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Myung W. Lee

Publications and source records attributed to Myung W. Lee.

At least 19 recordsLinked to original sources
USGS2014

Geological controls on the occurrence of gas hydrate from core, downhole log, and seismic data in the Shenhu area, South China Sea

Multi-channel seismic reflection data, well logs, and recovered sediment cores have been used in this study to characterize the geologic controls on the occurrence of gas hydrate in the Shenhu area of the South China Sea. The concept of the "gas hydrate petroleum system" has allowed for the systematic analysis of the impact of gas source, geologic controls on gas migration, and the role of the host sediment in the formation and stability of gas hydrates as encountered during the 2007 Guangzhou Marine Geological Survey Gas Hydrate Expedition (GMGS-1) in the Shenhu area. Analysis of seismic and bathymetric data identified seventeen sub-linear, near-parallel submarine canyons in this area. These canyons, formed in the Miocene, migrated in a northeasterly direction, and resulted in the burial and abandonment of canyons partially filled by coarse-grained sediments. Downhole wireline log (DWL) data were acquired from eight drill sites and sediment coring was conducted at five of these sites, which revealed the presence of suitable reservoirs for the occurrence of concentrated gas hydrate accumulations. Gas hydrate-bearing sediment layers were identified from well log and core data at three sites mainly within silt and silt clay sediments. Gas hydrate was also discovered in a sand reservoir at one site as inferred from the analysis of the DWL data. Seismic anomalies attributed to the presence of gas below the base of gas hydrate stability zone, provided direct evidence for the migration of gas into the overlying gas hydrate-bearing sedimentary sections. Geochemical analyses of gas samples collected from cores confirmed that the occurrence of gas hydrate in the Shenhu area is controlled by the presence thermogenic methane gas that has migrated into the gas hydrate stability zone from a more deeply buried source.

Shenhu area, South China Sea↗
USGS2014

Gas hydrate identified in sand-rich inferred sedimentary section using downhole logging and seismic data in Shenhu area, South China Sea

Downhole wireline log (DWL) data was acquired from eight drill sites during China's first gas hydrate drilling expedition (GMGS-1) in 2007. Initial analyses of the acquired well log data suggested that there were no significant gas hydrate occurrences at Site SH4. However, the re-examination of the DWL data from Site SH4 indicated that there are two intervals of high resistivity, which could be indicative of gas hydrate. One interval of high resistivity at depth of 171–175 m below seafloor (mbsf) is associated with a high compressional- wave (P-wave) velocities and low gamma ray log values, which suggests the presence of gas hydrate in a potentially sand-rich (low clay content) sedimentary section. The second high resistivity interval at depth of 175–180 mbsf is associated with low P-wave velocities and low gamma values, which suggests the presence of free gas in a potentially sand-rich (low clay content) sedimentary section. Because the occurrence of free gas is much shallower than the expected from the regional depth of the bottom simulating reflector (BSR), the free gas could be from the dissociation of gas hydrate during drilling or there may be a local anomaly in the depth to the base of the gas hydrate stability zone. In order to determine whether the low P-wave velocity with high resistivity is caused by in-situ free gas or dissociated free gas from the gas hydrate, the surface seismic data were also used in this analysis. The log analysis incorporating the surface seismic data through the construction of synthetic seismograms using various models indicated the presence of free gas directly in contact with an overlying gas hydrate-bearing section. The occurrence of the anomalous base of gas hydrate stability at Site SH4 could be caused by a local heat flow conditions. This paper documents the first observation of gas hydrate in what is believed to be a sand-rich sediment in Shenhu area of the South China Sea.

Shenhu↗
USGS2013

Hydration free energies of cyanide and hydroxide ions from molecular dynamics simulations with accurate force fields

The evaluation of hydration free energies is a sensitive test to assess force fields used in atomistic simulations. We showed recently that the vibrational relaxation times, 1D- and 2D-infrared spectroscopies for CN(-) in water can be quantitatively described from molecular dynamics (MD) simulations with multipolar force fields and slightly enlarged van der Waals radii for the C- and N-atoms. To validate such an approach, the present work investigates the solvation free energy of cyanide in water using MD simulations with accurate multipolar electrostatics. It is found that larger van der Waals radii are indeed necessary to obtain results close to the experimental values when a multipolar force field is used. For CN(-), the van der Waals ranges refined in our previous work yield hydration free energy between -72.0 and -77.2 kcal mol(-1), which is in excellent agreement with the experimental data. In addition to the cyanide ion, we also study the hydroxide ion to show that the method used here is readily applicable to similar systems. Hydration free energies are found to sensitively depend on the intermolecular interactions, while bonded interactions are less important, as expected. We also investigate in the present work the possibility of applying the multipolar force field in scoring trajectories generated using computationally inexpensive methods, which should be useful in broader parametrization studies with reduced computational resources, as scoring is much faster than the generation of the trajectories.

Physical Chemistry Chemical Physics↗
USGS2013

Comparison of methods for predicting shear-wave velocities of unconsolidated shallow sediments in the Gulf of Mexico

Accurate shear-wave velocities for shallow sediments are important for a variety of seismic applications such as inver-sion and amplitude versus offset analysis. During the U.S. Department of Energy-sponsored Gas Hydrate Joint Industry Project Leg II, shear-wave velocities were measured at six wells in the Gulf of Mexico using the logging-while-drilling SonicScope acoustic tool. Because the tool measurement point was only 35 feet from the drill bit, the adverse effect of the borehole condition, which is severe for the shallow unconsolidated sediments in the Gulf of Mexico, was mini-mized and accurate shear-wave velocities of unconsolidated sediments were measured. Measured shear-wave velocities were compared with the shear-wave velocities predicted from the compressional-wave velocities using empirical formulas and the rock physics models based on the Biot-Gassmann theory, and the effectiveness of the two prediction methods was evaluated. Although the empirical equation derived from measured shear-wave data is accurate for predicting shear-wave velocities for depths greater than 500 feet in these wells, the three-phase Biot-Gassmann-theory -based theory appears to be optimum for predicting shear-wave velocities for shallow unconsolidated sediments in the Gulf of Mexico.

Gulf Of Mexico↗
USGS2012

Variations in the reflectivity of the moho transition zone beneath the Midcontinent Rift System of North America: results from true amplitude analysis of GLIMPCE data

True amplitude processing of The Great Lakes International Multidisciplinary Program on Crustal Evolution seismic reflection data from the Midcontinent Rift System of North America shows large differences in the reflectivity of the Moho transition zone beneath the axial rift, beneath the rift flanks, and outside of the rift. The Moho reflection from the axial rift has a discontinuous, diffractive character marginally stronger (several decibels) than an otherwise transparent lower crust and upper mantle. Beneath the axial rift, Moho is interpreted to be a synrift igneous feature. Beneath the rift flanks, the reflectivity of the Moho transition is generally well developed with two identifiable boundaries, although in places it is weakly reflective to nonreflective, similar to Moho outside the rift. The two boundaries are interpreted as the base of essentially intact, although stretched, prerift Archean crust (upper boundary) and new synrift Moho 1-2 s (6-7 km) deeper (lower boundary). Beneath the rift flanks, the layered reflection Moho transition results from the preexisting crustal composition and fabric modified by synrift igneous processes and extensional tectonic/metamorphic processes. The geologic evidence for extensive basaltic magmatism in the rift is the basis for interpreting the Moho signature as a Keweenawan structure that has been preserved for 1.1 b.y. Extension and magmatism appear to enhance reflectivity in the lower crust and Moho transition zone only where stretching factors are moderate (rift flanks) and not where they are extreme (axial rift). This leads to the prediction that the reflectivity across analogous volcanic passive continental margins should be greatest beneath the moderately stretched continental shelves and should decrease towards the ocean-continent boundary.

Journal of Geophysical Research B: Solid Earth↗
USGS2012

Limitations of quantitative analysis of deep crustal seismic reflection data: Examples from GLIMPCE

Amplitude preservation in seismic reflection data can be obtained by a relative true amplitude (RTA) processing technique in which the relative strength of reflection amplitudes is preserved vertically as well as horizontally, after compensating for amplitude distortion by near-surface effects and propagation effects. Quantitative analysis of relative true amplitudes of the Great Lakes International Multidisciplinary Program on Crustal Evolution seismic data is hampered by large uncertainties in estimates of the water bottom reflection coefficient and the vertical amplitude correction and by inadequate noise suppression. Processing techniques such as deconvolution, F-K filtering, and migration significantly change the overall shape of amplitude curves and hence calculation of reflection coefficients and average reflectance. Thus lithological interpretation of deep crustal seismic data based on the absolute value of estimated reflection strength alone is meaningless. The relative strength of individual events, however, is preserved on curves generated at different stages in the processing. We suggest that qualitative comparisons of relative strength, if used carefully, provide a meaningful measure of variations in reflectivity. Simple theoretical models indicate that peg-leg multiples rather than water bottom multiples are the most severe source of noise contamination. These multiples are extremely difficult to remove when the water bottom reflection coefficient is large (>0.6), a condition that exists beneath parts of Lake Superior and most of Lake Huron.

Great Lakes↗
USGS2012

Antioxidant effects of selenium on lung injury in paraquat intoxicated rats

CONTEXT: Paraquat (PQ) causes lethal intoxication by inducing oxidant injury to the lung. Selenium is a cofactor for glutathione peroxidase (GPx), which is one of the major endogenous antioxidant enzymes. OBJECTIVE: To determine whether selenium post-treatment activates GPx, decreases lung injury, and improves survival in PQ intoxicated rats. MATERIALS AND METHODS: Male Spraque-Dawley rats were categorized into three groups: sham (n = 6), PQ (n = 12), and PQ + Se (n = 12). In the PQ and PQ + Se groups, 50 mg/kg of PQ was administered intraperitoneally. After 10 minutes, 60 μg/kg of Se (PQ + Se) or saline (PQ) was administered via the tail vein. Six rats per group were euthanized 6 hours or 24 hours later. Lung tissues were harvested for the measurement of GPx activity, reduced glutathione (GSH), glutathione disulfide (GSSG) and malondialdehyde (MDA) and for histological analysis. Using separated set of rats, survival of PQ (n = 10) and PQ + Se (n = 10) were observed for 72 hours. RESULTS: GPx activity in the PQ group at the 6-hour and 24-hour time points was lower than in the sham group (p < 0.006). GPx activity in the PQ + Se group at the 6-hour and 24-hour time points was higher than in the PQ group at the same time (p < 0.006). GPx activity in the PQ + Se group at 24 hours was higher than at 6-hour time point and also higher than in the sham group (p < 0.006). The GSH/GSSG ratio in the PQ + Se group at 24 hours was lower than that in the sham group (p < 0.006). MDA levels in the PQ group at 6 hours and 24 hours were higher than in the sham group (p < 0.006). MDA levels at 24 hours in the PQ + Se group was lower than in the PQ group (p < 0.006). Acute lung injury (ALI) scores in the PQ group at 6 hours and 24 hours were higher than in the sham group (p < 0.006). ALI scores at 24 hours in the PQ + Se group were lower than in the PQ group. Survival rates did not differ between PQ and PQ + Se (p = 0.869). CONCLUSION: Single dose of selenium post-treatment activates GPx and attenuates lipid peroxidation and lung injury early after paraquat intoxication, but does not improve 72 hours of survival.

Clinical Toxicology↗
USGS2012

Evaluation of long-term gas hydrate production testing locations on the Alaska North Slope

The results of short-duration formation tests in northern Alaska and Canada have further documented the energy-resource potential of gas hydrates and have justified the need for long-term gas-hydrate-production testing. Additional data acquisition and long-term production testing could improve the understanding of the response of naturally occurring gas hydrate to depressurization-induced or thermal-, chemical-, or mechanical-stimulated dissociation of gas hydrate into producible gas. The Eileen gashydrate accumulation located in the Greater Prudhoe Bay area in northern Alaska has become a focal point for gas-hydrate geologic and production studies. BP Exploration (Alaska) Incorporated and ConocoPhillips have each established research partnerships with the US Department of Energy to assess the production potential of gas hydrates in northern Alaska. A critical goal of these efforts is to identify the most suitable site for production testing. A total of seven potential locations in the Prudhoe Bay, Kuparuk River, and Milne Point production units were identified and assessed relative to their suitability as a long-term gas-hydrate-production test sites. The test-site-assessment criteria included the analysis of the geologic risk associated with encountering reservoirs for gas-hydrate testing. The site-selection process also dealt with the assessment of the operational/logistical risk associated with each of the potential test sites. From this review, a site in the Prudhoe Bay production unit was determined to be the best location for extended gas-hydrate-production testing. The work presented in this report identifies the key features of the potential test site in the Greater Prudhoe Bay area and provides new information on the nature of gas-hydrate occurrence and the potential impact of production testing on existing infrastructure at the most favorable sites. These data were obtained from well-log analysis, geological correlation and mapping, and numerical simulation.

Alaska↗
USGS2012

Metformin prevents endoplasmic reticulum stress-induced apoptosis through AMPK-PI3K-c-Jun NH2 pathway

Type 2 diabetes mellitus is thought to be partially associated with endoplasmic reticulum (ER) stress toxicity on pancreatic beta cells and the result of decreased insulin synthesis and secretion. In this study, we showed that a well-known insulin sensitizer, metformin, directly protects against dysfunction and death of ER stress-induced NIT-1 cells (a mouse pancreatic beta cell line) via AMP-activated protein kinase (AMPK) and phosphatidylinositol-3 (PI3) kinase activation. We also showed that exposure of NIT-1 cells to metformin (5mM) increases cellular resistance against ER stress-induced NIT-1 cell dysfunction and death. AMPK and PI3 kinase inhibitors abolished the effect of metformin on cell function and death. Metformin-mediated protective effects on ER stress-induced apoptosis were not a result of an unfolded protein response or the induced inhibitors of apoptotic proteins. In addition, we showed that exposure of ER stressed-induced NIT-1 cells to metformin decreases the phosphorylation of c-Jun NH(2) terminal kinase (JNK). These data suggest that metformin is an important determinant of ER stress-induced apoptosis in NIT-1 cells and may have implications for ER stress-mediated pancreatic beta cell destruction via regulation of the AMPK-PI3 kinase-JNK pathway.

Biochemical and Biophysical Research Communication↗
USGS2012

SIRT1 attenuates palmitate-induced endoplasmic reticulum stress and insulin resistance in HepG2 cells via induction of oxygen-regulated protein 150

Endoplasmic reticulum (ER) stress has been implicated in the pathology of type 2 diabetes mellitus (T2DM). Although SIRT1 has a therapeutic effect on T2DM, the mechanisms by which SIRT1 ameliorates insulin resistance (IR) remain unclear. In this study, we investigated the impact of SIRT1 on palmitate-induced ER stress in HepG2 cells and its underlying signal pathway. Treatment with resveratrol, a SIRT1 activator significantly inhibited palmitate-induced ER stress, leading to the protection against palmitate-induced ER stress and insulin resistance. Resveratrol and SIRT1 overexpression induced the expression of oxygen-regulated protein (ORP) 150 in HepG2 cells. Forkhead box O1 (FOXO1) was involved in the regulation of ORP150 expression because suppression of FOXO1 inhibited the induction of ORP150 by SIRT1. Our results indicate a novel mechanism by which SIRT1 regulates ER stress by overexpression of ORP150, and suggest that SIRT1 ameliorates palmitate-induced insulin resistance in HepG2 cells via regulation of ER stress.

Biochemical and Biophysical Research Communication↗
USGS2012

Anisotropic models to account for large borehole washouts to estimate gas hydrate saturations in the Gulf of Mexico Gas Hydrate Joint Industry Project Leg II Alaminos 21 B well

Through the use of 3-D seismic amplitude mapping, several gashydrate prospects were identified in the Alaminos Canyon (AC) area of the Gulf of Mexico. Two locations were drilled as part of the Gulf of MexicoGasHydrate Joint Industry Project Leg II (JIP Leg II) in May of 2009 and a comprehensive set of logging-while-drilling (LWD) logs were acquired at each well site. LWD logs indicated that resistivity in the range of ~2 ohm-m and P-wave velocity in the range of ~1.9 km/s were measured in the target sand interval between 515 and 645 feet below sea floor. These values were slightly elevated relative to those measured in the sediment above and below the target sand. However, the initial well log analysis was inconclusive regarding the presence of gashydrate in the logged sand interval, mainly because largewashouts caused by drilling in the target interval degraded confidence in the well log measurements. To assess gashydratesaturations in the sedimentary section drilled in the Alaminos Canyon 21B (AC21-B) well, a method of compensating for the effect of washouts on the resistivity and acoustic velocities was developed. The proposed method models the washed-out portion of the borehole as a vertical layer filled with sea water (drilling fluid) and the apparent anisotropic resistivity and velocities caused by a vertical layer are used to correct the measured log values. By incorporating the conventional marine seismic data into the well log analysis, the average gashydratesaturation in the target sand section in the AC21-Bwell can be constrained to the range of 8&ndash;28%, with 20% being our best estimate.

Gulf Of Mexico;Alaminos Canyon↗
USGS2012

Pore- and fracture-filling gas hydrate reservoirs in the Gulf of Mexico Gas Hydrate Joint Industry Project Leg II Green Canyon 955 H well

High-quality logging-while-drilling (LWD) downhole logs were acquired in seven wells drilled during the Gulf of MexicoGasHydrateJointIndustryProjectLegII in the spring of 2009. Well logs obtained in one of the wells, the GreenCanyon Block 955Hwell (GC955-H), indicate that a 27.4-m thick zone at the depth of 428 m below sea floor (mbsf; 1404 feet below sea floor (fbsf)) contains gashydrate within sand with average gashydrate saturations estimated at 60% from the compressional-wave (P-wave) velocity and 65% (locally more than 80%) from resistivity logs if the gashydrate is assumed to be uniformly distributed in this mostly sand-rich section. Similar analysis, however, of log data from a shallow clay-rich interval between 183 and 366 mbsf (600 and 1200 fbsf) yielded average gashydrate saturations of about 20% from the resistivity log (locally 50-60%) and negligible amounts of gashydrate from the P-wave velocity logs. Differences in saturations estimated between resistivity and P-wave velocities within the upper clay-rich interval are caused by the nature of the gashydrate occurrences. In the case of the shallow clay-rich interval, gashydrate fills vertical (or high angle) fractures in rather than fillingpore space in sands. In this study, isotropic and anisotropic resistivity and velocity models are used to analyze the occurrence of gashydrate within both the clay-rich and sand dominated gas-hydrate-bearing reservoirs in the GC955-Hwell.

Gulf Of Mexico↗
USGS2012

Gulf of Mexico Gas Hydrate Joint Industry Project Leg II logging-while-drilling data acquisition and analysis

One of the objectives of the Gulf of Mexico Gas Hydrate Joint Industry Project Leg II (GOM JIP Leg II) was the collection of a comprehensive suite of logging-while-drilling (LWD) data within gas-hydrate-bearing sand reservoirs in order to make accurate estimates of the concentration of gas hydrates under various geologic conditions and to understand the geologic controls on the occurrence of gas hydrate at each of the sites drilled during this expedition. The LWD sensors just above the drill bit provided important information on the nature of the sediments and the occurrence of gas hydrate. There has been significant advancements in the use of downhole well-logging tools to acquire detailed information on the occurrence of gas hydrate in nature: From using electrical resistivity and acoustic logs to identify gas hydrate occurrences in wells to where wireline and advanced logging-while-drilling tools are routinely used to examine the petrophysical nature of gas hydrate reservoirs and the distribution and concentration of gas hydrates within various complex reservoir systems. Recent integrated sediment coring and well-log studies have confirmed that electrical resistivity and acoustic velocity data can yield accurate gas hydrate saturations in sediment grain supported (isotropic) systems such as sand reservoirs, but more advanced log analysis models are required to characterize gas hydrate in fractured (anisotropic) reservoir systems. In support of the GOM JIP Leg II effort, well-log data montages have been compiled and presented in this report which includes downhole logs obtained from all seven wells drilled during this expedition with a focus on identifying and characterizing the potential gas-hydrate-bearing sedimentary section in each of the wells. Also presented and reviewed in this report are the gas-hydrate saturation and sediment porosity logs for each of the wells as calculated from available downhole well logs.

Gulf Of Mexico↗
USGS2012

All solution processed organic thin film transistor-backplane with printing technology for electrophoretic display

In this study, solution processes were developed for backplane using an organic thin film transistor (OTFT) as a driving device for an electrophoretic display (EPD) panel. The processes covered not only the key device of OTFTs but also interlayer and pixel electrodes. The various materials and printing processes were adopted to achieve the requirements of devices and functioning layers. The performance of OTFT of the backplane was sufficient to drive EPD sheet by producing a mobility of 0.12 cm2/v x sec and on/off current ratio of 10(5).

Journal of Nanoscience and Nanotechnology↗
USGS2012

Isotropic, anisotropic, and borehole washout analyses in Gulf of Mexico Gas Hydrate Joint Industry Project Leg II, Alaminos Canyon well 21-A

Through the use of three-dimensional seismic amplitude mapping, several gas hydrate prospects were identified in the Alaminos Canyon area of the Gulf of Mexico. Two of the prospects were drilled as part of the Gulf of Mexico Gas Hydrate Joint Industry Program Leg II in May 2009, and a suite of logging-while-drilling logs was acquired at each well site. Logging-while-drilling logs at the Alaminos Canyon 21&ndash;A site indicate that resistivities of approximately 2 ohm-meter and P-wave velocities of approximately 1.9 kilometers per second were measured in a possible gas-hydrate-bearing target sand interval between 540 and 632 feet below the sea floor. These values are slightly elevated relative to those measured in the hydrate-free sediment surrounding the sands. The initial well log analysis is inconclusive in determining the presence of gas hydrate in the logged sand interval, mainly because large washouts in the target interval degraded well log measurements. To assess gas-hydrate saturations, a method of compensating for the effect of washouts on the resistivity and acoustic velocities is required. To meet this need, a method is presented that models the washed-out portion of the borehole as a vertical layer filled with seawater (drilling fluid). Owing to the anisotropic nature of this geometry, the apparent anisotropic resistivities and velocities caused by the vertical layer are used to correct measured log values. By incorporating the conventional marine seismic data into the well log analysis of the washout-corrected well logs, the gas-hydrate saturation at well site AC21&ndash;A was estimated to be in the range of 13 percent. Because gas hydrates in the vertical fractures were observed, anisotropic rock physics models were also applied to estimate gas-hydrate saturations.

Scientific Investigations Report↗
USGS2012

Well log characterization of natural gas-hydrates

In the last 25 years there have been significant advancements in the use of well-logging tools to acquire detailed information on the occurrence of gas hydrates in nature: whereas wireline electrical resistivity and acoustic logs were formerly used to identify gas-hydrate occurrences in wells drilled in Arctic permafrost environments, more advanced wireline and logging-while-drilling (LWD) tools are now routinely used to examine the petrophysical nature of gas-hydrate reservoirs and the distribution and concentration of gas hydrates within various complex reservoir systems. Resistivity- and acoustic-logging tools are the most widely used for estimating the gas-hydrate content (i.e., reservoir saturations) in various sediment types and geologic settings. Recent integrated sediment coring and well-log studies have confirmed that electrical-resistivity and acoustic-velocity data can yield accurate gas-hydrate saturations in sediment grain-supported (isotropic) systems such as sand reservoirs, but more advanced log-analysis models are required to characterize gas hydrate in fractured (anisotropic) reservoir systems. New well-logging tools designed to make directionally oriented acoustic and propagation-resistivity log measurements provide the data needed to analyze the acoustic and electrical anisotropic properties of both highly interbedded and fracture-dominated gas-hydrate reservoirs. Advancements in nuclear magnetic resonance (NMR) logging and wireline formation testing (WFT) also allow for the characterization of gas hydrate at the pore scale. Integrated NMR and formation testing studies from northern Canada and Alaska have yielded valuable insight into how gas hydrates are physically distributed in sediments and the occurrence and nature of pore fluids(i.e., free water along with clay- and capillary-bound water) in gas-hydrate-bearing reservoirs. Information on the distribution of gas hydrate at the pore scale has provided invaluable insight on the mechanisms controlling the formation and occurrence of gas hydrate in nature along with data on gas-hydrate reservoir properties (i.e., porosities and permeabilities) needed to accurately predict gas production rates for various gas-hydrate production schemes.

Book↗
USGS2011

Anomalous waveforms observed in laboratory-formed gas hydrate-bearing and ice-bearing sediments

Acoustic transmission measurements of compressional, P, and shear, S, wave velocities rely on correctly identifying the P- and S-body wave arrivals in the measured waveform. In cylindrical samples for which the sample is much longer than the acoustic wavelength, these body waves can be obscured by high-amplitude waveform features arriving just after the relatively small-amplitude P-body wave. In this study, a normal mode approach is used to analyze this type of waveform, observed in sediment containing gas hydrate or ice. This analysis extends an existing normal-mode waveform propagation theory by including the effects of the confining medium surrounding the sample, and provides guidelines for estimating S-wave velocities from waveforms containing multiple large-amplitude arrivals.

Journal of the Acoustical Society of America↗