Nonstretch NMO

Geophysics ◽  
2004 ◽  
Vol 69 (2) ◽  
pp. 599-607 ◽  
Author(s):  
Hervé Perroud ◽  
Martin Tygel

We describe a new implementation of the normal‐moveout (NMO) correction that is routinely applied to common‐midpoint (CMP) reflections prior to stacking. The procedure, called nonstretch NMO, automatically avoids the undesirable stretch effects that are present in conventional NMO. Under nonstretch NMO, a significant range of large offsets that normally would be muted in the case of conventional NMO can be kept and used, thereby leading to better stack and velocity determinations. We illustrate the use of nonstretch NMO by applying it to synthetic and real data sets obtained from high‐resolution (HR) seismic and ground‐penetrating radar (GPR) measurements.

Geophysics ◽  
2015 ◽  
Vol 80 (2) ◽  
pp. H13-H22 ◽  
Author(s):  
Saulo S. Martins ◽  
Jandyr M. Travassos

Most of the data acquisition in ground-penetrating radar is done along fixed-offset profiles, in which velocity is known only at isolated points in the survey area, at the locations of variable offset gathers such as a common midpoint. We have constructed sparse, heavily aliased, variable offset gathers from several fixed-offset, collinear, profiles. We interpolated those gathers to produce properly sampled counterparts, thus pushing data beyond aliasing. The interpolation methodology estimated nonstationary, adaptive, filter coefficients at all trace locations, including at the missing traces’ corresponding positions, filled with zeroed traces. This is followed by an inversion problem that uses the previously estimated filter coefficients to insert the new, interpolated, traces between the original ones. We extended this two-step strategy to data interpolation by employing a device in which we used filter coefficients from a denser variable offset gather to interpolate the missing traces on a few independently constructed gathers. We applied the methodology on synthetic and real data sets, the latter acquired in the interior of the Antarctic continent. The variable-offset interpolated data opened the door to prestack processing, making feasible the production of a prestack time migrated section and a 2D velocity model for the entire profile. Notwithstanding, we have used a data set obtained in Antarctica; there is no reason the same methodology could not be used somewhere else.


2014 ◽  
Vol 543-547 ◽  
pp. 2609-2613 ◽  
Author(s):  
Lu Huang ◽  
Peng Yu Wang ◽  
Qian Song

Compressive sensing (CS) theory asserts that one can recover original signals from far fewer random samples under the condition of being sparse. CS theory is applied to high resolution imaging of vehicle-mounted stepped-frequency forward-looking ground-penetrating radar. This paper explores an approach of obtaining discrete scattering structure of the metal mine based on CS imaging and extracting geometry parameters to discriminate targets. Real data of vehicle-mounted stepped-frequency forward-looking ground-penetrating radar is processed. High resolution images of the metal mine with double-scattering structure are obtained. The feasibility of the method is tested through these images.


2020 ◽  
Vol 12 (10) ◽  
pp. 1583 ◽  
Author(s):  
Immo Trinks ◽  
Alois Hinterleitner

Under suitable conditions, ground-penetrating radar (GPR) measurements harbour great potential for the non-invasive mapping and three-dimensional investigation of buried archaeological remains. Current GPR data visualisations almost exclusively focus on the imaging of GPR reflection amplitudes. Ideally, the resulting amplitude maps show subsurface structures of archaeological interest in plan view. However, there exist situations in which, despite the presence of buried archaeological remains, hardly any corresponding anomalies can be observed in the GPR time- or depth-slice amplitude images. Following the promising examples set by seismic attribute analysis in the field of exploration seismology, it should be possible to exploit other attributes than merely amplitude values for the enhanced imaging of subsurface structures expressed in GPR data. Coherence is the seismic attribute that is a measure for the discontinuity between adjacent traces in post-stack seismic data volumes. Seismic coherence analysis is directly transferable to common high-resolution 3D GPR data sets. We demonstrate, how under the right circumstances, trace discontinuity analysis can substantially enhance the imaging of structural information contained in GPR data. In certain cases, considerably improved data visualisations are achievable, facilitating subsequent data interpretation. We present GPR trace coherence imaging examples taken from extensive, high-resolution archaeological prospection GPR data sets.


2021 ◽  
Vol 13 (12) ◽  
pp. 2384
Author(s):  
Roland Filzwieser ◽  
Vujadin Ivanišević ◽  
Geert J. Verhoeven ◽  
Christian Gugl ◽  
Klaus Löcker ◽  
...  

Large parts of the urban layout of the abandoned Roman town of Bassianae (in present-day Serbia) are still discernible on the surface today due to the deliberate and targeted quarrying of the Roman foundations. In 2014, all of the town's intramural (and some extramural) areas were surveyed using aerial photography, ground-penetrating radar, and magnetometry to analyze the site's topography and to map remaining buried structures. The surveys showed a strong agreement between the digital surface model derived from the aerial photographs and the geophysical prospection data. However, many structures could only be detected by one method, underlining the benefits of a complementary archaeological prospection approach using multiple methods. This article presents the results of the extensive surveys and their comprehensive integrative interpretation, discussing Bassianae's ground plan and urban infrastructure. Starting with an overview of this Roman town's research history, we present the details of the triple prospection approach, followed by the processing, integrative analysis, and interpretation of the acquired data sets. Finally, this newly gained information is contrasted with a plan of Roman Bassianae compiled in 1935.


2021 ◽  
Author(s):  
A. Sendrós ◽  
A. Casas ◽  
C. Abancó ◽  
L. Rivero ◽  
R. Garcia-Artigas ◽  
...  

2015 ◽  
Vol 19 (3) ◽  
pp. 1125-1139 ◽  
Author(s):  
P. Klenk ◽  
S. Jaumann ◽  
K. Roth

Abstract. High-resolution time-lapse ground-penetrating radar (GPR) observations of advancing and retreating water tables can yield a wealth of information about near-surface water content dynamics. In this study, we present and analyze a series of imbibition, drainage and infiltration experiments that have been carried out at our artificial ASSESS test site and observed with surface-based GPR. The test site features a complicated but known subsurface architecture constructed with three different kinds of sand. It allows the study of soil water dynamics with GPR under a wide range of different conditions. Here, we assess in particular (i) the feasibility of monitoring the dynamic shape of the capillary fringe reflection and (ii) the relative precision of monitoring soil water dynamics averaged over the whole vertical extent by evaluating the bottom reflection. The phenomenology of the GPR response of a dynamically changing capillary fringe is developed from a soil physical point of view. We then explain experimentally observed phenomena based on numerical simulations of both the water content dynamics and the expected GPR response.


2019 ◽  
Vol 17 (3) ◽  
pp. 291-298
Author(s):  
Niklas Allroggen ◽  
Adam D. Booth ◽  
Sandra E. Baker ◽  
Stephen A. Ellwood ◽  
Jens Tronicke

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