scholarly journals Anomalous frequency characteristics of groundwater level before major earthquakes in Taiwan

2013 ◽  
Vol 17 (5) ◽  
pp. 1693-1703 ◽  
Author(s):  
C.-H. Chen ◽  
C.-H. Wang ◽  
S. Wen ◽  
T.-K. Yeh ◽  
C.-H. Lin ◽  
...  
Keyword(s):  
Frequency Band ◽  
Groundwater Level ◽  
Barometric Pressure ◽  
Frequency Characteristics ◽  
Alluvial Fan ◽  
Water Levels ◽  
Earth Tides ◽  
Groundwater Levels ◽  
Surface Displacements ◽  
Central Taiwan

Abstract. Unusual decreases of water levels were consistently observed in 78% (= 42/54) of wells in the Choshuichi Alluvial Fan of central Taiwan about 250 days before the Chi-Chi earthquake (M = 7.6 on 20 September 1999) while possible factors of barometric pressure, earth tides, precipitation as well as artificial pumping were removed. Variations in groundwater levels measured on anomalous wells from 1 August 1997 to 19 September 1999, which covers the 250 day unusual decreases, were transferred into the frequency domain to unveil frequency characteristics associated with the Chi-Chi earthquake. Analytical results show that amplitudes at the frequency band between 0.02 day−1 and 0.04 day−1 generally maintained at the low stage and were apparently enhanced a few weeks before the Chi-Chi earthquake. Variations of amplitude at this particular frequency band were further examined along with other Taiwan earthquakes (M > 6) from 1 August 1997 to 31 December 2009. Features of the enhanced amplitudes at the frequency band are consistently observed prior to the other two earthquakes (the Rei-Li and Ming-Jian earthquakes) during the 12.5 yr study period. In addition, surface displacements recorded from GPS, which provides insights into understanding stress status in subsurface during the Chi-Chi earthquake, are also inspected. The result confirms that abnormal rise and fall changes in groundwater level yield an agreement with forward and backward surface displacements around the epicentre prior to the Chi-Chi earthquake.

scholarly journals Anomalous frequency characteristics of groundwater levels before major earthquakes in Taiwan

2012 ◽  
Vol 9 (6) ◽  
pp. 6979-7000
Author(s):  
C.-H. Chen ◽  
C.-H. Wang ◽  
S. Wen ◽  
T.-K. Yeh ◽  
C.-H. Lin ◽  
...  
Keyword(s):  
Frequency Band ◽  
Barometric Pressure ◽  
Alluvial Fan ◽  
Water Levels ◽  
Earth Tides ◽  
Strong Earthquakes ◽  
Groundwater Levels ◽  
Time Period ◽  
Central Taiwan ◽  
Geomagnetic Anomalies

Abstract. Unusual decreases in water levels were consistently observed in 78% (=42/54) of the wells in the Choshuichi Alluvial Fan of central Taiwan roughly 150 days before the Chi-Chi earthquake (M = 7.6 on 20 September 1999) when the influences of barometric pressure, earth tides, precipitation and artificial pumping were removed. Variations in groundwater levels measured in the anomalous wells between 1 August 1997 and 19 September 1999, the time period covering the unusual decreases, were transferred into the frequency domain to examine anomalous frequency bands associated with the Chi-Chi earthquake. Analytical results show that amplitudes at the frequency band between 0.02 day−1 and 0.04 day−1 were generally maintained at the low stage and were enhanced in the few weeks before the Chi-Chi earthquake. Variations in amplitude within this particular frequency band were further examined in association with earthquakes (M > 6) between 1 August 1997 and 31 December 2009. Enhanced amplitude phenomena are consistently observed prior to the other two earthquakes (the Rei-Li and Ming-Jian earthquakes) during the 12.5 yr, which sheds a promising light on research into precursors of strong earthquakes when combined with other geophysical observations such as geomagnetic anomalies and crustal displacements.

scholarly journals Frequency anomaly of groundwater level before major earthquakes in Taiwan

2015 ◽  
Vol 372 ◽  
pp. 101-104 ◽  
Author(s):  
T.-K. Yeh ◽  
C.-H. Chen ◽  
C.-H. Wang ◽  
S. Wen
Keyword(s):  
Frequency Domain ◽  
Frequency Band ◽  
Groundwater Level ◽  
Frequency Characteristics ◽  
Water Levels ◽  
The Other ◽  
Groundwater Levels ◽  
Analytical Results ◽  
Surface Displacements ◽  
Central Taiwan

Abstract. Anomalous decreases on water levels were observed in 78 % of wells in central Taiwan about 250 days before the Chi-Chi earthquake whose magnitude is 7.6 on 20 September 1999. Variations in groundwater levels measured on anomalous wells from 1 August 1997 to 19 September 1999, were transferred into the frequency domain to unveil frequency characteristics. Analytical results show that amplitudes at the frequency band between 0.02 and 0.04 day−1 generally maintained at low stage and were apparently enhanced a few weeks before the Chi-Chi earthquake. Variations of amplitude at this particular frequency band were further examined along with other Taiwan earthquakes whose magnitude is larger than 6 from 1 August 1997 to 31 December 2009. Features of the enhanced amplitudes at the frequency band are consistently observed prior to the other two earthquakes during the 12.5-year study period. Result confirms that abnormal rise and fall changes in groundwater level yield an agreement with forward and backward surface displacements around epicenter prior to the Chi-Chi earthquake.

scholarly journals Seismically induced changes in groundwater levels and temperatures following the ML5.8 (ML5.1) Gyeongju earthquake in South Korea

2021 ◽  
Author(s):  
Soo-Hyoung Lee ◽  
Jae Min Lee ◽  
Sang-Ho Moon ◽  
Kyoochul Ha ◽  
Yongcheol Kim ◽  
...  
Keyword(s):  
South Korea ◽  
Groundwater Level ◽  
Seismic Waves ◽  
Groundwater Resources ◽  
Fluid Pressure ◽  
Water Levels ◽  
Aquifer System ◽  
Groundwater Levels ◽  
Monitoring Wells ◽  
Gyeongju Earthquake

AbstractHydrogeological responses to earthquakes such as changes in groundwater level, temperature, and chemistry, have been observed for several decades. This study examines behavior associated with ML 5.8 and ML 5.1 earthquakes that occurred on 12 September 2016 near Gyeongju, a city located on the southeast coast of the Korean peninsula. The ML 5.8 event stands as the largest recorded earthquake in South Korea since the advent of modern recording systems. There was considerable damage associated with the earthquakes and many aftershocks. Records from monitoring wells located about 135 km west of the epicenter displayed various patterns of change in both water level and temperature. There were transient-type, step-like-type (up and down), and persistent-type (rise and fall) changes in water levels. The water temperature changes were of transient, shift-change, and tendency-change types. Transient changes in the groundwater level and temperature were particularly well developed in monitoring wells installed along a major boundary fault that bisected the study area. These changes were interpreted as representing an aquifer system deformed by seismic waves. The various patterns in groundwater level and temperature, therefore, suggested that seismic waves impacted the fractured units through the reactivation of fractures, joints, and microcracks, which resulted from a pulse in fluid pressure. This study points to the value of long-term monitoring efforts, which in this case were able to provide detailed information needed to manage the groundwater resources in areas potentially affected by further earthquakes.

Removal of Barometric Pressure Effects and Earth Tides from Observed Water Levels

Ground Water ◽  
2007 ◽  
Vol 45 (1) ◽  
pp. 101-105 ◽  
Author(s):  
Nathanial J. Toll ◽  
Todd C. Rasmussen
Keyword(s):  
Barometric Pressure ◽  
Water Levels ◽  
Pressure Effects ◽  
Earth Tides

scholarly journals Characterising hillslope–stream connectivity with a joint event analysis of stream and groundwater levels

2020 ◽  
Vol 24 (12) ◽  
pp. 5713-5744
Author(s):  
Daniel Beiter ◽  
Markus Weiler ◽  
Theresa Blume
Keyword(s):  
Time Series ◽  
Water Level ◽  
Groundwater Level ◽  
Stream Water ◽  
Water Levels ◽  
Joint Analysis ◽  
Strong Increase ◽  
Groundwater Levels ◽  
The Relationship ◽  
Insight Into

Abstract. Hillslope–stream connectivity controls runoff generation, during events and during baseflow conditions. However, assessing subsurface connectivity is a challenging task, as it occurs in the hidden subsurface domain where water flow can not be easily observed. We therefore investigated if the results of a joint analysis of rainfall event responses of near-stream groundwater levels and stream water levels could serve as a viable proxy for hillslope–stream connectivity. The analysis focuses on the extent of response, correlations, lag times and synchronicity. As a first step, a new data analysis scheme was developed, separating the aspects of (a) response timing and (b) extent of water level change. This provides new perspectives on the relationship between groundwater and stream responses. In a second step we investigated if this analysis can give an indication of hillslope–stream connectivity at the catchment scale. Stream water levels and groundwater levels were measured at five different hillslopes over 5 to 6 years. Using a new detection algorithm, we extracted 706 rainfall response events for subsequent analysis. Carrying out this analysis in two different geological regions (schist and marls) allowed us to test the usefulness of the proxy under different hydrological settings while also providing insight into the geologically driven differences in response behaviour. For rainfall events with low initial groundwater level, groundwater level responses often lag behind the stream with respect to the start of rise and the time of peak. This lag disappears at high antecedent groundwater levels. At low groundwater levels the relationship between groundwater and stream water level responses to rainfall are highly variable, while at high groundwater levels, above a certain threshold, this relationship tends to become more uniform. The same threshold was able to predict increased likelihood for high runoff coefficients, indicating a strong increase in connectivity once the groundwater level threshold was surpassed. The joint analysis of shallow near-stream groundwater and stream water levels provided information on the presence or absence and to a certain extent also on the degree of subsurface hillslope–stream connectivity. The underlying threshold processes were interpreted as transmissivity feedback in the marls and fill-and-spill in the schist. The value of these measurements is high; however, time series of several years and a large number of events are necessary to produce representative results. We also find that locally measured thresholds in groundwater levels can provide insight into the connectivity and event response of the corresponding headwater catchments. If the location of the well is chosen wisely, a single time series of shallow groundwater can indicate if the catchment is in a state of high or low connectivity.

scholarly journals Factors influencing surface water and groundwater interaction in alluvial fan

2020 ◽  
Author(s):  
Fanao Meng ◽  
Changlai Xiao ◽  
Xiujuan Liang ◽  
Ge Wang ◽  
Ying Sun ◽  
...  
Keyword(s):  
Surface Water ◽  
River Runoff ◽  
Groundwater Level ◽  
Alluvial Fan ◽  
Water Levels ◽  
Key Factors ◽  
Groundwater Exploitation ◽  
Factors Affecting ◽  
Surface Water And Groundwater ◽  
The Relationship

Abstract In this study, the surface water balance method was used to calculate the interaction between surface water and groundwater (SGW) in the Taoer River alluvial fan in Jilin Province, China, from 1956 to 2014. The automatic linear model was used to determine the key and non-key influencing factors, and correlation analysis was performed to evaluate their relationship with one another. River runoff and groundwater level were the key factors affecting the SGW interaction, and sand–gravel exposure in the fan was more conducive to SGW interaction. There was a positive correlation between runoff and SGW interaction, and the relationship between the groundwater and surface water levels was correlated and affected by groundwater exploitation and groundwater runoff. Groundwater exploitation and evaporation and precipitation indirectly influenced the SGW interaction by affecting the groundwater level and river runoff key factors, respectively, and were considered non-key factors.

Development and testing of a remote sensing-based model for estimating groundwater levels in aeolian desert areas of China

2011 ◽  
Vol 91 (1) ◽  
pp. 29-37 ◽  
Author(s):  
Aidi Huo ◽  
Xunhong Chen ◽  
Huike Li ◽  
Ming Hou ◽  
Xiaojing Hou
Keyword(s):  
Remote Sensing ◽  
Soil Moisture ◽  
Groundwater Level ◽  
Remote Sensing Data ◽  
Water Levels ◽  
Desert Area ◽  
Groundwater Levels ◽  
Sensing Data ◽  
Desert Areas ◽  
Regional Groundwater

Huo, A., Chen, X., Li, H., Hou, M. and Hou, X. 2011. Development and testing of a remote sensing-based model for estimating groundwater levels in aeolian desert areas of China. Can. J. Soil Sci. 91: 29–37. Regional groundwater level is an important data set for understanding the relationships between groundwater resources and regional ecological environments. The decline in water table levels leads to vegetation degradation and thus affects the ecological environment. Such a negative effect is especially apparent in the desertification areas. In this study, a remote-sensing based method was proposed to predict the distribution of the regional groundwater level in an aeolian desert area in northern China. The study used the Moderate Resolution Imaging Spectroradiometer (MODIS) remote sensing data and field investigations. Based on field investigation of groundwater level, soil moisture, and other supporting information in the aeolian desert area, as well as the soil moisture distribution derived from the MODIS images, empirical equations describing the relationship between the soil moisture and groundwater level were obtained. The groundwater levels derived using the MODIS image data were verified by groundwater levels measured from 58 wells. The results show that the correlation coefficient between the measured groundwater levels and the remote sensing-based estimated water levels was 0.868, indicating that the error is small and the predictions closely reflect the real water levels. This model can be used to predict groundwater levels in aeolian desert areas based on remote sensing data sets.

Identification of the Earth Tide’s Influences and its Main Influencing-Components on Groundwater Level in an Unconfined-Aquifer

2020 ◽  
Author(s):  
Jian Guo ◽  
Mo Xu ◽  
Haoxin Shi ◽  
Jianhong Ge
Keyword(s):  
Groundwater Level ◽  
Cross Correlation ◽  
Earth Tide ◽  
Unconfined Aquifer ◽  
Earth Tides ◽  
Groundwater Levels ◽  
Monitoring Well ◽  
The Earth ◽  
Cross Correlation Analysis ◽  
Periodic Changes

<p>It is well known that various kinds of factors are causing the fluctuation of the groundwater level. The influence of earth tide on groundwater is first observed in confined-aquifer, while in unconfined-aquifer, understanding the influence of earth tide on the micro-fluctuation of the water level is crucial for obtaining key geo-hydrological parameters of the aquifer. In this study, the groundwater level of a monitoring well in Kualiangzi Village, Zhongjiang County, Deyang, as well as the data of local earth tides and rainfall were collected. And then the identification of the earth tide’s influences and its main influencing-components on groundwater level were studied by means of spectral analysis, cross-correlation analysis and harmonic analysis. The results show that the local groundwater levels are featured periodic changes of 1-day, 1/2 day and 1/3 day, which are corresponded to the earth tide. Moreover, the amplitude of the groundwater levels are negatively correlated with the earth tide, and there is no obvious hysteresis between them. The main influencing-components of earth tide are K1 diurnal wave and S2 semidiurnal wave.</p>

scholarly journals Characterizing hillslope-stream connectivity with a joint event analysis of stream and groundwater levels

2020 ◽  
Author(s):  
Daniel Beiter ◽  
Markus Weiler ◽  
Theresa Blume
Keyword(s):  
Time Series ◽  
Water Level ◽  
Groundwater Level ◽  
Stream Water ◽  
Water Levels ◽  
Joint Analysis ◽  
Catchment Scale ◽  
Groundwater Levels ◽  
The Relationship ◽  
Insight Into

Abstract. Hillslope-stream connectivity controls runoff generation, both during events and baseflow conditions. However, assessing subsurface connectivity is a challenging task, as it occurs in the hidden subsurface domain where water flow cannot be easily observed. We therefore investigated if the results of a joint analysis of rainfall event responses of near-stream groundwater levels and stream water levels could serve as a viable proxy for hillslope-stream connectivity. The analysis focuses on the extent of response, correlations, lag times and synchronicity. A newly developed data analysis scheme of separating the aspects of (a) response timing and (b) extent of water level change provides new perspectives on the relationship between groundwater and stream responses. In a second step we investigated if this analysis can give an indication of hillslope-stream connectivity at the catchment scale. Stream- and groundwater levels were measured at five different hillslopes over 5 to 6 years. Using a new detection algorithm we extracted 706 rainfall response events for subsequent analysis. Carrying out this analysis in two different geological regions (schist and marls) allowed us to test the usefulness of the proxy under different hydrological settings while also providing insight into the geologically-driven differences in response behaviour. For rainfall events with low initial groundwater level, groundwater level responses often lag behind the stream with respect to the start of rise and the time of peak. This lag disappears at high antecedent groundwater levels. At low groundwater levels the relationship between groundwater and stream water level responses to rainfall are highly variable, while at high groundwater levels, above a certain threshold, this relationship tends to become more uniform. The same threshold was able to predict increased likelihood for high runoff coefficients, indicating a strong increase in connectivity once the groundwater level threshold was surpassed. The joint analysis of shallow near-stream groundwater and stream water levels provided information on the presence or absence and to a certain extent also on the degree of subsurface hillslope-stream connectivity. The underlying threshold processes were interpreted as transmissivity feedback in the marls and fill-and-spill in the schist. The value of these measurements is high, however, time series of several years and a large number of events are necessary to produce representative results. We also find that locally measured thresholds in groundwater levels can provide insight into catchment-scale connectivity and event response. If the location of the well is chosen wisely, a single time series of shallow groundwater can indicate if the catchment is in a state of high or low connectivity.

scholarly journals Determining Stress State of Source Media with Identified Difference between Groundwater Level during Loading and Unloading Induced by Earth Tides

Water ◽  
2021 ◽  
Vol 13 (20) ◽  
pp. 2843
Author(s):  
Huaizhong Yu ◽  
Chen Yu ◽  
Yuchuan Ma ◽  
Binbin Zhao ◽  
Chong Yue ◽  
...  
Keyword(s):  
Time Series ◽  
Stress State ◽  
Groundwater Level ◽  
Water Levels ◽  
Earth Tides ◽  
Fault Surface ◽  
Yunnan Region ◽  
Loading And Unloading ◽  
Seismic Stress ◽  
Large Earthquakes

The groundwater level might be adopted as a useful tool to explore pre-seismic stress change in the earth crust, because it circulates in the deep crust and should be altered by the processes associated with the preparation of earthquakes. This work makes a new attempt that applies the load/unload response ratio (LURR) technique to study the stress state of the source media before the large earthquakes by calculating the ratio between the water levels during the loading and unloading phases. The change of Coulomb failure stress induced by earth tides in the tectonically preferred slip direction on the fault surface of the mainshock is adopted for differentiating the loading and unloading periods. Using this approach, we tested the groundwater level in the wells near the epicenters of some large earthquakes that occurred in the Sichuan-Yunnan region of southwest China. Results show that the LURR time series fluctuated narrowly around 1.0 for many years and reached anomalously high peaks 2~8 months prior to the mainshocks. For the earthquakes with multiple observation wells, the magnitude of the maximum values decreases with the distance from the epicenter. The underlying physics of these changes should be caused by the pre-seismic dilatancy. The corresponding volume variations in the crust could be observed in the geodetic time series in the same neighborhoods and during the same period.

Sign in / Sign up

Export Citation Format

Share Document