Groundwater helium anomaly reflects strain change during the 2016 Kumamoto earthquake in Southwest Japan

Sano, Yuji; Takahata, Naoto; Kagoshima, Takanori; Shibata, Tomo; Onoue, Tetsuji; Zhao, Dapeng

doi:10.1038/srep37939

Cited by 75 publications

(85 citation statements)

References 26 publications

(36 reference statements)

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“…A sudden increase of the radon concentration was observed before the 1995 Kobe earthquake, which was an onshore earthquake like the 2016 Kumamoto earthquake [ Igarashi et al , ]. One study which supports this model has been published in the case of the 2016 Kumamoto earthquake [ Sano et al , ]. In this study, they collected groundwater samples before and after the 2016 Kumamoto earthquake near the epicenter and found deep groundwater helium anomaly before the main shock.…”

Section: Discussionmentioning

confidence: 72%

Preseismic ionospheric anomalies detected before the 2016 Kumamoto earthquake

Iwata

Umeno

2017

JGR Space Physics

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On 15 April 2016, the Kumamoto earthquake (Mw 7.3) occurred in Japan with no warning signals. Global Navigation Satellite System (GNSS) receivers provide useful information on disturbances in the ionosphere by calculating the changes in total electron content (TEC), which is the number of electrons in the ionosphere. Here we show our recently proposed correlation analysis of TEC data which can detect the preseismic ionospheric anomalies from the public GNSS data. Our method detected the ionospheric anomaly several tens of minutes before the 2016 Kumamoto earthquake near its epicenter. Furthermore, we gave an indicator to distinguish between the preseismic TEC anomalies and the medium‐scale traveling ionospheric disturbances (MSTIDs) by calculating the anomalous area rates. These results support the hypothesis for existence of the preceding phenomena before large earthquakes.

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Section: Discussionmentioning

confidence: 72%

Preseismic ionospheric anomalies detected before the 2016 Kumamoto earthquake

Iwata

Umeno

2017

JGR Space Physics

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“…The first profile ( Fig. 10a) is CROP M-31 (Scrocca et al, 2003a) in the version interpreted by Polonia et al (2016). The second one is CA99-215 in Fig.…”

Section: Multichannel Seismic Reflection Profilesmentioning

confidence: 98%

“…Whether these precursors truly manifest before an earthquake is a different task that has to be accomplished with specific monitoring, as we will explain in the Discussion section. Our aim is nonetheless relevant for many geoscientists as noteworthy examples of earthquake geochemical precursors are documented in many previous works Igarashi et al, 1995;Claesson et al, 2004;Huang and Ding, 2012;Inan et al, 2012;Skelton et al, 2014Skelton et al, , 2019Sano et al, 2016;Barberio et al, 2017;Petitta et al, 2018;Boschetti et al, 2019) and are very promising for the science of earthquake forecasting.…”

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confidence: 92%

The Bortoluzzi Mud Volcano (Ionian Sea, Italy) and its potential for tracking the seismic cycle of active faults

et al. 2019

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Abstract. The Ionian Sea in southern Italy is at the center of active interaction and convergence between the Eurasian and African–Adriatic plates in the Mediterranean. This area is seismically active with instrumentally and/or historically recorded Mw>7.0 earthquakes, and it is affected by recently discovered long strike-slip faults across the active Calabrian accretionary wedge. Many mud volcanoes occur on top of the wedge. A recently discovered one (called the Bortoluzzi Mud Volcano or BMV) was surveyed during the Seismofaults 2017 cruise (May 2017). High-resolution bathymetric backscatter surveys, seismic reflection profiles, geochemical and earthquake data, and a gravity core are used here to geologically, geochemically, and geophysically characterize this structure. The BMV is a circular feature ≃22 m high and ≃1100 m in diameter with steep slopes (up to a dip of 22∘). It sits atop the Calabrian accretionary wedge and a system of flower-like oblique-slip faults that are probably seismically active as demonstrated by earthquake hypocentral and focal data. Geochemistry of water samples from the seawater column on top of the BMV shows a significant contamination of the bottom waters from saline (evaporite-type) CH4-dominated crustal-derived fluids similar to the fluids collected from a mud volcano located on the Calabria mainland over the same accretionary wedge. These results attest to the occurrence of open crustal pathways for fluids through the BMV down to at least the Messinian evaporites at about −3000 m. This evidence is also substantiated by helium isotope ratios and by comparison and contrast with different geochemical data from three seawater columns located over other active faults in the Ionian Sea area. One conclusion is that the BMV may be useful for tracking the seismic cycle of active faults through geochemical monitoring. Due to the widespread diffusion of mud volcanoes in seismically active settings, this study contributes to indicating a future path for the use of mud volcanoes in the monitoring and mitigation of natural hazards.

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“…For instance, rock deformation produces new (micro) fractures enhancing the release of the trapped volatiles (e.g., He) and as a consequence the fraction of volatiles released from the rocks during deformation, increases with the rock volume changes (dilatancy processes). However, even if some experimental studies show the existence of a direct link between rock deformation/fracturation and the release of He 25,26 , there are only a few of applications in natural systems 21,27,28 . In this study, we investigated the origin and processes controlling the transfer of He through the crust in a seismically active region of the Northern Apennines ( Fig.…”

mentioning

confidence: 99%

Continental degassing of helium in an active tectonic setting (northern Italy): the role of seismicity

Buttitta

Caracausi

Chiaraluce

et al. 2020

Sci Rep

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in order to investigate the variability of helium degassing in continental regions, its release from rocks and emission into the atmosphere, here we studied the degassing of volatiles in a seismically active region of northern italy (Mw MAX = 6) at the Nirano-Regnano mud volcanic system. The emitted gases in the study area are cH 4-dominated and it is the carrier for helium (He) transfer through the crust. Carbon and He isotopes unequivocally indicate that crustal-derived fluids dominate these systems. An highresolution 3-dimensional reconstruction of the gas reservoirs feeding the observed gas emissions at the surface permits to estimate the amount of He stored in the natural reservoirs. Our study demonstrated that the in-situ production of 4 He in the crust and a long-lasting diffusion through the crust are not the main processes that rule the He degassing in the region. Furthermore, we demonstrated that microfracturation due to the field of stress that generates the local seismicity increases the release of He from the rocks and can sustain the excess of He in the natural reservoirs respect to the steady-state diffusive degassing. These results prove that (1) the transport of volatiles through the crust can be episodic as function of rock deformation and seismicity and (2) He can be used to highlight changes in the stress field and related earthquakes.

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Groundwater helium anomaly reflects strain change during the 2016 Kumamoto earthquake in Southwest Japan

Cited by 75 publications

References 26 publications

Preseismic ionospheric anomalies detected before the 2016 Kumamoto earthquake

Preseismic ionospheric anomalies detected before the 2016 Kumamoto earthquake

The Bortoluzzi Mud Volcano (Ionian Sea, Italy) and its potential for tracking the seismic cycle of active faults

Continental degassing of helium in an active tectonic setting (northern Italy): the role of seismicity

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