galicia, Spain

et al. 2008

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The northwestern region of the Iberian Peninsula was traditionally considered a seismically stable area. However, the 1995 and 1997 Galicia earthquakes of magnitude 4.6 and 5.3 produced significant damage in the region (intensity EMS: V), and these events changed the seismic hazard map used for the building code in Spain. Searching for earthquake precursors of these seismic events was performed, and precursory geochemical signatures of the 1995 and 1997 Galicia earthquakes were detected. These precursory signatures were observed in CO 2 -rich groundwaters from a 120 m deep well at Cabreiroá (Ourense, Galicia), ~90 km distance from the epicentres. Secular variations of the dissolved Cl -in these CO 2 -rich groundwaters showed clearly an increase trend three months before the occurrence of two earthquakes of magnitude 4.6 (November 29 and December 24, 1995) in Lugo (Galicia). After the precursory variations of Cl -prior to the earthquakes in 1995, a continuous radon monitoring system was installed at Cabreiorá's well. A significant increase of radon activity in the CO 2 -rich ground waters was detected four weeks prior to the magnitude 5.3 Galicia earthquake of May 21, 1997. Precursory changes in the chemical and isotopic composition of terrestrial fluids have been mainly attributed to the development of microcracks caused by the regional tectonic strain. The occurrence of these precursory geochemical signatures of CO 2 -rich groundwaters of magmatic origin in the NW Iberian peninsula probably suggests that high fluid pressure at depth play a major role in triggering earthquakes in the region.

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Radon, Cl− and SO42− anomalies in hot spring water associated with the 1995 earthquake swarm off the east coast of the Izu Peninsula, Central Japan

Cited by 28 publications

References 10 publications

Gas flow anomalies in seismogenic zones in the Upper Tiber Valley, Central Italy

Gas flow anomalies in seismogenic zones in the Upper Tiber Valley, Central Italy

Anomalous radon emission as precursor of earthquake

Searching and detecting earthquake geochemical precursors in CO<sub>2</sub>-rich groundwaters from Galicia, Spain

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