Joint Inversion of Multimode Love Wave Dispersion Curves for Accurately Appraising of Shear Wave Velocity Reversal Profile

2010 ◽  
Author(s):  
La Hamimu ◽  
M. Nawawi M. Nordin ◽  
Jamhir Safani ◽  
A. K. Yahya ◽  
Shah Alam
Keyword(s):  
Shear Wave ◽  
Wave Velocity ◽  
Shear Wave Velocity ◽  
Love Wave ◽  
Joint Inversion ◽  
Wave Dispersion ◽  
Dispersion Curves ◽  
Velocity Reversal ◽  
Love Wave Dispersion

Crustal structure of the north Pacific from Love-wave dispersion

1959 ◽  
Vol 49 (4) ◽  
pp. 331-336
Author(s):  
John De Noyer
Keyword(s):  
Shear Wave ◽  
Wave Velocity ◽  
Shear Wave Velocity ◽  
Love Wave ◽  
Wave Dispersion ◽  
The North ◽  
Shear Wave Velocities ◽  
Crustal Model ◽  
Short Period ◽  
Love Wave Dispersion

Abstract Short-period Love wave dispersion from the Kurile Islands earthquake (June 22, 1952; O = 21b 41m 53s; φ = 46° N; λ = 153°.5 E) can be explained with a two-layer crustal model in which the upper 2 km. of material has a shear-wave velocity of 2.31 km/sec. The second layer has a thickness of 4 km. and a shear-wave velocity of 3.71 to 3.86 km/sec. Shear-wave velocities of 4.50 to 4.52 km/sec. are used for the material immediately below the crust. This crustal model is compared with structures obtained from short-period Love wave dispersion across other Pacific paths and with results of refraction studies.

The complementarity of H/V and dispersion curves

Geophysics ◽  
2016 ◽  
Vol 81 (6) ◽  
pp. T323-T338 ◽  
Author(s):  
Silvia Castellaro
Keyword(s):  
Surface Waves ◽  
Shear Wave ◽  
Wave Velocity ◽  
Shear Wave Velocity ◽  
Love Wave ◽  
Velocity Profiles ◽  
Dispersion Curves ◽  
Source Surface ◽  
Diagnostic Features ◽  
Single Station

Noninvasive geophysical techniques based on the dispersion of surface waves in layered media are commonly used approaches for measuring shear-wave velocity profiles of the subsoil. Acquiring surface waves is a simple task, but the interpretation of their dispersion curves poses a number of challenges. In an increasing number of cases, shear-wave velocity profiles are derived from the inversion of dispersion curves of surface waves and single-station passive horizontal-to-vertical (H/V) spectral ratios, mostly using a blind joint fit of the two sets of curves. Here we emphasize the benefits of carrying out H/V surveys prior to any array acquisition. We propose to start by collecting at least two H/V recordings at a site to verify the 1D plane-parallel soil condition, as this is essential in dispersion curve inversion/modeling. Then, we look for the diagnostic features of velocity inversions in the H/V curves: when they occur, the interpretation of dispersion curves is made difficult by mode splitting/superposition and Love wave arrays will not be effective. Then we inspect the shape of the H/V curves: flat curves acquired on rock usually imply poor dispersion curves. Large receiver spacings are recommended in the arrays and Love wave arrays will not be efficient. Flat curves on soft material sites represent gently increasing [Formula: see text] gradients and Rayleigh wave arrays should be preferred. H/V curves with high frequency peaks indicate shallow impedance contrasts: this makes Love wave arrays efficient for the soft layer characterization, but provide little information at depth. H/V curves with low frequency peaks indicate deep bedrock and their inversion can provide approximate [Formula: see text] profiles down to greater depths than from an array. Equipped with the information coming from accurate H/V observations, practitioners could make better-informed decisions about array acquisition geometries, source/surface wave types, and inversion strategies.

scholarly journals Shear-wave Velocity Structure of Greenland from Rayleigh-wave Analysis

2016 ◽  
Vol 20 (1) ◽  
pp. 1-11 ◽  
Author(s):  
V. Corchete
Keyword(s):  
Rayleigh Wave ◽  
Shear Wave ◽  
Wave Velocity ◽  
Shear Wave Velocity ◽  
Velocity Structure ◽  
Wave Dispersion ◽  
Dispersion Curves ◽  
Depth Range ◽  
Velocity Models ◽  
Rayleigh Wave Dispersion

<p>The elastic structure beneath Greenland is shown by means of S-velocity maps for depths ranging from zero to 350 km, determined by the regionalization and inversion of Rayleigh-wave dispersion. The traces of 50 earthquakes, occurring from 1990 to 2011, have been used to obtain Rayleigh-wave dispersion data. These earthquakes were registered by 21 seismic station located in Greenland and the surrounding area. The dispersion curves were obtained for periods between 5 and 200 s, by digital filtering with a combination of MFT (Multiple Filter Technique) and TVF (Time Variable Filtering). Later, all seismic events (and some stations) were grouped to obtain a dispersion curve for each source-station path. These dispersion curves were regionalized and inverted according to the generalized inversion theory, to obtain shear-wave velocity models for a rectangular grid of 16x20 points. The shear-velocity structure obtained through this procedure is shown in the S-velocity maps plotted for several depths. These results agree well with the geology and other geophysical results previously obtained. The obtained S-velocity models suggest the existence of lateral and vertical heterogeneity. The zones with consolidated and old structures present greater S-velocity values than the other zones, although this difference can be very little or negligible in some case. Nevertheless, in the depth range of 15 to 45 km, the different Moho depths present in the study area generate the principal variation of S-velocity. A similar behaviour is found for the depth range from 80 to 230 km, in which the lithosphere-asthenosphere boundary (LAB) generates the principal variations of S-velocity. Finally, the new and interesting feature obtained in this study: the definition of the base of the asthenosphere (for the whole study area and for depths ranging from 130 to 280 km, respectively) should be highlighted.</p><p> </p><p><strong>Estructura de velocidad de cizalla de Groenlandia obtenida de análisis de onda Rayleigh</strong></p><p><strong><br /></strong></p><p><strong>Resumen</strong></p><p>La estructura elástica bajo Groenlandia es mostrada por medio de mapas de velocidad de onda para profundidades variando desde cero a 350 km, determinada por la regionalización e inversión de la dispersión de onda Rayleigh. Las trazas de 50 terremotos, ocurridos desde 1990 hasta 2011, han sido usados para obtener datos de dispersión de onda Rayleigh. Estos terremotos fueron registrados por 21 estaciones sísmicas localizadas en Groenlandia y el área circundante. Las curvas de dispersión fueron obtenidas para periodos entre 5 y 200 s, por filtrado digital con una combinación de MFT (Técnica de Filtrado Múltiple) y TVF (Filtrado en Tiempo Variable). Después, todos los eventos sísmicos (y algunas estaciones) fueron agrupados para obtener una curva de dispersión para cada trayecto fuente-estación. Estas curvas de dispersión fueron regionalizadas e invertidas de acuerdo con la teoría de la inversión generalizada, para obtener modelos de velocidad de cizalla para una rejilla rectangular de 16x20 puntos. La estructura de velocidad de cizalla obtenida a través de este procedimiento es mostrada in los mapas de velocidad de onda S representados para varias profundidades. Estos resultados muestran buen acuerdo con la geología y con otros resultados geofísicos obtenidos previamente. Los modelos de velocidad de onda S obtenidos sugieren la existencia de heterogeneidad lateral y vertical. Las zonas con estructuras antiguas y consolidadas presentan mayores valores de velocidad de onda S que las otras zonas, aunque esta diferencia puede ser muy pequeña o despreciable en algún caso. No obstante, en el rango de profundidad de 15 a 45 km, las diferentes profundidades del Moho presentes en el área de estudio generan la principal variación de velocidad de onda S. Un comportamiento similar es encontrado para el rango de profundidad desde 80 a 230 km, en el cual la frontera litosfera-astenosfera (LAB) genera las principales variaciones de velocidad de onda S. Finalmente, debería ser destacada la nueva e interesante característica obtenida en este estudio: la definición de la base de la astenosfera (para el área de estudio completa y para profundidades variando desde 130 a 280 km, respectivamente).</p>

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