Geophysical detection of clandestine tunnels is a complex problem that has met with limited success. Multiple methods have been applied, spanning several decades, but reliable solution yet to be found. We evaluated shallow seismic data collected at tunnel test site representative geologic settings found along the southwestern U.S. border. Our results demonstrated capability using P-wave diffraction and surface-wave backscatter techniques detect purpose-built subterranean tunnel. Near-surface...

We have applied time domain 2D full-waveform inversion (FWI) to detect a known 10 m deep wood-framed tunnel at Yuma Proving Ground, Arizona. The acquired seismic data consist of series survey lines that are perpendicular the long axis tunnel. With use an initial model estimated from surface wave methods, void-detection-oriented FWI workflow was applied. A straightforward [Formula: see text] quotient masking method used reduce artifacts and improve confidence in identifying anomalies possess...

We have applied time-domain 3D elastic full-waveform inversion (FWI) to a known tunnel constructed 10 m below the surface with no distinguishing expressions. Multicomponent experiments that use an initial model estimated from wave methods suggest vertical sources and combination of longitudinal receivers result in clearest image tunnel. obtain approximate using 24 720 receivers. find increasing number 216 does not significantly improve details Further experimentation indicates we can detect...

Perimeter-defense operations, geohazard assessment, and engineering characterization require the detection localization of subsurface anomalies. Seismic waves incident upon these discontinuities generate a scattered wavefield. We have developed various surface-wave techniques, currently being fielded, that consistently delivered accurate precise results across wide range survey parameters geographical locations. use multichannel analysis surface approach to study multimode Rayleigh wave,...

This paper presents a novel system combining machine learning (ML) and four dimensional variational data assimilation (4D-var) to enhance the prediction of partial differential equations (PDEs) governing groundwater infiltration through soil concrete. Utilizing Richards' equation, simulated with OpenFOAM, our approach leverages Digital Elevation Model (DEM) files from US Army Corps Engineers (USACE), pre-processed Blender, model initial conditions. By integrating TensorFlow's...

Full-waveform inversion (FWI) is widely used to reconstruct subsurface properties at different geological scales. For shallow land applications using surface waves, a lack of information on the source wavelet, dispersion, and presence higher modes increases nonlinearity inverse problem. Moreover, can become more challenging with near-surface (NS) complexities associated scattering, attenuation, high-contrast variations in elastic parameters. To address those challenges, we exploit potential...

Clandestine tunnels, used for drug or human trafficking and tactical operations, pose a security threat worldwide remain elusive targets detection with geophysical methods. P-wave diffraction imaging is an increasingly common technique detecting subsurface discontinuities that are smaller than the seismic wavelength (such as faults, pinch outs, small voids) has been successfully to detect shallow tunnels. diffractions from tunnels typically have very low signal-to-noise ratios therefore...

Subsurface voids may manifest themselves as natural or anthropogenic dissolution features, illegal cross‐border tunnels, abandoned mines. Detection of these using geophysical methods has often proven difficult due to multiple factors including depth‐to‐diameter ratio, lack resolution, non‐uniqueness, etc. Experiments were conducted at a test site with known subsurface void determine the capability near‐surface seismic applied detection. In this study, refraction tomography and multichannel...

PreviousNext No AccessSEG Technical Program Expanded Abstracts 2014Correlation of the backscatter analysis surface waves method (BASW) for anomaly detectionAuthors: J. Tyler Schwenk*Steven D. SloanRichard MillerJulian IvanovJ. Schwenk*XRI GeophysicsSearch more papers by this author, Steven SloanXRI Richard MillerU KansasSearch and Julian IvanovU authorhttps://doi.org/10.1190/segam2014-1684.1 SectionsSupplemental MaterialAboutPDF/ePub ToolsAdd to favoritesDownload CitationsTrack...

Geophysical detection of near-surface voids caused by mining, tunnels, karst features, etc., is a persistent problem that has not been solved either consistently or across multiple geologic settings. Multiple methods have used with varying degrees success. We present shallow seismic data collected at test site 9.1-m deep tunnel in unconsolidated sediments similar to settings found along the southwest US border. Test results demonstrate capability using P-wave diffraction and surface wave...

Direct and indirect methods of detecting subsurface voids cavities using seismic have proven to be a challenge for the better part century. There are several examples resonance associated with shallow in literature, but many them individual instances or do not include real data, leaving readers wonder if it is an exploitable phenomenon that can used at multiple sites, requires site-specific set criteria generated. We present three observed coincident location known range depths determine...

The cost of three‐dimensional seismic‐reflection surveys is approximately inversely proportional to the square target depth, which renders ultra‐shallow 3‐D uneconomical when employing conventional acquisition methods. We developed instrumentation that automatically deploys an array geophones for efficient shallow seismic reflection data. components are: a rigid‐steel platform used positioning, planting, and transporting geophones; hydraulically controlled mechanism decoupling from during...

The processing of clipped seismic traces may produce high-frequency wavelets that can be misinterpreted as reflections in filtered shot gathers and common-midpoint (CMP) stacked sections. To illustrate this effect, a near-surface CMP reflection survey was conducted using two sources to compare the effects various band-pass frequency filters on traces. An event observed data set replicated filter operators applied, similar effect convolving boxcar function with operator. anomaly exhibited...

Backscattered or reflected surface waves have been demonstrated to be able detect and locate subsurface anomalies in previous studies, including voids faults. Two examples are presented here that show a relatively quick simple way estimate the depth of interpreted based on frequency backscattered events at two field sites with depths 3 m 9.2 m. From practical application-based perspective, fast straightforward method estimating can valuable when turnaround is necessary if confirmation by...

The location of a small 9.2 m deep tunnel is correctly interpreted from diffraction section generated focused SH-wave diffractions. Clandestine tunnels used for drug or human trafficking and tactical operations pose security threat worldwide. Seismic body waves are sensitive to the large contrast in geophysical properties an air-filled tunnel, numerous studies indicate that seismic wavefield interacts with manifests form wave P-wave imaging increasingly common technique detecting subsurface...

ABSTRACT Three‐dimensional ultra‐shallow seismic reflection methods were used to image multiple reflectors less than 20 m deep, including the top of saturated zone, a paleo‐channel feature and bedrock at field site located near Lawrence, Kansas. A small 3D demonstration survey was designed acquired using source receiver intervals 0.5 line 2 m. The had nominal fold 48 covered an area ~15.5 × 35.5 Large variations in velocity present, ranging from ~300–600 m/s laterally shallowest layer...

Near-surface seismic data were collected at multiple sites in Afghanistan to detect and locate subsurface anomalies, including clandestine tunnels. Examples shown here include over the escape tunnel discovered Sarposa prison Kandahar, Afghanistan, that allowed 480 prisoners (data postdiscovery), from another shallow recently an undisclosed location, a couple of subterranean infrastructure examples. The processed without prior knowledge target locations and, case second example, directly...

The use of dissolution wells for mining salt has been common practice over a century, leaving behind brine-filled “salt jugs” or voids in the subsurface which, time, can migrate through overlying rock formations, potentially leading to sinkhole formation and public safety hazards. In an effort determine relative range stress on roof above these jugs at various stages failure, evaluate extent void migration, aid remediation planning, shear-wave reflection surveys were conducted well field...

We collected ultra‐shallow seismic‐reflection data to image the near‐surface stratigraphy of a Kansas River point bar. were successful in identifying discontinuous clay layer and top saturated zone at depths 0.95 1.4 m. Seismic walkaway using various .22‐caliber ammunition show that decreased source energy is necessary generate higher frequencies prevent clipping critical near‐offset traces needed identify reflections. The seismic reflections exhibited average normal moveout velocities...

Summary We have successfully applied 3D elastic full waveform inversion to detect voids in the near surface (within first tens of meters). An active source survey with different combinations sources and several lines multi-component receivers was acquired over an existing tunnel. explained that our synthetic field experiments, low frequency content (below 20 Hz) carries a significant amount back-scattering wave energy from tunnel, which plays major role locating anomaly. shown...

The modern use of clandestine tunnels has antagonized military and law enforcement agencies alike over the past 50 years, not only in their simplicity effectiveness, but also challenges defending against them. Likewise, geophysicists have been confounded, finding what should be a straightforward target on paper — detecting an anomaly with often vastly different physical properties than its surroundings much more difficult task models would suggest. We evaluated half century applied seismic...