Stratigraphic Analysis with Refraction Tomography
Near-surface seismic refraction tomography imaged the basal contact of the Upper Cambrian silica-rich Mt. Simon Formation with that of the underlying Precambrian granite in central Wisconsin. The discrimination between the Mt. Simon and underlying non-conformable contact with Precambrian rocks was based upon a p-wave velocity of 1,700 m/s. Refraction tomography imaged deep….Read More
Avoiding Caverns in the Arbuckle Mountains Using Electrical Imaging Methods
The Arbuckle Mountains in Oklahoma are a unique province with nearly vertical dipping beds of the Upper Cambrian to Lower Ordovician Arbuckle Group. The Arbuckle Group consists of intercalated sequences of thick carbonates and thinner shales and sandstones. Syn-Pennsylvanian mountain building steeply tilted these beds. Subsequently, caves and voids developed within the carbonate beds, presumably by hypogene speleogenesis…Read More
Subsurface Geophysical Investigation at the Tesla Wardenclyffe Site
Before the turn of the twentieth century, Nikola Tesla experimented with inducing a frequency into the earth to transmit electric current, wirelessly, to distant receivers. Tesla built a laboratory and tower with underground tunnels in the town of Shoreham, New York from 1902 to 1903. He called the site Wardenclyffe but the nature and purpose of the underground tunnels to the 57-m tall tower remain a mystery to this day…Read More
A Comparison of Surface and Standard Penetration Test Derived Shear-Wave Velocitynsic Analysis of Landfills Using EM Methods
Electromagnetic terrain conductivity mapping is an effective method for delineating a landfill’s footprint. The degradation of putrescible material increases the conductivity of the integrated water by the generation of soluble ions. Burn pits contain limited to no concentrations of putrescible material; instead, burn pits contain elevated concentrations of refractory waste and metal…Read More
Forensic Analysis of Landfills Using EM Methods
Electromagnetic terrain conductivity mapping is an effective method for delineating a landfill’s footprint. The degradation of putrescible material increases the conductivity of the integrated water by the generation of soluble ions. Burn pits contain limited to no concentrations of putrescible material; instead, burn pits contain elevated concentrations of refractory waste and metal…Read More
3D Mapping with MASW
One-dimensional Multichannel Analysis of Surface Waves (MASW) seismic test is a quick and accurate sounding technique to collect (Vs) at depth. Combining a series of MASW-derived Vs soundings from specific depths is a convenient and cost effective method of creating 3D maps….Read More
Maximizing Groundwater Production Through VLF Mapping Methods
Random drilling for commercially-productive groundwater wells is a haphazard method within the Pennsylvanian-aged rocks of the Appalachian Plateau Region of southwestern Pennsylvania. These rocks have low permeability and porosity and the average production well produces only enough yield for homeowner use…Read More
Patent: Anvil Shear Wave Generator
THG Geophysics has just been awarded a patent for our Anvil Shear Wave Generator (ASWG).
The present patent application relates to a seismic energy source configured to generate shear wave energy in order to more accurately determine the distribution and orientation of fractures and other features in the subsurface among other uses…Read More
Deep-Mine Void Detection through Electrical Imaging
Electrical imaging can be an effective geophysical method for locating subsurface voids, specifically for deep-mine void detection…Read More
Case Studies of Mine Voids Using Continuous Vertical Electrical Sounding Methods
Deep-mining for clay in St. Marys, Pennsylvania, an unusual and unexpected deep-mined rock type, proved to be a potentially hazardous threat to a proposed subdivision. The 7-meter thick sandstone overlying a 140-year old mine void in the Akron, Ohio area is slowly collapsing and subsidence may adversely impact roads and residences…Read More
Geophysical Applications to Groundwater Resources
Water is a valuable resource and a necessary staple to sustain life. Although water covers more than 75 percent of the earth’s surface, potable water is not always easily accessible. Random drilling is frequently used to locate this resource, often with disappointing results…Read More
VLF Surveying to Delineate Longwall Mine-Induced Fractures
Very low frequency (VLF) surveying is an effective method for detecting long, straight, electrically charged conductors, and it has been used to locate fractures, image subsurface voids, map landfill margins, and to delineate buried conductive utilities…Read More
GPR as a Sentinel Device
Geophysical methods provide a non-destructive non-intrusive method of subsurface investigation. Oftentimes, however, the target is difficult to “see” due to lack of contrast between the target and background…Read More
Subsurface Imaging Using Non-Intrusive Ground Penetrating Radar
Many cemetery operators are faced with limited space and a growing demand for burial plots. Some have chosen to install mausoleums as a mechanism to address this need. Unfortunately, documentation of plot locations can be limited on older portions of cemeteries, thus limiting development of the property…Read More
Geophysical Imaging Techniques as a Screening Tool
Geophysical studies provide an inverse solution to the resolution of environmental problems, and are analogous to a murder mystery investigation. In a murder investigation, we know a murder occurred, but don’t know the cause (i.e., the murderer or weapon)…Read More
Ground Water Purveying Using VLF
Random drilling for commercially-productive groundwater wells is a haphazard method within the Pennsylvanian-aged rocks of the Appalachian Plateau Region of southwestern Pennsylvania. These rocks have low permeability and porosity and the average production well produces only enough yield for homeowner use…Read More
Electrical Imaging of Triassic Fault System
Continuous vertical electrical sounding (CVES) imaged early Triassic normal faults on the southeastern side of Mount Arlington Ridge, part of the northeast-southwest trending ridges within the New Jersey Highlands physiographic province of north-central New Jersey…Read More
Field Applications of MASW Data
One-dimensional multi-spectral analyses of surface waves (MASW) are used to predict subsurface shear-wave interval velocities. Shear wave velocities can also extract additional velocity-related information such as mechanical properties of soils and rocks…Read More
Seismic Reflection in Urban Settings
Seismic reflection multi-stacked (MSF) data can be used in an urban environment for imaging the subsurface, since MSF data are not plagued by noise from an active city…Read More
Geophysical Applications to Solid Waste Analysis
Case studies of regional landfills show that electromagnetic geophysical methods can accurately and inexpensively define boundaries and thickness of waste. Degradation of putrescible solid waste generates conductive leachate that can be imaged with a frequency-domain terrain conductivity meter…Read More
Electric Log Analysis of Precambrian Igneous and Metamorphic Rocks
Electric log, core, and optical petrographic analysis of a metamorphosed and deformed PreCambrian-aged rhyolite effusive event identified 2 litho-facies and effected characterization of the rock deformation. Single-point resistance (SPR) and spontaneous potential (SP) electric logs identified the ubiquitous clay seams and localized dikes…Read More