scholarly journals Seismic physics-based characterization of permafrost sites using surface waves

2021 ◽  
Author(s):  
Hongwei Liu ◽  
Pooneh Maghoul ◽  
Ahmed Shalaby
Keyword(s):  
Mechanical Properties ◽  
Surface Wave ◽  
Surface Waves ◽  
Wave Velocity ◽  
Rayleigh Waves ◽  
Climate Model ◽  
Physical And Mechanical Properties ◽  
Unfrozen Water ◽  
Soil Layers ◽  
Unfrozen Water Content

Abstract. The adverse effects of climate warming on the built environment in (sub)arctic regions are unprecedented and accelerating. Planning and design of climate-resilient northern infrastructure as well as predicting deterioration of permafrost from climate model simulations require characterizing permafrost sites accurately and efficiently. Here, we propose a novel algorithm for analysis of surface waves to quantitatively estimate the physical and mechanical properties of a permafrost site. We show the existence of two types of Rayleigh waves (R1 and R2; R1 travels relatively faster than R2). The R2 wave velocity is highly sensitive to the physical properties (e.g., unfrozen water content, ice content, and porosity) of permafrost or soil layers while it is less sensitive to their mechanical properties (e.g., shear modulus and bulk modulus). The R1 wave velocity, on the other hand, depends strongly on the soil type and mechanical properties of permafrost or soil layers. In-situ surface wave measurements revealed the experimental dispersion relations of both types of Rayleigh waves from which relevant properties of a permafrost site can be derived by means of our proposed hybrid inverse and multi-phase poromechanical approach. Our study demonstrates the potential of surface wave techniques coupled with our proposed data-processing algorithm to characterize a permafrost site more accurately. Our proposed technique can be used in early detection and warning systems to monitor infrastructure impacted by permafrost-related geohazards, and to detect the presence of layers vulnerable to permafrost carbon feedback and emission of greenhouse gases into the atmosphere.

Retrieval of shallow S-wave profiles from seismic reflection surveying and traffic-induced noise

Geophysics ◽  
2020 ◽  
Vol 85 (6) ◽  
pp. EN105-EN117
Author(s):  
Kai Zhang ◽  
Hongyi Li ◽  
Xiaojiang Wang ◽  
Kai Wang
Keyword(s):  
Surface Wave ◽  
Surface Waves ◽  
Wave Velocity ◽  
Rayleigh Waves ◽  
Seismic Reflection ◽  
Seismic Energy ◽  
Dispersion Curves ◽  
S Wave ◽  
Near Surface ◽  
Wave Velocities

In urban subsurface exploration, seismic surveys are mostly conducted along roads where seismic vibrators can be extensively used to generate strong seismic energy due to economic and environmental constraints. Generally, Rayleigh waves also are excited by the compressional wave profiling process. Shear-wave (S-wave) velocities can be inferred using Rayleigh waves to complement near-surface characterization. Most vibrators cannot excite seismic energy at lower frequencies (<5 Hz) to map greater depths during surface-wave analysis in areas with low S-wave velocities, but low-frequency surface waves ([Formula: see text]) can be extracted from traffic-induced noise, which can be easily obtained at marginal additional cost. We have implemented synthetic tests to evaluate the velocity deviation caused by offline sources, finding a reasonably small relative bias of surface-wave dispersion curves due to vehicle sources on roads. Using a 2D reflection survey and traffic-induced noise from the central North China Plain, we apply seismic interferometry to a series of 10.0 s segments of passive data. Then, each segment is selectively stacked on the acausal-to-causal ratio of the mean signal-to-noise ratio to generate virtual shot gathers with better dispersion energy images. We next use the dispersion curves derived by combining controlled source surveying with vehicle noise to retrieve the shallow S-wave velocity structure. A maximum exploration depth of 90 m is achieved, and the inverted S-wave profile and interval S-wave velocity model obtained from reflection processing appear consistent. The data set demonstrates that using surface waves derived from seismic reflection surveying and traffic-induced noise provides an efficient supplementary technique for delineating shallow structures in areas featuring thick Quaternary overburden. Additionally, the field test indicates that traffic noise can be created using vehicles or vibrators to capture surface waves within a reliable frequency band of 2–25 Hz if no vehicles are moving along the survey line.

scholarly journals Characteristics of the horizontal component of Rayleigh waves in multimode analysis of surface waves

Geophysics ◽  
2015 ◽  
Vol 80 (1) ◽  
pp. EN1-EN11 ◽  
Author(s):  
Tatsunori Ikeda ◽  
Toshifumi Matsuoka ◽  
Takeshi Tsuji ◽  
Toru Nakayama
Keyword(s):  
Surface Waves ◽  
Wave Velocity ◽  
Rayleigh Waves ◽  
Field Data ◽  
Vertical Component ◽  
Dispersion Curves ◽  
Horizontal Component ◽  
S Wave ◽  
Higher Modes ◽  
Explosive Source

In surface-wave analysis, S-wave velocity estimations can be improved by the use of higher modes of the surface waves. The vertical component of P-SV waves is commonly used to estimate multimode Rayleigh waves, although Rayleigh waves are also included in horizontal components of P-SV waves. To demonstrate the advantages of using the horizontal components of multimode Rayleigh waves, we investigated the characteristics of the horizontal and vertical components of Rayleigh waves. We conducted numerical modeling and field data analyses rather than a theoretical study for both components of Rayleigh waves. As a result of a simulation study, we found that the estimated higher modes have larger relative amplitudes in the vertical and horizontal components as the source depth increases. In particular, higher-order modes were observed in the horizontal component data for an explosive source located at a greater depth. Similar phenomena were observed in the field data acquired by using a dynamite source at 15-m depth. Sensitivity analyses of dispersion curves to S-wave velocity changes revealed that dispersion curves additionally estimated from the horizontal components can potentially improve S-wave velocity estimations. These results revealed that when the explosive source was buried at a greater depth, the horizontal components can complement Rayleigh waves estimated from the vertical components. Therefore, the combined use of the horizontal component data with the vertical component data would contribute to improving S-wave velocity estimations, especially in the case of buried explosive source signal.

Surface-wave dispersion analysis in Mexico City

1995 ◽  
Vol 85 (4) ◽  
pp. 1116-1126
Author(s):  
Francisco J. Chávez-García ◽  
Jaime Ramos-Martínez ◽  
Evangelina Romero-Jiménez
Keyword(s):  
Surface Wave ◽  
Surface Waves ◽  
Ground Motion ◽  
Mexico City ◽  
Rayleigh Waves ◽  
Strong Motion ◽  
Clay Layer ◽  
Period Range ◽  
Wave Trains ◽  
Refraction Data

Abstract In this article, we present an observational investigation of ground motion at Mexico City focused on surface waves. Our purpose is 2-fold; first, to understand incident ground motion during the great Michoacán earthquake of 19 September 1985, and second, to characterize surface waves propagating in the lake-bed zone. To this end we analyze the strong-motion records obtained at Mexico City for the large (MS = 8.1) earthquake of 19 September 1985. It is shown that, in the low-frequency range, we observe the Rayleigh fundamental mode in both the vertical and the radial components, and the Love fundamental mode in the transverse component at all the strong-motion stations. The vertical component also shows the first higher mode of Rayleigh waves. We use a very broadband record obtained at station CU for the smaller (MS = 6.7) earthquake of 14 May 1993 to verify that the dispersion computed from the model of Campillo et al. (1989) represents well the average surface-wave propagation between the coast and Mexico City in the 7- to 10-sec period range. We use this result to assign absolute times to the strong-motion records of the Michoacán event. This allowed us to identify additional wave trains that propagate laterally in directions other than great circle in the 3- to 5-sec period range. These wave trains are identified as Love waves. In a second analysis, we study a set of refraction data obtained during a small-scale (250 m) experiment on the virgin clay of the lake-bed zone. Phase-velocity dispersion curves for several modes of Rayleigh waves are identified in the refraction data and inverted to obtain an S-wave velocity profile. This profile is used as the uppermost layering in a 2D model of Mexico City valley. The results of numerical simulation show that surface waves generated by lateral finiteness of the clay layer suffer large dispersion and attenuation. We conclude that surface waves generated by the lateral heterogeneity of the upper-most stratigraphy very significantly affect ground motion near the edge of the valley, but their importance is negligible for distances larger than 1.5 km from the edge. Thus, locally generated surface waves propagating through the clay layer cannot explain late arrivals observed for the 1985 event. We suggest that the long duration of strong motion is due to the interaction between lateral propagation of waves guided by deep layers (1 to 4 km) and the surficial clay layer. This interaction is possible by the coincidence of the dominant frequency of the uppermost layers and the frequency of the deeply guided waves.

Crustal structure of the Iceland region from dispersion of surface waves

1962 ◽  
Vol 52 (2) ◽  
pp. 359-388
Author(s):  
Eysteinn Tryggvason
Keyword(s):  
Surface Layer ◽  
Surface Wave ◽  
Surface Waves ◽  
Wave Velocity ◽  
Crustal Structure ◽  
Wave Dispersion ◽  
P Wave ◽  
S Wave ◽  
Surface Wave Dispersion ◽  
Mid Atlantic Ridge

ABSTRACT A number of Icelandic records of earthquakes originating in the Mid-Atlantic Seismic Belt between 52° and 70° N. lat. have been investigated. The surface waves on these records are chiefly in the period interval 3–10 sec, and are first mode Love-waves and Rayleigh-waves. The surface wave dispersion can be explained by a three-layered crustal structure as follows. A surface layer of S-wave velocity about 2.7 km/sec covering the whole region studied, a second layer of S-wave velocity about 3.6 km/sec covering Iceland and extending several hundred kilometers off the coasts and a third layer of S-wave velocity about 4.3 km/sec and P-wave velocity about 7.4 km/sec underlying the whole region. The thickness of the surface layer appears to be about 4 km on the Mid-Atlantic Ridge south of Iceland and in western Iceland, 3 km in central Iceland and 7 km northwest of Iceland. The second layer is apparently of similar thickness than the surface layer, while the third layer is thick; and the surface wave dispersion does not indicate any layer of higher wave velocity. This 7.4-layer is supposed to belong to the mantle, although its wave velocity is significantly lower than usually found in the upper mantle

Multichannel analysis of surface waves

Geophysics ◽  
1999 ◽  
Vol 64 (3) ◽  
pp. 800-808 ◽  
Author(s):  
Choon B. Park ◽  
Richard D. Miller ◽  
Jianghai Xia
Keyword(s):  
Surface Wave ◽  
Surface Waves ◽  
Dispersion Curve ◽  
Shear Wave ◽  
Wave Velocity ◽  
Shear Wave Velocity ◽  
Frequency Component ◽  
Multichannel Recording ◽  
Phase Velocities ◽  
Ground Roll

The frequency‐dependent properties of Rayleigh‐type surface waves can be utilized for imaging and characterizing the shallow subsurface. Most surface‐wave analysis relies on the accurate calculation of phase velocities for the horizontally traveling fundamental‐mode Rayleigh wave acquired by stepping out a pair of receivers at intervals based on calculated ground roll wavelengths. Interference by coherent source‐generated noise inhibits the reliability of shear‐wave velocities determined through inversion of the whole wave field. Among these nonplanar, nonfundamental‐mode Rayleigh waves (noise) are body waves, scattered and nonsource‐generated surface waves, and higher‐mode surface waves. The degree to which each of these types of noise contaminates the dispersion curve and, ultimately, the inverted shear‐wave velocity profile is dependent on frequency as well as distance from the source. Multichannel recording permits effective identification and isolation of noise according to distinctive trace‐to‐trace coherency in arrival time and amplitude. An added advantage is the speed and redundancy of the measurement process. Decomposition of a multichannel record into a time variable‐frequency format, similar to an uncorrelated Vibroseis record, permits analysis and display of each frequency component in a unique and continuous format. Coherent noise contamination can then be examined and its effects appraised in both frequency and offset space. Separation of frequency components permits real‐time maximization of the S/N ratio during acquisition and subsequent processing steps. Linear separation of each ground roll frequency component allows calculation of phase velocities by simply measuring the linear slope of each frequency component. Breaks in coherent surface‐wave arrivals, observable on the decomposed record, can be compensated for during acquisition and processing. Multichannel recording permits single‐measurement surveying of a broad depth range, high levels of redundancy with a single field configuration, and the ability to adjust the offset, effectively reducing random or nonlinear noise introduced during recording. A multichannel shot gather decomposed into a swept‐frequency record allows the fast generation of an accurate dispersion curve. The accuracy of dispersion curves determined using this method is proven through field comparisons of the inverted shear‐wave velocity ([Formula: see text]) profile with a downhole [Formula: see text] profile.

A comprehensive comparison between the refraction microtremor and seismic interferometry methods for phase-velocity estimation

Geophysics ◽  
2017 ◽  
Vol 82 (6) ◽  
pp. EN99-EN108 ◽  
Author(s):  
Zongbo Xu ◽  
T. Dylan Mikesell ◽  
Jianghai Xia ◽  
Feng Cheng
Keyword(s):  
Surface Wave ◽  
Surface Waves ◽  
Wave Velocity ◽  
Velocity Estimation ◽  
Seismic Interferometry ◽  
S Wave ◽  
Noise Sources ◽  
Surface Wave Dispersion ◽  
Near Surface ◽  
Refraction Microtremor

Passive-source seismic-noise-based surface-wave methods are now routinely used to investigate the near-surface geology in urban environments. These methods estimate the S-wave velocity of the near surface, and two methods that use linear recording arrays are seismic interferometry (SI) and refraction microtremor (ReMi). These two methods process noise data differently and thus can yield different estimates of the surface-wave dispersion, the data used to estimate the S-wave velocity. We have systematically compared these two methods using synthetic data with different noise source distributions. We arrange sensors in a linear survey grid, which is conveniently used in urban investigations (e.g., along roads). We find that both methods fail to correctly determine the low-frequency dispersion characteristics when outline noise sources become stronger than inline noise sources. We also identify an artifact in the ReMi method and theoretically explain the origin of this artifact. We determine that SI combined with array-based analysis of surface waves is the more accurate method to estimate surface-wave phase velocities because SI separates surface waves propagating in different directions. Finally, we find a solution to eliminate the ReMi artifact that involves the combination of SI and the [Formula: see text]-[Formula: see text] transform, the array processing method that underlies the ReMi method.

scholarly journals Two-Dimensional Full-Waveform Joint Inversion of Surface Waves Using Phases and Z/H Ratios

2021 ◽  
Vol 11 (15) ◽  
pp. 6712
Author(s):  
Chao Zhang ◽  
Ting Lei ◽  
Yi Wang
Keyword(s):  
Surface Wave ◽  
Surface Waves ◽  
Wave Velocity ◽  
Joint Inversion ◽  
Waveform Inversion ◽  
Small Scale ◽  
Imaging Method ◽  
S Wave ◽  
Surface Wave Dispersion ◽  
Full Waveform

Surface-wave dispersion and the Z/H ratio are important parameters used to resolve the Earth’s structure, especially for S-wave velocity. Several previous studies have explored using joint inversion of these two datasets. However, all of these studies used a 1-D depth-sensitivity kernel, which lacks precision when the structure is laterally heterogeneous. Adjoint tomography (i.e., full-waveform inversion) is a state-of-the-art imaging method with a high resolution. It can obtain better-resolved lithospheric structures beyond the resolving ability of traditional ray-based travel-time tomography. In this study, we present a systematic investigation of the 2D sensitivities of the surface wave phase and Z/H ratio using the adjoint-state method. The forward-modeling experiments indicated that the 2D phase and Z/H ratio had different sensitivities to the S-wave velocity. Thus, a full-waveform joint-inversion scheme of surface waves with phases and a Z/H ratio was proposed to take advantage of their complementary sensitivities to the Earth’s structure. Both applications to synthetic data sets in large- and small-scale inversions demonstrated the advantage of the joint inversion over the individual inversions, allowing for the creation of a more unified S-wave velocity model. The proposed joint-inversion scheme offers a computationally efficient and inexpensive alternative to imaging fine-scale shallow structures beneath a 2D seismic array.

A surface wave particle motion discrimination process

1968 ◽  
Vol 58 (2) ◽  
pp. 629-637
Author(s):  
R. S. Simons
Keyword(s):  
Surface Wave ◽  
Surface Waves ◽  
Particle Motion ◽  
Seismic Data ◽  
Digital Computer ◽  
Rayleigh Waves ◽  
Motion Pattern ◽  
Signal To Noise ◽  
Long Period ◽  
Period Data

Abstract A digital computer process is described which examines the three-componen particle-motion pattern of seismic data as a function of frequency and uses this information to discriminate against all motion except surface waves arriving from some pre-assigned direction. Application of the process to long-period data has shown that it can substantially improve the signal-to-noise ratios of Love and Rayleigh waves from earthquakes and underground detonations.

The effect of oceanic sediments on surface-wave propagation

1975 ◽  
Vol 65 (6) ◽  
pp. 1531-1552
Author(s):  
Donald J. Weidner
Keyword(s):  
Surface Wave ◽  
Surface Waves ◽  
Rayleigh Waves ◽  
Propagation Path ◽  
Surface Wave Propagation ◽  
Oceanic Surface ◽  
Oceanic Sediments ◽  
Wave Phase Velocity ◽  
Short Period ◽  
Mid Atlantic Ridge

abstract Several characteristics of oceanic surface waves can be altered by the presence of low rigidity sediments along the propagation path. Love and Rayleigh waves from mid-Atlantic ridge earthquakes bear many effects of oceanic sediments. The general absence of these surface waves for periods shorter than about 15 sec can be attributed to either attenuation or scattering in thin sediments. Thin sediments also disperse short-period Love waves. Sediments whose thickness exceeds about 2 km are responsible for removing surface-wave energy with periods up to 40 sec. These sediments also alter the particle motion of Rayleigh waves and are responsible for a complicated dispersion relation. These thick sediments substantially reduce the surface-wave phase velocity at periods in excess of 100 sec.

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