Measurements of ULF electromagnetic disturbances were carried out in Japan before and during a seismic active period (1 February 2000 to 26 July 2000). A network consists of two groups of magnetic stations spaced apart at a distance of ≈ 140 km. Every group consists of three, 3component high sensitive magnetic stations arranged in a triangle and spaced apart at a distance of 4–7 km. The results...

Seismic waves are non-stationary due to its propagation through the earth. Time-frequency transforms are suitable tools for analyzing non-stationary seismic signals. Spectral decomposition can reveal the non-stationary characteristics which cannot be easily observed in the time or frequency representation alone. Various types of spectral decomposition methods have been introduced by some resear...

A d-dimensional polycube is a facet-connected set of cubes in d dimensions. Fixed polycubes are considered distinct if they differ in their shape or orientation. A proper d-dimensional polycube spans all the d dimensions, that is, the convex hull of the centers of its cubes is d-dimensional. In this paper we prove rigorously some (previously conjectured) closed formulae for fixed (proper and im...

In this work, an analysis method is developed for the robust and efficient estimation of 3-D seismic local structural entropy, which is a measure of local discontinuity. This method avoids the computation of large covariance matrices and eigenvalues, associated with the eigenstructure-based and semblance-based coherency estimates. We introduce a number of local discontinuity measures, based on ...

Estimation of the fast polarization direction of shear seismic waves that deviate from horizontal axis is a valuable approach to investigate the characteristics of the lower crust and uppermost mantle structures. The lattice preferred orientation of crystals, which is generally parallel to the downward or upward flow of the mantle or crust, is an important reason for the occurrence of fast axis...

seismic waves are non-stationary due to its propagation through the earth. time-frequency transformsare suitable tools for analyzing non-stationary seismic signals. spectral decomposition can reveal thenon-stationary characteristics which cannot be easily observed in the time or frequency representationalone. various types of spectral decomposition methods have been introduced by some researche...

In this study, the seismic interaction of surface foundations and underground cavities was investigated. For this purpose, a parametric study of geometric dimensions of the foundation and cavity, their location, and the effect of the interaction between surface foundations and underground cavities was evaluated. The variable parameters include the ratio of the overburden height to the foundatio...

Remote detection and characterization of fractured reservoirs is facilitated in this project by developing a revolutionary software system. The Model-Automated Geo-Informatics (MAGI) software integrates basin modeling, seismic data, synthetic seismic wave propagation and well data via information theory. The result is a seismic inversion cast in terms of fracture and other reservoir characteris...

S U M M A R Y We demonstrate that the distribution of seismic noise sources affects the accuracy of Green’s function estimates and therefore isotropic and anisotropic tomographic inversions for both velocity and attenuation. We compare three methods for estimating seismic noise source distributions and quantify the potential error in phase velocity, azimuthal anisotropy and attenuation estimate...

This article presents a Matlab-based educational software developed at Aristotle University of Thessaloniki in Greece, in order to familiarize students and young engineers with fundamental concepts of structural dynamics and, in particular, soil–structure interaction problems. This user-friendly educational tool aims to assist the students in comprehending the nature of this complex phenomenon ...