Groundwater level changes on Jeju Island associated with the Kumamoto and Gyeongju earthquakes

Lee, Soo-Hyoung; Cheong, Jae-Yeol; Park, Yoon-Suk; Ha, Kyoochul; Kim, Yong-Cheol; Kim, Sung-Wook; Hamm, Se‐Yeong

doi:10.1080/19475705.2017.1387181

Cited by 7 publications

(4 citation statements)

References 16 publications

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“…The following equation is used for these corrections:

X_{t}^{*} = X_{t} - \frac{X_{t - n} + \dots X_{t} + \dots X_{t + n}}{2 n + 1}

where

X_{t}^{*}

is the filtered groundwater level, X t is the raw groundwater level, and n is the time step; n = 1 was applied in this study. In previous studies, seismically induced groundwater fluctuations have been analyzed using the equation as a filtering method (Lee et al 2013, 2017).…”

Section: Resultsmentioning

confidence: 99%

Groundwater Impacts from the M5.8 Earthquake in Korea as Determined by Integrated Monitoring Systems

Lee

Yoon

et al. 2020

Groundwater

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This paper describes the impacts of the M5.8(5.1) Gyeongju earthquakes on groundwater levels using data obtained from a unique coastal monitoring well. The monitoring strategy integrates conventional water level monitoring with periodic, continuous measurements of temperature and electrical conductivity (EC) within the water column of the well. Another important component of the monitoring system is a new instrument, the InterfacEGG, which is capable of dynamically tracking the freshwater‐saltwater interface. Although the system was set up to monitor seawater intrusion related to over‐pumping, as well as rainfall and tidal effects, it recorded impacts associated with a large earthquake and aftershocks approximately 241 km away. Seismic energies associated with the M5.8(5.1) Gyeongju earthquakes induced groundwater flows to the monitoring well through fractures and joints in the crystalline basement rocks. Temperature and EC logging data showed that the EC vertical profile declined from an average of approximately 5300 to 4800 μS/cm following the earthquakes. The temperature profile showed a trend toward lower temperatures as the depth increased, a feature not commonly observed in previous studies. Data from the InterfacEGG suggested that the rise in EC was not due to the saltwater intrusion, but from the tendency for brackish water entering the borehole to induce convective mixing at deeper depths as the seismic waves travel through the well‐aquifer system. The increase in groundwater levels was caused by pulse of colder, less brackish water flowing into the well because of the earthquake. This behavior reflects an enhancement in rock permeability by removing precipitates and colloidal particles from clogged fractures, which improve the hydraulic connection with a nearby unit with a higher hydraulic head. This study suggests there is value added with a more aggressive monitoring strategy.

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“…The following equation is used for these corrections:

X_{t}^{*} = X_{t} - \frac{X_{t - n} + \dots X_{t} + \dots X_{t + n}}{2 n + 1}

where

X_{t}^{*}

Section: Resultsmentioning

confidence: 99%

Groundwater Impacts from the M5.8 Earthquake in Korea as Determined by Integrated Monitoring Systems

Lee

Yoon

et al. 2020

Groundwater

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“…where X Ã t is the filtered groundwater level, X t is the raw groundwater level, and n is the time step; n ¼ 2 was applied in this study. In previous studies, seismically induced groundwater fluctuations have been analyzed using this equation as a filtering method (Lee et al 2013;Lee et al 2017a). The filtered groundwater level, 1-hour cumulative precipitation obtained at the nearest weather station, and the time of earthquake occurrence were analyzed together and variations in their characteristics were compared.…”

Section: Modified Moving Average (Mma) Filteringmentioning

confidence: 99%

“…With the development of automatic observation systems, background groundwater levels can be derived in order to separate and analyze abnormal changes in groundwater levels due to external stresses during earthquakes (Matsumoto et al 2003a;2003b). Abnormal signal evaluation methods include the use of standard deviations (Yasuoka and Shinogi 1997), Fast-Fourier transforms (FFT; Lee et al 2009), Hilbert-Huang transformations (HHT, Huang and Wu 2008), proportional coefficients (Roeloffs 1998), and moving averages (Lee et al 2013;Lee et al 2017a).…”

Section: Introductionmentioning

confidence: 99%

Assessing aquifer responses to earthquakes using temporal variations in groundwater monitoring data in alluvial and sedimentary bedrock aquifers

Lee

Woo

Koh

et al. 2020

Geomatics, Natural Hazards and Risk

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Water level and hydrochemical parameters from groundwater monitoring wells can be effectively used for interpreting changes in the groundwater system when aquifers are appropriately characterized. Groundwater levels in six paired monitoring wells of alluvial and sedimentary bedrock aquifers in the Gyeongju area, southeastern South Korea were analyzed to evaluate their abrupt changes due to earthquakes, and to identify the differences in responses of groundwater level to the earthquakes and precipitation based on confining conditions of the aquifers, which was verified by principal component analysis (PCA) of water level and major ion concentrations, and lithologic logs. When earthquakes occurred in 2016 near the study area, the different responses of groundwater level to the earthquakes were detected in the two well pairs under confined condition. In particular, wells with single screened interval showed dissimilar patterns in water level fluctuation and hydrochemical water type. The PCA results of groundwater levels and hydrochemical parameters also substantiated the different aquifer types in the two well pairs. These results suggest that groundwater monitoring data should be acquired and analyzed considering the well design and aquifer type to properly evaluate impacts of earthquakes on the aquifers, which can contribute to establishment of earthquake monitoring systems.

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“…CC BY 4.0 License. the theoretical calculations and characterization (Gulley et al, 2013;Liu et al, 2017;Lee et al, 2017;He et al, 2020;Yan et al, 2020;Ma et al, 2023). Earth solid tides are characterized by fixed periods and amplitudes, and the tidal response of groundwater level can be conveniently utilized for quantitative calculation of well-aquifer structural parameters.…”

Section: Introductionmentioning

confidence: 99%

Analysis of phase lead "anomalies" in the tidal response of groundwater levels

He,

Liu,

Sun

et al. 2023

Preprint

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Abstract. The tidal response to the groundwater level refers to an aquifer under the influence of tidal forces, the pressure head (pore pressure) within the aquifer produces changes that drive the alternating transportation of water between well-aquifers, causing the rise and fall of the water level in the wells. Considering the driving process of force and seepage of water, the groundwater level response should only have a phase lag compared to the Earth's solid tides. However, the actual observation data show that the phase of the groundwater level tidal response exceeded that of the theoretical gravity tides, which is not in accordance with the commonly occurring mechanical process of the phenomenon. Using the theory of trans-current recharge, the seepage of aquifer water was decomposed into lateral and vertical transport, and the two kinds of "lagging" transport processes were superimposed to obtain the final groundwater level tidal response, which may appear as an anomalous phenomenon in which the phase is over the front after superposition. Taking the Lugu Lake well as an example, before the Wenchuan earthquake, the phase of groundwater level was ahead of the theoretical solid tide, indicating the existence of a transgressive aquifer, whereas the groundwater level tidal factor declined from 0.28 mm/uGal before the earthquake to 0.23 mm/uGal after the earthquake. The phase, from 15 min ahead in pre-earthquake to 15 min lagged after the earthquake, combined with the theoretical analysis it can be seen that the Wenchuan earthquake led to develop the new fissure in the Lugu Lake well, thus permanently altering its aquifer response and changing the permeability of the aquifer. However, the subsequent earthquakes did not produce new fissures; only the seismic waves caused by the stress redistribution process were observed. This co-seismic response of the groundwater level shows a step-down phenomenon, phase analysis of the groundwater level has scientific significance for the study of well-aquifer conditions and well-borehole seismic capacity.

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Groundwater level changes on Jeju Island associated with the Kumamoto and Gyeongju earthquakes

Cited by 7 publications

References 16 publications

Groundwater Impacts from the M5.8 Earthquake in Korea as Determined by Integrated Monitoring Systems

Groundwater Impacts from the M5.8 Earthquake in Korea as Determined by Integrated Monitoring Systems

Assessing aquifer responses to earthquakes using temporal variations in groundwater monitoring data in alluvial and sedimentary bedrock aquifers

Analysis of phase lead "anomalies" in the tidal response of groundwater levels

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