Seogi Kang

• Doctor of Philosophy
• PostDoc Position at Stanford University

We present a 3D numerical modelling analysis evaluating the deployment of a borehole electromagnetic measurement tool to detect and image a stimulated zone at the Utah Frontier Observatory for Research in Geothermal Energy geothermal site. As the depth to the geothermal reservoir is several kilometres and the size of the stimulated zone is limited...

Recharge is a critical component for understanding aquifer systems and the sustainable management of groundwater resources, yet this process is challenging to measure at policy-relevant spatiotemporal scales. Building upon previous research, we tested the hypothesis that InSAR can be used to observe river-sourced recharge if the underlying recharge...

The potential for open-source software and open-science practices to accelerate research in applied geophysics and thereby contribute to solutions of geoscientific problems impacting society is considered. We provide context on the definition of open source and give a brief history of open-source software in applied geophysics. Drawing from our exp...

Plain Language Summary In the Central Valley of California, changes in ground elevation, often referred to as surface deformation, are mainly due to two hydrologic changes in the system: the changes in groundwater head, which result in a poroelastic response and the changes in mass of water, snow, and ice, which result in a hydrologic loading respo...

Given the substantial groundwater level declines in the Central Valley of California, there is an urgent need to supplement the recharge of the groundwater systems by implementing managed aquifer recharge. With approximately 170 km ³ of available groundwater storage space, water deemed to be excess during wet years could be spread on the ground sur...

Working with airborne electromagnetic (AEM) data acquired in the Kaweah Subbasin in the Central Valley of California, USA, we developed a new approach for imaging the bedrock surface and the confining Corcoran Clay layer. Our approach, which incorporated the prior knowledge of the targets for the improved imaging, included multiple L2‐norm and Lp‐n...

Geophysical electromagnetics (EM) plays an important role in mineral exploration and is increasingly being used to help solve other problems of relevance to society. In this article we reflect, from our perspective at University of British Columbia (UBC), on the development of EM geophysics over the years and on our attempts to enhance its understa...

Surface spreading recharge, the intentional flooding of the ground surface to replenish a groundwater system, is one approach used to mitigate groundwater overdraft in California's Central Valley (CV). Choosing appropriate sites for surface spreading recharge, in regard to the sites’ ability to convey water from the ground surface to the desired re...

Airborne electromagnetic (AEM) data can be inverted to recover models of the electrical resistivity of the subsurface; these, in turn, can be transformed to obtain models of sediment type. AEM data were acquired in Butte and Glenn Counties, California, USA to improve the understanding of the aquifer system. Around 800 line‐kilometers of high‐qualit...

Mapping and monitoring of saltwater intrusion are critical to the sustainable management of groundwater in coastal aquifers around the world. Increasingly, geophysical methods, such as electrical resistivity tomography (ERT), have been used to address these needs. We identified methods for the inversion of ERT data that would most accurately map th...

Geophysical electromagnetics (EM) plays an important role in mineral exploration and is increasingly being used to help solve other problems of relevance to society. In this article we reflect, from our perspective at the University of British Columbia, on the development of EM geophysics over the years, on our attempts to enhance understanding of...

The acquisition of airborne electromagnetic (AEM) data co-located with water well data provides an essential dataset for constructing an accurate rock physics relationship between resistivity from AEM and lithology from wells. Results from an AEM survey in Butte and Glenn Counties, California, U. S. A., where 41 water wells are located within 100 m...

Inversion of airborne electromagnetic data is often an iterative process, not only requiring that the researcher be able to explore the impact of changing components, such as the choice of regularisation functional or model parameterisation, but also often requiring that forward simulations be run and fields and fluxes visualised in order to build...

Electromagnetics has an important role to play in solving the next generation of geoscience problems. These problems are multidisciplinary, complex, and require collaboration. This is especially true at the base scientific level, where the underlying physical equations need to be solved, and data, associated with physical experiments, need to be in...

We provide a two-stage approach to extract spectral induced polarization (SIP) information from time-domain IP data. In the first stage we invert dc data to recover the background conductivity. In the second, we solve a linear inverse problem and invert all time channels simultaneously to recover the IP parameters. The IP decay curves are represent...

The potential for extracting and interpreting induced polarisation (IP) data from airborne surveys is now broadly recognised. There is, however, still considerable discussion about the conditions under which the technique can provide knowledge about the subsurface and thus, its practical applications. Foremost among these is whether, or under what...

The potential for extracting and interpreting induced polarization (IP) data from airborne surveys is now broadly recognized. There is, however, still considerable discussion about the conditions under which the technique can provide knowledge about the subsurface and thus, its practical applications. Foremost among these is whether, or under what...

Electromagnetics has an important role to play in solving the next generation of geoscience problems. These problems are multidisciplinary, complex, and require collaboration. This is especially true at the base scientific level where the underlying physical equations need to be solved, and data, associated with physical experiments, need to be inv...

Inversions of airborne EM data are often an iterative process, not only requiring that the researcher be able to explore the impact of changing components such as the choice of regularization functional or model parameterization, but also often requiring that forward simulations be run and fields and fluxes visualized in order to build an understan...

The presence of chargeable materials can significantly impact the data in electromagnetic (EM) surveys. This affected data has traditionally been treated as noise that must be removed prior to interpretation or inversion. The ability to extract induced polarization (IP) information from an airborne platform would be a valuable tool in the mineral e...

The Lalor deposit in Snow Lake, central Manitoba, is one of the most significant mineral discoveries in Canada in the past decade. Buried 600 m below the surface, the deposit remained undiscovered until a deep penetrating geophysical electromagnetic (EM) system was employed. Since then, the deposit has been a test site for many modern geophysical s...

Inversion of self-potential (SP) data for source current density, js, in complex volcanic settings, yields hydrological information without the need for a prior groundwater flow model. js contains information about pH, pore saturation and permeability, from which we infer the distribution of liquid and vapour phases. To understand the hydrothermal...

Electrical induced polarization (EIP) surveys are used to detect chargeable materials in the earth. For interpretation of time domain EIP data a common procedure is to first invert the DC data (electric current on-time) to recover conductivity and then invert the IP data (current off-time) to recover chargeability. This DC-IP procedure assumes that...

At some point in many geophysical workflows, an inversion is a necessary step for answering the geoscientific question at hand, whether it is recovering a reflectivity series from a seismic trace in a deconvolution problem, finding a susceptibility model from magnetic data, or recovering conductivity from an electromagnetic survey. This is particul...

The geologically distinct DO-27 and DO-18 kimberlites, often called the Tli Kwi Cho (TKC) kimberlites, have been used as a testbed for airborne geophysical methods applied to kimberlite exploration. This paper, which is the last of a three-part series, focuses on extracting chargeability information from time-domain electromagnetic (TEM) data. Thre...

We focus upon the task of finding a 3D conductivity structure for the DO-18 and DO- 27 kimberlites, historically known as the Tli Kwi Cho (TKC) kimberlite complex in the Northwest Territories, Canada. Two airborne electromagnetic (EM) surveys are analyzed: a frequency-domain DIGHEM and a time-domain VTEM survey. Airborne time-domain data at TKC are...

Simulations and inversions of geophysical electromagnetic data are paramount for discerning meaningful information about the subsurface from these data. Depending on the nature of the source electromagnetic experiments may be classified as time-domain or frequency-domain. Multiple heterogeneous and sometimes anisotropic physical properties, includi...

Simulations and inversions of electromagnetic geophysical data are paramount for discerning meaningful information about the subsurface from these data. Depending on the nature of the source electromagnetic experiments may be classified as time-domain or frequency-domain. Multiple heterogeneous and sometimes anisotropic physical properties, includi...

We develop a procedure to invert time domain induced polarization (IP) data for inductive sources. Our approach is based upon the inversion methodology in conventional electrical IP (EIP), which uses a sensitivity function that is independent of time. However, significant modifications are required for inductive source IP (ISIP) because electric fi...

SUMMARY In this study, we revisit three airborne EM surveys over Tli Kwi Cho (TKC). These consist of a frequency domain DIGHEM data set, and two time domain surveys, VTEM and AeroTEM. Negative transients have been recorded in both of the time domain surveys and we interpret these as arising from chargeable bodies. The kimberlite pipes are referred...

SUMMARY We propose a methodology to generate a 3D distribution of pseudo-chargeability from airborne time domain electromagnetic data. The processing flow is as follows: (a) Apply 3D inversion to TEM data to restore a background conductivity. This might involve omitting responses that are obviously contaminated with IP signals, such as negative tra...

Inverse modeling is a powerful tool for extracting information about the subsurface from geophysical data. Geophysical inverse problems are inherently multidisciplinary, requiring elements from the relevant physics, numerical simulation, and optimization, as well as knowledge of the geologic setting, and a comprehension of the interplay between all...

Electromagnetic (EM) methods are used to characterize the electrical conductivity distribution of the earth. EM geophysical surveys are increasingly being simulated and inverted in 3D, due in part to computational advances. However, the availability of computational resources does not invalidate the use of lower dimensional formulations and methods...

The recovery of chargeability information from inductive sources is treated as a workflow process with the following steps: (a) invert early time, non-IP-contaminated, responses to obtain a background conductivity; (b) compute raw dIP data by subtracting the forward modelled TEM responses from the observations; (c) process (possibly) the raw dIP da...

Carbon dioxide injection monitoring in offshore environments is a promising future application of the marine controlled-source electromagnetic (mCSEM) method. To investigate whether the mCSEM method can be used to quantitatively monitor variations in the distribution of the injected CO2, we developed a mCSEM inversion scheme and conducted numerical...

In this paper we propose a methodology to generate a 3D dis-tribution of pseudo-chargeability from airborne time domain electromagnetic data. The processing flow is as follows: (a) Invert the TEM data to generate a background conductivity. This may involve omitting data that are obviously contami-nated with IP signals, such as the existence of nega...

The magnetic and electromagnetic responses from airborne systems at Tli Kwi Cho, a kimberlite complex in the Northwest Territories, Canada, have received considerable attention over the last two decades but a complete understanding of the causative physical properties is not yet at hand. Our analysis is distributed among three posters. In the first...

The magnetic and electromagnetic responses from airborne systems at Tli Kwi Cho, a kimberlite complex in the Northwest Territories, Canada, have received considerable attention over the last two decades but a complete understanding of the causative physical properties is not yet at hand. Our analysis is distributed among three papers. In the first,...

In order to interpret field data from small-loop electromagnetic (EM) instruments with fixed source-receiver separation, 1D inversion method is commonly used due to its efficiency with regard to computation costs. This application of 1D inversion is based on the assumption that small-offset broadband EM signals are insensitive to lateral resistivit...

The feasibility of marine controlled-source Electromagnetic (mCSEM) monitoring for CO2 sequestration could be evaluated by the analysis of EM responses due to injected CO2. However, its capability for the real CO2 sequestration case should be verified by the inversion approach with reasonable monitoring scenario. In this study, we developed a 2.5D...

Reservoir production monitoring using mCSEM has been studied because it is sensitive to resistivity changes resulting from variations in hydrocarbon saturation. However, mCSEM for CO2 sequestration monitoring has scarcely been investigated, although the mCSEM method is advantageous for monitoring CO2 injection and migration because of high correlat...