Aquifers switched from confined to semiconfined by earthquakes

Shi, Zheming; Wang, Guangcai

doi:10.1002/2016gl070937

Cited by 60 publications

(45 citation statements)

References 39 publications

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“…The higher slope value in high‐PGA regions may result from steeply dipping and interconnected faults which act as preferential conduits for flow [ Kitagawa et al , ; Shi and Wang , ]. The general decrease of permeability with decreasing seismic activity indicates that fracturing or shearing are the dominating processes controlling permeability for all geological provinces and lithologies considered.…”

Section: Discussionmentioning

confidence: 99%

A new global database to improve predictions of permeability distribution in crystalline rocks at site scale

2017

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A comprehensive worldwide permeability data set has been compiled consisting of 29,000 in situ permeabilities from 221 publications and reports and delineating the permeability distribution in crystalline rocks into depths of 2000 meters below ground surface (mbgs). We analyze the influence of technical factors (measurement method, scale effects, preferential sampling, and hydraulic anisotropy) and geological factors (lithology, current stress regime, current seismotectonic activity, and long‐term tectonogeological history) on the permeability distribution with depth, by using regression analysis and k‐means clustering. The influence of preferential sampling and hydraulic anisotropy are negligible. A scale dependency is observed based on calculated rock test volumes equaling 0.6 orders of magnitude of permeability change per order of magnitude of rock volume tested. Based on the entire data set, permeability decreases as log(k) = −1.5 × log(z) − 16.3 with permeability k (m2) and positively increasing depth z (km), and depth is the main factor driving the permeability distribution. The permeability variance is about 2 orders of magnitude at all depths, presumably representing permeability variations around brittle fault zones. Permeability and specific yield/storage exhibit similar depth trends. While in the upper 200 mbgs fracture flow varies between confined and unconfined, we observe confined fracture and matrix flow below about 600 mbgs depth. The most important geological factors are current seismotectonic activity (determined by peak ground acceleration) and long‐term tectonogeological history (determined by geological province). The impact of lithology is less important. Based on the regression coefficients derived for all the geological key factors, permeability ranges of crystalline rocks at site scale can be predicted. First tests with independent data sets are promising.

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Section: Discussionmentioning

confidence: 99%

A new global database to improve predictions of permeability distribution in crystalline rocks at site scale

2017

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“…Earthquake‐induced horizontal permeability changes are commonly documented by analyzing the tidal response of the water level in wells on the basis of Hsieh's horizontal flow model (Elkhoury et al, ; Hsieh et al, ; Shi et al, ) or inferred from the one‐dimensional vertical groundwater diffusional model (Roeloffs, ; Rojstaczer et al, ). Vertical permeability changes are inferred from an increase in the streamflow after an earthquake using an analytical model (Wang et al, ; Wang & Manga, ) or from changes in the tidal response amplitude and phase (Shi & Wang, ; Wang et al, ). However, no studies have analyzed both the horizontal and vertical permeability variations following earthquakes.…”

Section: Introductionmentioning

confidence: 99%

Large Earthquake Reshapes the Groundwater Flow System: Insight From the Water‐Level Response to Earth Tides and Atmospheric Pressure in a Deep Well

Zhang

Shi

Wang

et al. 2019

Water Resources Research

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Quantitative evaluation of earthquake‐induced permeability changes is important for understanding key geological processes, such as advective transport of heat and solute and the generation of elevated fluid pressure. Many studies have independently documented permeability changes in either an aquifer or an aquitard, but the effects of an earthquake on both the aquifer and aquitard of the same aquifer system are still poorly understood. In this study, we use the well water‐level response to earth tides and atmospheric pressure to study the changes in hydraulic properties in an aquifer and an overlying confining layer in Beijing, China, following the 11 March 2011 Tohoku earthquake in Japan. Our results show that both the tidal response amplitude and the phase shift increased and that the phase shift changed from negative to positive after the earthquake. We identified increased permeability in both the aquifer and aquitard by the barometric response function method. The horizontal transmissivity of the aquifer increased by a factor of 6, and the vertical diffusivity of the aquitard doubled.

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“…The piezometric response to seismic waves is closely related to the transmissivity of the aquifer. In general, the higher the transmissivity, the larger the magnitude of piezometric level oscillation (Manga et al, ; Shi & Wang, ; Sun et al, ; Yan et al, ). Therefore, analyzing the characteristics of the piezometric response to earthquakes offers an effective method for understanding the hydrogeological setting of the well‐aquifer system and helps to elucidate mechanisms.…”

Section: Introductionmentioning

confidence: 99%

Changes in Permeability Caused by Two Consecutive Earthquakes—Insights From the Responses of a Well‐Aquifer System to Seismic Waves

Sun

Xiang

Shi

2019

Geophysical Research Letters

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Earthquake‐induced aquifer permeability changes have been observed both in the laboratory and the field. However, the effects of multiple earthquakes on aquifer systems have rarely been differentiated. In this study, we analyze the piezometric response to earthquake pairs that occurred on the same day. The results show that events with higher seismic energy may result in a rise in piezometric level, and the seismic waves enhanced the permeability of the aquifer by different magnitudes. Stress/strain history from consecutive earthquakes may be retained, and permeability increased much more following the second earthquake than the first one. The method proposed in this study is useful in evaluating the permeability enhancement induced by consecutive earthquakes. The stress/strain memory of aquifers also has important implications for understanding aftershocks.

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Aquifers switched from confined to semiconfined by earthquakes

Cited by 60 publications

References 39 publications

A new global database to improve predictions of permeability distribution in crystalline rocks at site scale

A new global database to improve predictions of permeability distribution in crystalline rocks at site scale

Large Earthquake Reshapes the Groundwater Flow System: Insight From the Water‐Level Response to Earth Tides and Atmospheric Pressure in a Deep Well

Changes in Permeability Caused by Two Consecutive Earthquakes—Insights From the Responses of a Well‐Aquifer System to Seismic Waves

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