Seismic waves due to a dislocation source model in a multi-layered medium. III. Numerical calculations for a moving fault.

Seismic waves in a layered half-space with lateral inhomogeneities, generated by a buried seismic dislocation source, are investigated in these two consecutive papers. In the first paper, the problem is formulated and a corresponding approach to solve the problem is provided. Specifically, the elastic parameters in the laterally inhomogeneous layer, such as P and S wave speeds and density, are separated by the mean and the deviation parts. The mean part is constant while the deviation part, which is much smaller compared to the mean part, is a function of lateral coordinates. Using the first-order perturbation approach, it is shown that the total wave field may be obtained as a superposition of the mean wave field and the scattered wave field. The mean wave field is obtainable as a response solution for a perfectly layered half-space (without lateral inhomogeneities) subjected to a buried seismic dislocation source. The scattered wave field is obtained as a response solution for the same layered half-space as used in the mean wave field, but is subjected to the equivalent fictitious distributed body forces that mathematically replace the lateral inhomogeneities. These fictitious body forces have the same effects as the existence of lateral inhomogeneities and can be evaluated as a function of the inhomogeneity parameters and the mean wave fleld. The explicit expressions for the responses in both the mean and the scattered wave fields are derived with the aid of the integral transform approach and wave propagation analysis.

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VELOCITY ANISOTROPY MEASUREMENTS IN WELLS

Geophysics ◽

10.1190/1.1439822 ◽

1966 ◽

Vol 31 (5) ◽

pp. 900-916 ◽

Cited By ~ 19

Author(s):

D. M. Vander Stoep

Keyword(s):

Seismic Waves ◽

Layered Medium ◽

Sedimentary Rocks ◽

Transversely Isotropic ◽

Anisotropy Factor ◽

Propagation Time ◽

Reflection Seismology ◽

Simple Description ◽

Velocity Anisotropy ◽

The Difference

Sedimentary rocks are generally anisotropic to the propagation of seismic waves. Anisotropy can be defined as the difference between propagation time predicted by the simple theory of Snell’s Law and observed propagation time between two points in a layered medium that lie on a line oblique to the layers. This difference can be explained by the more complicated theory of wave propagation in transversely isotropic materials. In the zone about the vertical that is of interest in reflection seismology, the effect of anisotropy usually can be described geometrically by an anisotropy factor A. This simple description is not valid for propagation directions making large angles with the normal to the layers. The anisotropy factor as well as the vertical velocity can vary with depth. A method is given for determining the factor A as a function of depth from a continuous velocity log and a range of oblique shots into a well phone. The method is applied to two field examples. In one of the examples, it is shown by data obtained from the larger shooting distances that the simple A factor description is inadequate for higher angles of propagation direction.

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Numerical Simulation of Tsunami Run-Up and Inundation for the 2011 Tōhuku-Oki Tsunami: A Parametric Analysis for Tsunami Run-Up and Wave Height

Volume 8A: Ocean Engineering ◽

10.1115/omae2014-23138 ◽

2014 ◽

Author(s):

Debashis Basu ◽

Robert Sewell ◽

Kaushik Das ◽

Ron Janetzke ◽

Biswajit Dasgupta ◽

...

Keyword(s):

Wave Propagation ◽

Wave Height ◽

Seismic Waves ◽

Source Model ◽

Tsunami Source ◽

Computational Framework ◽

Wave Amplification ◽

Source Models ◽

Run Up ◽

Tsunami Run Up

This paper presents computational results for predicting earthquake-generated tsunami from a developed integrated computational framework. The computational framework encompasses the entire spectrum of modeling the earthquake-generated tsunami source, open-sea wave propagation, and wave run-up including inundation and on-shore effects. The present work develops a simplified source model based on pertinent local geologic and tectonic processes, observed seismic data (i.e., data obtained by inversion of seismic waves from seismographic measurements), and geodetic data (i.e., directly measured seafloor and land deformations). These source models estimated configurations of seafloor deformation used as initial waveforms in tsunami simulations. Together with sufficiently accurate and resolved bathymetric and topographic data, they provided the inputs needed to numerically simulate tsunami wave propagation, inundation and coastal impact. The present work systematically analyzes the effect of the tsunami source model on predicted tsunami behavior and the associated variability for the 2011 Tōhuku-Oki tsunami. Simulations were carried out for the 2011 Tōhuku -Oki Tsunami that took place on March 11, 2011, from an MW 9.1 earthquake. The numerical simulations were performed using the fully nonlinear Boussinesq hydrodynamics code, FUNWAVE-TVD (distributed by the University of Delaware). In addition, a sensitivity analysis was also carried out to study the effect of earthquake magnitude on the predicted wave height. The effect of coastal structure on the wave amplification at the shore is also studied. Simulated tsunami results for wave heights are compared to the available observational data from GPS (Global Positioning System) at the central Miyagi location.

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Deformation Source Revealed From Leveling Survey in Jigokudani Valley, Tateyama Volcano, Japan

10.21203/rs.3.rs-989577/v1 ◽

2021 ◽

Author(s):

Kohei Hotta ◽

Shigekazu Kusumoto ◽

Hidenori Takahashi ◽

Yuichi S Hayakawa

Keyword(s):

Source Model ◽

Deformation Source ◽

Bench Mark ◽

Interferometric Synthetic Aperture Radar ◽

Dislocation Source ◽

Grid Search Method ◽

Current Maximum ◽

Western Side ◽

One Year ◽

Gas Chamber

Abstract We modeled vertical deformation detected from leveling survey in Jigokudani valley, Tateyama volcano, central Japan. In Jigokudani valley, uplift of 4 cm/year was previously detected during the period from 2007 to 2010 by Interferometric Synthetic Aperture Radar (InSAR). To confirm whether this inflation has continued to the present, we conducted leveling survey in Jigokudani valley since 2015. Most bench marks showed subsidence up to 5.6 cm during the four-year period from October 2016 to September 2020, while a bench mark locates at the center of the leveling route uniquely showed uplift of 1.6 cm. We applied a dislocation source model to the deformation using a grid search method. A crack with a length of 350 m, a width of 100 m, a strike of N117°E and a dip of 61° is located at a depth of 50 m near the center of Jigokudani valley (Koya jigoku and the new fumarolic area) where highly activating recently. Closing of the crack of 344 cm yields volume decreases of 120,400 m3. Striking direction of the crack is parallel to the line of which are old explosion craters (Mikurigaike and Midorigaike ponds) and corresponds to current maximum compressive stress field in the region of Hida Mountains including Tateyama volcano. The deformation source of the previous period from 2007 to 2010 detected from InSAR was estimated to be at a depth of 50 m and a gas chamber was correspondingly found from the audio-frequency magnetotelluric (AMT) survey. The estimated crack in this study is also located at a similar position of the gas chamber which was also identified from AMT survey. During the period from 2015 to 2016, the crack opened (i.e., inflated) and the inflation stopped during the next one-year period from 2016 to 2017. During the period from 2017 to 2020, the crack turned to closing (i.e., deflation), probably because of the increase in emission of volcanic fluid or gas with a formation of a new crater at the western side of Jigokudani valley (Yahata jigoku) during the period from 2017 to 2018.

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Model for Calculating Seismic Wave Spectrum Excited by Explosive Source

Shock and Vibration ◽

10.1155/2021/6544453 ◽

2021 ◽

Vol 2021 ◽

pp. 1-15

Author(s):

Qian Xu ◽

Zhong-Qi Wang

Keyword(s):

Seismic Wave ◽

Seismic Waves ◽

Wave Spectrum ◽

Seismic Source ◽

Source Model ◽

Detonation Pressure ◽

Adiabatic Expansion ◽

Main Frequency ◽

Explosive Source ◽

Seismic Source Model

To reveal the characteristics and laws of the seismic wavefield amplitude-frequency excited by explosive source, the method for computing the seismic wave spectrum excited by explosive was studied in this paper. The model for calculating the seismic wave spectrum excited by explosive source was acquired by taking the seismic source model of spherical cavity as the basis. The results of using this model show that the main frequency and the bandwidth of the seismic waves caused by the explosion are influenced by the initial detonation pressure, the adiabatic expansion of the explosive, and the geotechnical parameters, which increase with the reduction of initial detonation pressure and the increase of the adiabatic expansion. The main frequency and the bandwidth of the seismic waves formed by the detonation of the explosives in the silt clay increase by 23.2% and 13.6% compared to those exploded in the silt. The research shows that the theoretical model built up in this study can describe the characteristics of the seismic wave spectrum excited by explosive in a comparatively accurate way.

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A mechanism-based homogenization of a dislocation source model for bending

Acta Materialia ◽

10.1016/j.actamat.2018.11.013 ◽

2019 ◽

Vol 164 ◽

pp. 663-672 ◽

Cited By ~ 3

Author(s):

Severin Schmitt ◽

Markus Stricker ◽

Peter Gumbsch ◽

Katrin Schulz

Keyword(s):

Source Model ◽

Dislocation Source

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Long-period surface velocities and accelerations due to a dislocation source model in a medium with superficial multi-layers. II.

Journal of Physics of the Earth ◽

10.4294/jpe1952.26.17 ◽

1978 ◽

Vol 26 (1) ◽

pp. 17-37 ◽

Cited By ~ 1

Author(s):

Ryosuke SATO

Keyword(s):

Source Model ◽

Dislocation Source ◽

Long Period

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Amplitudes and energies of primary seismic waves near the hardhat, haymaker, and shoal nuclear explosions

Bulletin of the Seismological Society of America ◽

10.1785/bssa0560030643 ◽

1966 ◽

Vol 56 (3) ◽

pp. 643-653 ◽

Cited By ~ 1

Author(s):

Lynn D. Trembly ◽

Joseph W. Berg

Keyword(s):

Theoretical Model ◽

Seismic Waves ◽

Theoretical Data ◽

Source Model ◽

Similar Data ◽

Underground Nuclear Explosions ◽

Nuclear Explosions ◽

Long Period ◽

Radiation Fields ◽

Amplitude Data

abstract Records of near-source (0.3 to 20 km) primary seismic waves generated by the Hardhat, Haymaker, and Shoal underground nuclear explosions were analyzed in terms of displacement amplitude and energy variations with distance. The observed data were compared to similar data from a theoretical source model to determine the adequacy of the theoretical model. There was evidence that a long-period displacement field existed near the explosions as predicted by the theoretical source. Scatter in the observed amplitude data made it difficult to distinguish between the long-period and the radiation fields. However, the variation of total energy of the observed primary seismic waves with distance showed the presence of the long-period field. The comparison of observed and theoretical data indicates that a theoretical elastic source model approximated the observed sources.

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