scholarly journals Seismic noise-based methods for soft-rock landslide characterization

2007 ◽  
Vol 178 (2) ◽  
pp. 137-148 ◽  
Author(s):  
Ombeline Méric ◽  
Stéphane Garambois ◽  
Jean-Philippe Malet ◽  
Héloïse Cadet ◽  
Philippe Guéguen ◽  
...  
Keyword(s):  
Seismic Noise ◽  
Slip Surface ◽  
Geophysical Methods ◽  
Soft Rock ◽  
Hazard Mapping ◽  
S Wave ◽  
Seismic Profiles ◽  
Electrical Tomography ◽  
Slip Surfaces ◽  
Set Up

Abstract In order to better understand the mechanics and dynamic of landslides, it is of primary interest to image correctly their internal structure and their slip surface. Several active geophysical methods are able to provide the geometry of a given landslide, but were rarely applied in 3 dimensions in the past. The main disadvantages of methods like seismic reflection and electrical tomography are that there are heavy to set up and/or to process, and they consequently are expensive and time consuming. Moreover, in the particular case of soft-rock landslides, their respective sensitivity and resolution are not always adequate to locate the potential slip surfaces. Passive methods may represent an interesting alternative particularly for landslides difficult to access, as they require lighter instrumentation and easier processing tools. Among them, the seismic noise based methods have shown increasing applications and developments, in particular for seismic hazard mapping in urban environment. In this paper, we present seismic noise investigations carried out on two different sites, the “Super Sauze” mudslide and the “Saint Guillaume” translational clayey landslide (France), where independent measurements (geotechnical and geophysical tests) were performed earlier. Our investigations were composed of electrical tomography profiles, seismic profiles for surface-wave inversions, H/V measurements, which are fast and easy to perform in the field, in order to image shear wave contrasts (slip surfaces), and seismic noise array method, which is heavier to apply and interpret, but provides (S)-waves velocity profile versus depth. For both sites, landslide bodies are characterized by lower S wave velocity (Vs < 300 m.s−1) and lower resistivity (ρ < 60 Ohm.m) than in the stable part (Vs > 550 m.s−1; ρ > 150 ohm.m). Their thickness vary from a few m to 50 m. Comparison between geophysical investigations and geotechnical data proved the applicability of such passive methods in 3D complex structures, with however some limitations.

scholarly journals Landslide geometry and activity in Villa de la Independencia (Bolivia) revealed by InSAR and seismic noise measurements

Landslides ◽  
2021 ◽  
Author(s):  
Chuang Song ◽  
Chen Yu ◽  
Zhenhong Li ◽  
Veronica Pazzi ◽  
Matteo Del Soldato ◽  
...  
Keyword(s):  
Time Series ◽  
Seismic Noise ◽  
Slip Surface ◽  
Inversion Method ◽  
Subsurface Structures ◽  
Slip Surfaces ◽  
Landslide Volume ◽  
Noise Measurements ◽  
Landslide Body

AbstractInterferometric Synthetic Aperture Radar (InSAR) enables detailed investigation of surface landslide movements, but it cannot provide information about subsurface structures. In this work, InSAR measurements were integrated with seismic noise in situ measurements to analyse both the surface and subsurface characteristics of a complex slow-moving landslide exhibiting multiple failure surfaces. The landslide body involves a town of around 6000 inhabitants, Villa de la Independencia (Bolivia), where extensive damages to buildings have been observed. To investigate the spatial-temporal characteristics of the landslide motion, Sentinel-1 displacement time series from October 2014 to December 2019 were produced. A new geometric inversion method is proposed to determine the best-fit sliding direction and inclination of the landslide. Our results indicate that the landslide is featured by a compound movement where three different blocks slide. This is further evidenced by seismic noise measurements which identified that the different dynamic characteristics of the three sub-blocks were possibly due to the different properties of shallow and deep slip surfaces. Determination of the slip surface depths allows for estimating the overall landslide volume (9.18 · 107 m3). Furthermore, Sentinel-1 time series show that the landslide movements manifest substantial accelerations in early 2018 and 2019, coinciding with increased precipitations in the late rainy season which are identified as the most likely triggers of the observed accelerations. This study showcases  the potential of integrating InSAR and seismic noise techniques to understand the landslide mechanism from ground to subsurface.

Application of passive and active seismic methods to subsurface investigation of Just-Tegoborze landslide (Outer Carpathians, Poland)

2020 ◽  
Author(s):  
Paulina Harba ◽  
Krzysztof Krawiec
Keyword(s):  
Wave Velocity ◽  
Seismic Noise ◽  
Slip Surface ◽  
Seismic Refraction ◽  
Seismic Interferometry ◽  
Geological Medium ◽  
S Wave ◽  
Passive Seismic ◽  
Outer Carpathians ◽  
Velocity Changes

<p>The study presents the results of seismic measurements on the Just-Tegoborze landslide located in Outer Carpathians in the southern region of Poland. The aim of the study was to investigate the landslide geological subsurface and define S-wave velocity changes within geological medium using passive seismic interferometry (SI) and active multichannel analysis of surface waves (MASW). Additionally, seismic refraction and numerical slip surface calculations were carried out in order to combine the results.</p><p>Measurements of SI were conducted based on local high-frequency seismic noise generated by heavy vehicles passing state road which intersects Just-Tegoborze landslide. Seismic noise registration was made using three-component broadband seismometers installed along a seismic profile. Measurements were repeated in a few series in different season and hydration conditions.</p><p>Seismic sections show different velocity layers within the landslide medium. Comparing them with geological cross-section of the studied area, we can distinguish the main lithological boundaries. First near-surface seismic layers may correspond to clayey colluvium and clayey-rock colluvium. The deepest seismic layer probably correlates to less weathered flysch bedrock made of shales and sandstones. It can be identified as the main slip surface of the studied landslide.</p><p>S-wave velocities within seismic profiles significantly varies between each measurement series of SI. It can be observed a decrease of S-wave velocity in March and July which is connected to seasonal weather and hydration conditions. Strong increase of hydration during melting snow cover in March and after heavy rainfalls in July resulted in loss of rigidity what presumably led to drop of S-wave velocity. Changes in hydration could also cause the variation of the course of the less weathered flysch bedrock boundary.</p><p>Presented results of passive seismic interferometry measurements show that study of seismic noise can be applicable to subsurface identification of an active landslide. The example of Just-Tegoborze site indicates that based on seismic interferometry it is possible to observe changes in elastic properties of geological medium. It is worth to underline that SI and MASW complement each other in retrieving the information of Rayleigh surface wave. Combining the results with seismic refraction and numerical calculations allows to better image the landslide geological subsurface. Such observations may be helpful in assessing landslide threat.</p>

Application of geophysical methods for the investigation of the large gravitational mass movement of Séchilienne, France

2005 ◽  
Vol 42 (4) ◽  
pp. 1105-1115 ◽  
Author(s):  
O Meric ◽  
S Garambois ◽  
D Jongmans ◽  
M Wathelet ◽  
J L Chatelain ◽  
...  
Keyword(s):  
Rock Mass ◽  
Mass Movement ◽  
Seismic Refraction ◽  
Geophysical Methods ◽  
Time Lapse ◽  
Gravitational Mass ◽  
Electrical Tomography ◽  
Refraction Tomography ◽  
Geophysical Surveys ◽  
Geophysical Techniques

Several geophysical techniques (electromagnetic profiling, electrical tomography, seismic refraction tomography, and spontaneous potential and seismic noise measurement) were applied in the investigation of the large gravitational mass movement of Séchilienne. France. The aim of this study was to test the ability of these methods to characterize and delineate the rock mass affected by this complex movement in mica schists, whose lateral and vertical limits are still uncertain. A major observation of this study is that all the zones strongly deformed (previously and at present) by the movement are characterized by high electrical resistivity values (>3 kΩ·m), in contrast to the undisturbed mass, which exhibits resistivity values between a few hundred and 1 kΩ·m. As shown by the surface observations and the seismic results, this resistivity increase is due to a high degree of fracturing associated with the creation of air-filled voids inside the mass. Other geophysical techniques were tested along a horizontal transect through the movement, and an outstanding coherency appeared between the geophysical anomalies and the displacement rate curve. These preliminary results illustrate the benefits of combined geophysical techniques for characterizing the rock mass involved in the movement. Results also suggest that monitoring the evolution of the rock mass movement with time-lapse geophysical surveys could be beneficial.Key words: gravitational movement, geophysical methods, Séchilienne.

The use of geophysical prospecting for imaging active faults in the Roer Graben, Belgium

Geophysics ◽  
2001 ◽  
Vol 66 (1) ◽  
pp. 78-89 ◽  
Author(s):  
Donat Demanet ◽  
François Renardy ◽  
Kris Vanneste ◽  
Denis Jongmans ◽  
Thierry Camelbeeck ◽  
...  
Keyword(s):  
High Resolution ◽  
Physical Properties ◽  
Fault Zone ◽  
Geophysical Methods ◽  
Depth Range ◽  
Electrical Tomography ◽  
Reflection Seismic ◽  
Refraction Seismic ◽  
Geophysical Surveys ◽  
Geophysical Techniques

As part of a paleoseismological investigation along the Bree fault scarp (western border of the Roer Graben), various geophysical methods [electrical profiling, electromagnetic (EM) profiling, refraction seismic tests, electrical tomography, ground‐penetrating radar (GPR), and high‐resolution reflection seismic profiles] were used to locate and image an active fault zone in a depth range between a few decimeters to a few tens of meters. These geophysical investigations, in parallel with geomorphological and geological analyses, helped in the decision to locate trench excavations exposing the fault surfaces. The results could then be checked with the observations in four trenches excavated across the scarp. Geophysical methods pointed out anomalies at all sites of the fault position. The contrast of physical properties (electrical resistivity and permittivity, seismic velocity) observed between the two fault blocks is a result of a differences in the lithology of the juxtaposed soil layers and of a change in the water table depth across the fault. Extremely fast techniques like electrical and EM profiling or seismic refraction profiles localized the fault position within an accuracy of a few meters. In a second step, more detailed methods (electrical tomography and GPR) more precisely imaged the fault zone and revealed some structures that were observed in the trenches. Finally, one high‐resolution reflection seismic profile imaged the displacement of the fault at depths as large as 120 m and filled the gap between classical seismic reflection profiles and the shallow geophysical techniques. Like all geophysical surveys, the quality of the data is strongly dependent on the geologic environment and on the contrast of the physical properties between the juxtaposed formations. The combined use of various geophysical techniques is thus recommended for fault mapping, particularly for a preliminary investigation when the geological context is poorly defined.

Convergence aspect of limit equilibrium methods for slopes

1990 ◽  
Vol 27 (1) ◽  
pp. 145-151 ◽  
Author(s):  
R. N. Chowdhury ◽  
S. Zhang
Keyword(s):  
Factor Of Safety ◽  
Slip Surface ◽  
Limit Equilibrium ◽  
Solution Process ◽  
Iterative Solution ◽  
Friction Angle ◽  
Equilibrium Analysis ◽  
Negative Slope ◽  
Slip Surfaces ◽  
Geological Discontinuity

This note is concerned with the multiplicity of solutions for the factor of safety that may be obtained on the basis of the method of slices. Discontinuities in the function for the factor of safety are discussed and the reasons for false convergence in any iterative solution process are explored, with particular reference to the well-known Bishop simplified method (circular slip surfaces) and Janbu simplified or generalized method (slip surfaces of arbitrary shape). The note emphasizes that both the solution method and the method of searching for the critical slip surface must be considered in assessing the potential for numerical difficulties and false convergence. Direct search methods for optimization (e.g., the simplex reflection method) appear to be superior to the grid search or repeated trial methods in this respect. To avoid false convergence, the initially assumed value of factor of safety F0 should be greater than β1(=−tan α1 tan [Formula: see text]) where α1 and [Formula: see text] are respectively the base inclination and internal friction angle of the first slice near the toe of a slope, the slice with the largest negative reverse inclination. A value of F0 = 1 + β1, is recommended on the basis of experience. If there is no slice with a negative slope for any of the slip surfaces generated in the automatic, search process, then any positive value of F0 will lead to true convergence for F. It is necessary to emphasize that no slip surface needs to be rejected for computational reasons except for Sarma's methods and similarly no artificial changes need to be made to the value of [Formula: see text] except for Sarma's methods. Key words: slope stability, convergence, limit equilibrium, analysis, optimization, slip surfaces, geological discontinuity, simplex reflection technique.

Detecting Underground Mines by Seismic Noise Autocorrelation and Geophysical Methods

2021 ◽  
Author(s):  
Martín Cárdenas-Soto ◽  
Jesús Sánchez-Gónzalez ◽  
José Martínez-González ◽  
Gerardo CIFUENTES-NAVA ◽  
David Zenil
Keyword(s):  
Seismic Noise ◽  
Geophysical Methods ◽  
Underground Mines

scholarly journals Formation, breaching and flood consequences of a landslide dam near Bujumbura, Burundi

2018 ◽  
Vol 18 (7) ◽  
pp. 1867-1890 ◽  
Author(s):  
Léonidas Nibigira ◽  
Hans-Balder Havenith ◽  
Pierre Archambeau ◽  
Benjamin Dewals
Keyword(s):  
Distinct Element ◽  
Mass Movement ◽  
Geophysical Methods ◽  
Landslide Dam ◽  
Propagation Time ◽  
Universal Distinct Element Code ◽  
Landslide Process ◽  
Distinct Element Code ◽  
Set Up ◽  
Flood Intensity

Abstract. This paper investigates the possible formation of a landslide dam on the Kanyosha River near Bujumbura, the capital of Burundi, as well as the interplay between the breaching of this landslide dam and the flooding along the river. We present an end-to-end analysis, ranging from the origin of the landslide up to the computation of flood waves induced by the dam breaching. The study includes three main steps. First, the mass movement site was investigated with various geophysical methods that allowed us to build a general 3-D model and detailed 2-D sections of the landslide. Second, this model was used for dynamic landslide process modelling with the Universal Distinct Element Code. The results showed that a 15 m high landslide dam may form on the river. Finally, a 2-D hydraulic model was set up to find out the consequences of the breaching of the landslide dam on flooding along the river, especially in an urban area located downstream. Based on 2-D maps of maximum water depth, flow velocity and wave propagation time, the results highlight that neglecting the influence of such landslide dams leads to substantial underestimation of flood intensity in the downstream area.

scholarly journals Structural analysis of S-wave seismics around an urban sinkhole; evidence of enhanced subrosion in a strike-slip fault zone

2017 ◽  
Author(s):  
Sonja H. Wadas ◽  
David C. Tanner ◽  
Ulrich Polom ◽  
Charlotte M. Krawczyk
Keyword(s):  
Strike Slip ◽  
Strike Slip Fault ◽  
Key Factors ◽  
S Wave ◽  
Seismic Profiles ◽  
Reflection Seismic ◽  
Dextral Strike Slip Fault ◽  
Seismic Sections ◽  
The Town ◽  
Dextral Strike Slip

Abstract. In November 2010, a large sinkhole opened up in the urban area of Schmalkalden, Germany. To determine the key factors which benefited the development of this collapse structure and therefore the subrosion, we carried out several shear wave reflection seismic profiles around the sinkhole. In the seismic sections we see evidence of the Mesozoic tectonic movement, in the form of a NW–SE striking, dextral strike-slip fault, known as the Heßleser Fault, which faulted and fractured the subsurface below the town. The strike-slip faulting created a zone of small blocks (

SOME RECENT ADVANCES IN OFFSHORE REGIONAL RECONNAISSANCE GEOPHYSICAL SURVEY METHODS

1967 ◽  
Vol 7 (1) ◽  
pp. 40
Author(s):  
K. R. Vale
Keyword(s):  
Phase Measurement ◽  
Survey Methods ◽  
Geophysical Methods ◽  
Low Frequency ◽  
Mineral Resources ◽  
Simultaneous Recording ◽  
Navigation Systems ◽  
Local Networks ◽  
Set Up ◽  
Geophysical Survey Methods

Traditional geophysical methods in use offshore include the airborne magnetometer, underwater gravity meter, and seismic reflection with 24-channel recording and large explosive energy source. Navigation is by range-range and hyperbolic phase-comparison radio systems set up as local networks. Other methods now being used include towed magnetometer, surface gravity meter, and automatic continuous seismic profilers, and all three methods can be used for simultaneous recording from a single recording boat. Navigation systems not requiring local networks include satellite radio doppler, very low frequency phase measurement and sonar doppler devices. These may be used word-wide and 24 hours per day. A single recording boat may thus be virtually self-sufficient. The Bureau of Mineral Resources plans a survey for 1967 that will use a number of these geophysical methods and navigation aids.

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