We applied a tomographic method to image an aseismic strike–slip fault in North Morocco and found that the occurrence of earthquakes is not only controlled by the state of tectonic stress but also by material heterogeneity in the crust. We have constructed an integrated model of seismic, electric, magnetic and heat flow properties across northeastern Morocco primarily based on a tomography inve...

We estimate shear-wave velocities in the shallow subsurface throughout Japan by applying seismic interferometry to the data recorded with KiK-net, a strongmotion network in Japan. Each KiK-net station has two receivers; one receiver on the surface and the other in a borehole. By using seismic interferometry, we extract the shear wave that propagates between these two receivers. Applying this me...

We have conducted a series of experiments designed to investigate elastic and electromagnetic (EM) velocity anisotropy associated with a preferentially aligned fracture system on a temperate valley glacier in south-central Alaska, USA. Measurements include a three-dimensional compressional wave (P-wave) seismic reflection survey conducted over a 300m 300m survey patch, with uniform source grid ...

The utility of the multi-channel analysis of surface waves (MASW) seismic method for noninvasive assessment of earthen levees was evaluated for a section of the Citrus Lakefront Levee, New Orleans, Louisiana. This test was conducted after the New Orleans’ area levee system had been stressed by Hurricane Katrina in 2005. The MASW data were acquired in a seismically noisy, urban environment using...

[1] In this study, we analyzed the seismic phases S, SKS, and SKKS from 31 deep-focus earthquakes in the Tonga-Fiji region recorded in North America between epicentral distances of 85 and 120 . The differential traveltimes and amplitude ratios for these phases reveal clear epicentral distance trends not predicted by standard one-dimensional (1-D) reference Earth models. The increase of the S/SK...

In a previous study published in this journal, the authors developed a comprehensive methodology for modelling the shear wave velocity profile in crustal rock, for purposes of seismic hazard assessment. The derived shear wave velocity profile was used to estimate the amplification and attenuation mechanisms in the transmission of seismic waves. The ability to conduct seismic hazard assessments ...

[1] Imaging of seismic velocity discontinuities along a 3000 km profile across central South America at 20 S suggests that the depth variations of the 410-km (d410) and 660-km (d660) discontinuities are closely associated with the high-velocity Nazca slab and juxtaposed low-velocity oceanic mantle beneath the slab. The mantle transition zone thickness ranges from 220 km in the oceanic mantle to...

S U M M A R Y Wide-angle seismic reflection traveltimes generated by large explosions are used extensively to obtain both velocity and regional structure of the crust and upper mantle. The method most commonly used to calculate interval velocities and thicknesses (layer parameters) of a multilayered earth. supposed to consist of homogeneous, isotropic and horizontal layers, is based on Dix’s ( ...

In this dissertation, I investigate the assembly and evolution of the Archean cratonic lithosphere by using two complementary seismological methods to image the lithospheric structure of the Slave craton in Canada. First, I perform surface wave tomographic inversions to constrain the depth dependence of Rayleigh wave phase velocity, shear wave velocity, and azimuthal anisotropy of the Slave cra...

Worldwide interest in shale plays has rapidly increased in recently years, thanks to the combination of horizontal drilling and hydraulic fracturing. Shale formations act as both the source and the reservoir for the natural gas and usually exhibit anisotropic properties at larger scale. Geological and petropysical studies found that the right combination of thickness, TOC (total organic carbon)...