During an earthquake, the motion of the ground spatially changes, in both amplitude and phase. The spatial variation of seismic ground motions has an important effect on the response of large structures such as bridges and dams. To be able to simulate seismic ground motions which vary in space, a representing spatial variability model is required. Data collected from closely spaced arrays of se...

Shear wave seismic-acoustic imaging incorporating laser Doppler vibrometers (LDV) has been successfully used to detect buried landmines using single tone excitation. In this paper, the use of linear frequency modulated (LFM) chirps is proposed to exploit wideband resonant behavior. This technique captures more information about complex elastic inhomogeneities while being more tolerant to noise.

The presence of natural fractures in reservoir rock can significantly enhance gas production, especially in tight gas formations. Any general knowledge of the existence, location, orientation, spatial density, and connectivity of natural fractures, as well as general reservoir structure, that can be obtained prior to active seismic acquisition and drilling can be exploited to identify key areas...

In this paper, we study the excitation of the Earth's polar motion in connection wit] M; ^Pare associated with the diversity of reference frames involved in observations and theoretical computations. Thus, following the dynamics of the Earth's polar motion, the kinematics that relates observations from different reference frames is developed. The conventional procedures of studying the seismic ...

A numerical study is presented of the dynamic response of end-bearing piles embedded in a number of idealized soil deposits and subjected to vertically propagating harmonic S-waves. Results, for both 'kinematic' and 'inertial' interaction, are offered in the form of dimensionless graphs and formulae covering a wide range of excitation frequencies and of crucial material and geometric parameters...

S U M M A R Y Recent development in seismology has shown that seismic noise is a useful source of Earth structure study. Non-linear interaction of ocean waves is considered to be one of the important causes for seismic noise, although source locations and detailed mechanisms are not clear yet. In order to improve our understanding of this mechanism quantitatively, we derive a normal-mode excita...

Torsion of many symmetric structures, which were designed based on the seismic codes, is due to their asymmetricity induced during inelastic behavior. Although the structure was designed symmetrically assuming elastic based criteria, different factors such as material inconsistency in structure, construction details discrepancy and construction errors may result in asymmetric behavior in inelas...