Sensitivity of Deep-Towed Marine Electrical Resistivity Imaging Using Two-Dimensional Inversion: A Case Study on Methane Hydrate

Chiang, Cheng-Yen; Goto, T.; Mikada, Hitoshi; Chen, Chien Chih; Hsu, Shu Kun

doi:10.3319/tao.2012.06.19.01(t)

Cited by 7 publications

(7 citation statements)

References 13 publications

(22 reference statements)

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“…However, these studies use moving electrode cables towed by a boat (e.g. Loke and Lane, 2004, Chiang et al, 2011 or Chiang et al, 2012). This approach has certain limitations: high positional uncertainty (due to failing boat navigation or wind and wave action); lower resolution and depth range (due to fewer electrodes being attached at the same time); problems relating data obtained by ERT and SONAR; and physical obstacles, such as vegetation, in the lake ( sensu Day‐Lewis et al, 2006).…”

Section: Methodsmentioning

confidence: 99%

“…Bradbury and Taylor (1984), Sambuelli et al (2011Sambuelli et al ( , 2017, or Colombero et al (2014). The efficiency of the marine resistivity measurements using this towing method was investigated by Chiang et al (2011), as well as its sensitivity using two-dimensional (2D) numerical modelling (Chiang et al, 2012). Whole measurement grid is then moved along the survey line, as described in Putiška et al (2015).…”

Section: Introductionmentioning

confidence: 99%

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Landslide‐dammed lake sediment volume calculation using waterborne ERT and SONAR profiling

Hartvich

Tábořík

Šobr

et al. 2020

Earth Surf Processes Landf

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Lake sediment volume calculation is a challenging task, namely in cases when detailed drilling is complicated, expensive, or impossible, information on the pre-sedimentation surface unavailable, and record of siltation rate non-existent or too short. This study shows how waterborne, non-invasive geophysical survey, such as electrical resistivity tomography (ERT) can be very effective in acquiring the missing data, namely when combined with sound navigation ranging (SONAR) water depth measurements and supported by information from auxiliary sources. However, ERT surveying in water environment requires specific approaches, as we illustrate on the case of the Mladotice lake study. The lake was created after a landslide in May 1872, and since its formation, the depth has gradually decreased due to sedimentation. We have reconstructed the original surface, calculated the sediment volume, and compiled information on sedimentation to estimate its remaining life span. To achieve this, we measured nine waterborne ERT profiles across the lake. To reach the necessary depth, all ERT profiles were extended on land and crossed the lake using custom-built flotation pads. ERT profiling was combined with SONAR depth measurements, historical bathymetric surveys, borehole core analysis, sediment flux measurements, volumetric calculations, and water conductivity probing. The study has achieved three main results. First, practical applicability and advantages of stationary waterborne ERT profiling in combination with bathymetric sounding were demonstrated. Second, the original lake volume and accumulated sediment was calculated. We estimate that the volume of lake sediment is 187000 m 3 , two-thirds of the original lake volume (over 275000 m 3). Finally, based on three volumetric data sets from 1972, 2003, and 2017, and recent monitoring of the sediment inflow, we propose scenarios of lake filling and its future development. Most interestingly, the sedimentation rate has decreased significantly in the last 20years, suggesting that the lake may survive much longer than hitherto expected.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Landslide‐dammed lake sediment volume calculation using waterborne ERT and SONAR profiling

Hartvich

Tábořík

Šobr

et al. 2020

Earth Surf Processes Landf

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“…Marine electromagnetic methods have gradually gained the attention of Taiwanese scientists following these MCSEM experiments (Chiang et al, 2012;Chiang et al, 2011b).…”

Section: Marine Electromagnetic Exploration Is a Geophysical Prospectmentioning

confidence: 99%

Evaluations of an ocean bottom electro-magnetometer and preliminary results offshore NE Taiwan

Lin¹,

Chiang²,

Huang³

et al. 2019

Preprint

Self Cite

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Abstract. The first stage of field experiments involving the design and construction of a low-power consumption ocean bottom electro-magnetometer (OBEM) has been completed. To improve the performance of the OBEM, we rigorously evaluated each of its units, e.g., the data loggers, acoustic parts, internal wirings, and magnetic and electric sensors, to eliminate unwanted events such as unrecovered or incomplete data. The evaluations of the procedure included the following. Data logger: digitizer sensitivity, linearity, and errors Acoustic transceiver: “ENABLE,” “DISABLE,” “RANGE,” “RELEASE1,” “RELEASE2,” and “OPTION1” functions Magnetic sensor: sensitivity of the fluxgate and orthogonality Electrical receiver: potential voltage, impedance, and frequency responses Power consumption: the maximum operating current of two sets of batteries Deployment and recovery procedures on deck We confirmed the optimal performance of the OBEM after repeatedly testing the procedures. The first offshore deployment of the OBEM together with ocean bottom seismographs (OBSs) was performed in NE Taiwan, where the water depth is approximately 1,400 m. The total intensity of the magnetic field (TMF) measured by the OBEM varied in the range of 44,100–44,150 nT, which corresponded to the proton magnetometer measurements. The daily variations of the magnetic field were recorded using the two horizontal components of the OBEM magnetic sensor. We found that the inclinations and magnetic data of the OBEM varied with two observed earthquakes when compared to the OBS data. The potential fields of the OBEM were slightly, but not obviously, affected by the earthquakes.

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“…It has higher efficiencies of spatial coverage and resolution in the shallow sub-seafloor depth than other marine EM methods. This survey system was developed first for detecting shallowly existing gas hydrate (Goto et al, 2008;Chiang et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

Internal Structure of a Seafloor Massive Sulfide Deposit by Electrical Resistivity Tomography, Okinawa Trough

Ishizu

Goto

Ohta

et al. 2019

Geophysical Research Letters

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Although seafloor massive sulfide (SMS) deposits are crucially important metal resources that contain high‐grade metals such as copper, lead, and zinc, their internal structures and generation mechanisms remain unclear. This study obtained detailed near‐seafloor images of electrical resistivity in a hydrothermal field off Okinawa, southwestern Japan, using deep‐towed marine electrical resistivity tomography. The image clarified a semi‐layered resistivity structure, interpreted as SMS deposits exposed on the seafloor, and another deep‐seated SMS layer at about 40‐m depth below the seafloor. The images reinforce our inference of a new mechanism of SMS evolution: Upwelling hydrothermal fluid is trapped under less‐permeable cap rock. The deeper embedded SMS accumulates there. Then hydrothermal fluids expelled on the seafloor form exposed SMS deposits.

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Sensitivity of Deep-Towed Marine Electrical Resistivity Imaging Using Two-Dimensional Inversion: A Case Study on Methane Hydrate

Cited by 7 publications

References 13 publications

Landslide‐dammed lake sediment volume calculation using waterborne ERT and SONAR profiling

Landslide‐dammed lake sediment volume calculation using waterborne ERT and SONAR profiling

Evaluations of an ocean bottom electro-magnetometer and preliminary results offshore NE Taiwan

Internal Structure of a Seafloor Massive Sulfide Deposit by Electrical Resistivity Tomography, Okinawa Trough

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