24. Near-Surface Geophysics in Berlin: Combined Geophysical Methods to Detect Near-Surface Obstacles to Construction in the New Capital of Germany

2005 ◽  
pp. 627-634
Author(s):  
C. Gelbke ◽  
B. Lehmann ◽  
U. Swoboda ◽  
R. Elsen
Keyword(s):  
Geophysical Methods ◽  
Near Surface ◽  
Near Surface Geophysics

scholarly journals Subsurface characterization of a quick-clay vulnerable area using near-surface geophysics and hydrological modelling

Solid Earth ◽  
2019 ◽  
Vol 10 (5) ◽  
pp. 1685-1705
Author(s):  
Silvia Salas-Romero ◽  
Alireza Malehmir ◽  
Ian Snowball ◽  
Benoît Dessirier
Keyword(s):  
Large Scale ◽  
Geophysical Methods ◽  
Hydrological Modelling ◽  
P Wave ◽  
Coarse Grained ◽  
Near Surface ◽  
Reflection Seismic ◽  
Geotechnical Investigations ◽  
Quick Clay ◽  
Near Surface Geophysics

Abstract. Quick-clay landslides are common geohazards in Nordic countries and Canada. The presence of potential quick clays is confirmed using geotechnical investigations, but near-surface geophysical methods, such as seismic and resistivity surveys, can also help identify coarse-grained materials associated with the development of quick clays. We present the results of reflection seismic investigations on land and in part of the Göta River in Sweden, along which many quick-clay landslide scars exist. This is the first time that such a large-scale reflection seismic investigation has been carried out to study the subsurface structures associated with quick-clay landslides. The results also show a reasonable correlation with radio magnetotelluric and travel-time tomography models of the subsurface. Other ground geophysical data, such as high magnetic values, suggest a positive correlation with an increased thickness of the coarse-grained layer and shallower depths to the top of the bedrock and the top of the coarse-grained layer. The morphology of the river bottom and riverbanks, e.g. subaquatic landslide deposits, is shown by side-scan sonar and bathymetric data. Undulating bedrock, covered by subhorizontal sedimentary glacial and postglacial deposits, is clearly revealed. An extensive coarse-grained layer (P-wave velocity mostly between 1500 and 2500 m s−1 and resistivity from approximately 80 to 100 Ωm) exists within the sediments and is interpreted and modelled in a regional context. Several fracture zones are identified within the bedrock. Hydrological modelling of the coarse-grained layer confirms its potential for transporting fresh water infiltrated in fractures and nearby outcrops located in the central part of the study area. The modelled groundwater flow in this layer promotes the leaching of marine salts from the overlying clays by seasonal inflow–outflow cycles and/or diffusion, which contributes to the formation of potential quick clays.

scholarly journals First geophysical results in the Archeological sites of Θούρια (Péloponnèse, Hellas) and Sibari-Thurii (southern Italy)

2018 ◽  
Vol 40 (3) ◽  
pp. 1080
Author(s):  
B. Di Fiore ◽  
D. Chianese ◽  
A. Loperte ◽  
G. Conte ◽  
A. Dibenedetto ◽  
...  
Keyword(s):  
High Resolution ◽  
Information Quality ◽  
Southern Italy ◽  
Magnetic Measurements ◽  
Early Stage ◽  
Geophysical Methods ◽  
Magnetic Data ◽  
Near Surface ◽  
Data Inversion ◽  
Near Surface Geophysics

High resolution techniques for data acquisition and processing procedures are increasingly applied in near-surface geophysics for archaeology. In this paper we present the preliminary results of two geophysical measurements campaigns aimed to the investigation of buried remains in the archaeological sites of Θουρία (Péloponnèse, Hellas) and Sibari (Southern Italy). In the first field survey the geophysical approach involved the integrated application of the geoelectrical and magnetic methods and an innovative tomographic analysis for the inversion of both resistivity and magnetic data. In the second case, we carried out high resolution magnetic measurements, interpreted by means of the use of an appropriate filtering procedure. The applied data inversion allows us to provide reliable space patterns of the most probable specific target boundaries, improving the information quality of geophysical methods. The results obtained at this early stage of data processing confirm some archaeological hypothesis about the investigated areas and confirm that the use of integrated geophysical methods allows the archaeologists to reduce the time and the costs of their surveys.

Introduction to this special section: Near-surface geophysics

2019 ◽  
Vol 38 (6) ◽  
pp. 434-434
Author(s):  
Adam Mangel ◽  
Steve Sloan
Keyword(s):  
Special Section ◽  
Geophysical Methods ◽  
National Research Council ◽  
Natural World ◽  
Food Sources ◽  
Natural Ecosystems ◽  
Near Surface ◽  
The Past ◽  
The Earth ◽  
Near Surface Geophysics

The near surface of the earth, a.k.a. the critical zone (National Research Council, 2001), is defined as the outer 50–100 m of the planet, which contains biota, bedrock, soil, water, and gasses. As humans, we rely on this layer for many functions including storage of water resources, housing of our infrastructure, storage of our wastes, and cultivation of our food sources. Several natural ecosystems are also dependent on this layer of our planet, which in turn provide us with ecosystem services. The historic and lasting importance of this layer to our environment emphasizes the value in understanding major environmental fluxes, impact of human activities, and the interface between the natural world and our infrastructure. Application of geophysical methods in this field has increased steadily over the past 15 years and continues to grow, especially as the human impact on the globe continues to increase.

Advancing process-based watershed hydrological research using near-surface geophysics: a vision for, and review of, electrical and magnetic geophysical methods

2008 ◽  
Vol 22 (18) ◽  
pp. 3604-3635 ◽  
Author(s):  
D. A. Robinson ◽  
A. Binley ◽  
N. Crook ◽  
F. D. Day-Lewis ◽  
T. P. A. Ferré ◽  
...  
Keyword(s):  
Geophysical Methods ◽  
Near Surface ◽  
Near Surface Geophysics

4D-Quantification of alpine permafrost degradation in a bedrock ridge using multiple inversion schemes and deformation measurements

2021 ◽  
Author(s):  
Maike Offer ◽  
Riccardo Scandroglio ◽  
Daniel Draebing ◽  
Michael Krautblatter
Keyword(s):  
Climate Change ◽  
Mechanical Stability ◽  
Regularization Parameter ◽  
Time Lapse ◽  
Permafrost Degradation ◽  
Thermal Dynamics ◽  
Near Surface ◽  
Data Error ◽  
Near Surface Geophysics ◽  
Thawing Rate

<p>Warming of permafrost in steep rock walls decreases their mechanical stability and could triggers rockfalls and rockslides. However, the direct link between climate change and permafrost degradation is seldom quantified with precise monitoring techniques and long-term time series. Where boreholes are not possible, laboratory-calibrated Electrical Resistivity Tomography (ERT) is presumably the most accurate quantitative permafrost monitoring technique providing a sensitive record for frozen vs. unfrozen bedrock. Recently, 4D inversions allow also quantification of frozen bedrock extension and of its changes with time (Scandroglio et al., in review).</p><p>In this study we (i) evaluate the influence of the inversion parameters on the volumes and (ii) connect the volumetric changes with measured mechanical consequences.</p><p>The ERT time-serie was recorded between 2006 and 2019 in steep bedrock at the permafrost affected Steintälli Ridge (3100 m asl). Accurately positioned 205 drilled-in steel electrodes in 5 parallel lines across the rock ridge have been repeatedly measured with similar hardware and are compared to laboratory temperature-resistivity (T–ρ) calibration of water-saturated samples from the field. Inversions were conducted using the open-source software BERT for the first time with the aim of estimating permafrost volumetric changes over a decade.</p><p>(i) Here we present a sensitivity analysis of the outcomes by testing various plausible inversion set-ups. Results are computed with different input data filters, data error model, regularization parameter (λ), model roughness reweighting and time-lapse constraints. The model with the largest permafrost degradation was obtained without any time-lapse constraints, whereas constraining each model with the prior measurement results in the smallest degradation. Important changes are also connected to the data error estimation, while other setting seems to have less influence on the frozen volume. All inversions confirmed a drastic permafrost degradation in the last 13 years with an average reduction of 3.900±600 m<sup>3</sup> (60±10% of the starting volume), well in agreement with the measured air temperatures increase.</p><p>(ii) Average bedrock thawing rate of ~300 m<sup>3</sup>/a is expected to significantly influence the stability of the ridge. Resistivity changes are especially evident on the south-west exposed side and in the core of the ridge and are here connected to deformations measured with tape extensometer, in order to precisely estimate the mechanical consequences of bedrock warming.</p><p>In summary, the strong degradation of permafrost in the last decade it’s here confirmed since inversion settings only have minor influence on volume quantification. Internal thermal dynamics need correlation with measured external deformation for a correct interpretation of stability consequences. These results are a fundamental benchmark for evaluating mountain permafrost degradation in relation to climate change and demonstrate the key role of temperature-calibrated 4D ERT.</p><p> </p><p>Reference:</p><p>Scandroglio, R. et al. (in review) ‘4D-Quantification of alpine permafrost degradation in steep rock walls using a laboratory-calibrated ERT approach’, <em>Near Surface Geophysics</em>.</p>

scholarly journals Klotzsche Receives 2020 Near-Surface Geophysics Early Career Achievement Award

Eos ◽  
2021 ◽  
Vol 102 ◽  
Author(s):  
Keyword(s):  
Early Career ◽  
Fall Meeting ◽  
Near Surface ◽  
Career Achievement ◽  
Achievement Award ◽  
Early Career Researcher ◽  
Near Surface Geophysics

Anja Klotzsche received the inaugural Near-Surface Geophysics Early Career Achievement Award at AGU’s virtual Fall Meeting 2020. The award is given in recognition of “significant contributions to the field of near-surface geophysics by an early-career researcher.”

Sign in / Sign up

Export Citation Format

Share Document