A5007220451- Seismic Waves and Analysis
- Geophysical and Geoelectrical Methods
- Geophysical Methods and Applications
- Seismic Imaging and Inversion Techniques
- Earthquake Detection and Analysis
- Geophysics and Sensor Technology
- earthquake and tectonic studies
- Seismology and Earthquake Studies
- Underwater Acoustics Research
- Reservoir Engineering and Simulation Methods
- Methane Hydrates and Related Phenomena
- Drilling and Well Engineering
- Electrokinetic Soil Remediation Techniques
- Landslides and related hazards
- Cryospheric studies and observations
- Anomaly Detection Techniques and Applications
- Neural Networks and Applications
- Hydrological Forecasting Using AI
- Computational Physics and Python Applications
- Advanced Computational Techniques and Applications
- Structural Health Monitoring Techniques
- Ultrasonics and Acoustic Wave Propagation
- Groundwater and Isotope Geochemistry
- Coastal and Marine Dynamics
- Geological Formations and Processes Exploration
University of Hawaiʻi at Mānoa
2018-2023
University of Hawaii System
2018-2023
Delft University of Technology
2012-2020
Massachusetts Institute of Technology
2017-2020
Society of Exploration Geophysicists
2019
Abstract We study if nature can help us overcome the very low signal‐to‐noise ratio of seismo‐electromagnetic converted fields by investigating effects thin‐bed geological structures on signal. To investigate bed thinning interference patterns, we numerically simulate wave propagation through horizontally layered media with different amounts and thicknesses thin beds. distinguish two limits thickness. Below upper limit, package beds starts acting like an “effective” medium. lower further...
The Schofield groundwater body on the island of Oʻahu is one most important freshwater reservoirs yet has enigmatically high hydraulic head as compared to adjacent basal water bodies. Various hypotheses have been proposed explain this so-called North Dam, for part aquifer’s remains unexplained. For study we collected extensive self-potential and seismic ambient noise datasets in an effort better understand geologic fluid flow conditions across Dam boundary.  We 40...
We designed and developed an experimental setup in which acoustic to electromagnetic (EM) wave conversions at interfaces can be measured. Theoretical results are obtained with electrokinetic full‐waveform theoretical model, where use was made of the Sommerfeld approach. Using bimodal samples, different fluid–solid interface effects saturating fluids were investigated. The contrast between water water‐saturated porous glass samples is larger than oil‐saturated samples. Fontainebleau sandstone...
We have developed a comprehensive methodology for the acquisition and processing of self-potential (SP) data, as well some keys interpretation results. The wide applicability SP method its low cost make it popular to use in variety natural environments. Despite versatility fact that various published journal papers describe applications, we believe there is an important need dedicated, peer-reviewed acquisition, processing, visualization/interpretation paper scientific literature. identified...
Abstract For induced seismicity, the non-stationary, heterogeneous character of subsurface stress perturbations can be a source spatiotemporal variations in scaling event sizes; one critical parameters controlling seismic hazard and risk. We demonstrate test systematic, statistical, penalized-likelihood approach to analysing both spatial temporal size distributions. The methodology used is transferable risk analysis any operation, especially for small earthquake catalogues. explore whole...
We experimentally validate a relatively recent electrokinetic formulation of the streaming potential (SP) coefficient as developed by Pride (1994). The start our investigation focuses on coefficient, which gives rise to coupling mechanical and electromagnetic fields. It is found that theoretical amplitude values this dynamic SP are in good agreement with normalized experimental results over wide frequency range, assuming no dependence bulk conductivity. By adopting full set equations,...
We demonstrate the value of using self-potential method to study volcanic environments, and particularly fluid flow in those environments. showcase fact that measurements are a highly efficient way map large areas systems under challenging terrain conditions, where other geophysical techniques may be or expensive deploy. Using case studies variety volcano types, including tuff cones, shield volcanoes, stratovolcanoes, monogenetic fields, we emphasize signals enable us settings on multiple...
We have developed an analytically based, energy fluxnormalized numerical modeling code (ESSEMOD), capable of the wave propagation all existing ElectroSeismic and SeismoElectric source-receiver combinations in horizontally layered configurations. compare results several these modeled a homogeneous medium with explicitly derived space Green's function solutions, order to be able validate ESSEMOD both arrival times amplitudes. Especially amplitudes are important due fact that main reason...
We study the accuracy and numerical stability of three eigenvector sets for modelling coupled poroelastic electromagnetic layered-Earth response. use a known set, its flux-normalized version newly derived set. The new set is chosen such that system properly uncoupled when coupling between fields vanishes. carry out two different tests: first test focuses on internal system, eigenvalue consistency; second investigates preciseness systems by looking at identity relations. find shows largest...
Summary The seismoelectric effect can be of importance for hydrocarbon exploration as it is complementary to conventional seismics. Besides enabling seismic resolution and electromagnetic sensitivity at the same time, method also provide us with additional, high-value information like porosity permeability. However, very little still understood this complex physical phenomenon. Therefore, crucial able perform numerical modeling experiments carefully investigate parameters that play a role....
ABSTRACT Wavefield decomposition forms an important ingredient of various geophysical methods. An example wavefield is the into upgoing and downgoing wavefields simultaneous different wave/field types. The multi‐component field scheme makes use recordings quantities (such as particle velocity pressure). In practice, can be obscured by sensor characteristics, requiring calibration with unknown factor. Not all required for might available, or they suffer from noise levels. multi‐depth‐level...
Abstract We study a watershed containing an old stream valley at the Kaiwi Coast on Oʻahu, Hawaiʻi. The site has undergone significant hydrogeological changes throughout its history, and present displays complex interactions of variety geological formations. highlight innovative efficient combination two hydrogeophysical methodologies for studying groundwater systems: ambient noise surface wave tomography (ANSWT), self‐potential (SP) measurements. collected (1) 5 days continuous seismic...
SUMMARY The induced seismicity in the Groningen gas field, Netherlands, presents contrasted spatio-temporal patterns between central area and south west area. Understanding origin of this contrast requires a thorough assessment two factors: (1) stress development on faults (2) frictional response to stresses. Both factors have large uncertainties that must be honoured then reduced with observational constraints. Ensembles realizations are built by varying Poisson's ratio poro-elastic model...
Summary We compare the coupled Marchenko equations without free-surface multiples to including multiples. When using conventional method of iterative substitution solve these equations, a difference in convergence behaviour is observed, suggesting that there fundamental underlying dynamics. Both an intuitive explanation, based on interferometric interpretation, as well mathematical confirm this difference, and suggest might not be most suitable for solving system Therefore, alternative...
We present a novel method to transform seismic data with sources at the surface and receivers above below selected target zone in subsurface into virtual located initial receiver locations. The is based on inverting series of multidimensional equations convolution- correlation-type. required input can be computed from new iterative scheme that currently being developed. output contains illuminate not only (as original data), but also below, facilitating needs imaging inversion an optimal...
In this thesis, I study coupled poroelastic waves and electromagnetic fields in layered media. The focus is two-fold: 1. Increase the theoretical physical understanding of seismo-electromagnetic phenomenon by analytically-based numerical modeling. 2. Investigate potential interferometry. After presenting governing equations that form basis framework, capture system into a matrix-vector representation wave equation. first use literature eigenvector sets, which normalize with respect to...
We present a new approach to apply wavefield decomposition, illustrated for an energy flux-normalized elastodynamic case. start by considering situation where two horizontal boreholes are closely separated from each other. By recording only the particle velocities at both depth levels (for example with conventional 3-component geophones) and expressing one-way wavefields one level in terms of fields other level, inverse problem can be formulated solved. This multi-depth level(MDL)...
Summary Increasing industrial and societal challenges demand a continuous need for improved imaging methods. In recent years, quite some research has been performed on using seismoelectric phenomena geophysical exploration imaging. Like the other methods, technique also its drawbacks. Besides fact that physical phenomenon is very complex, one of main low signal-to-noise ratio coupled signals, especially second-order interface response fields. From seismics, it well-known anonamously high...
For multi-parameter problems, such as the seismoelectric system, sensitivity analysis through resolution functions is a low-cost, fast method of determining whether measured fields are sensitive to certain subsurface parameters. We define function for inversion bulk density perturbation. The synthetic data and Green’s required construct computed using modelling code ESSEMOD. First, we consider purely electromagnetic problem with conductivity perturbation at single point in an isotropic...