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...

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)...

Overburden layers continue to be a problem for recording and analyzing information in seismic surveys. This study aims to examine the effects of overburden layers on seismic wave propagation and imaging. In the investigation, we look at the effect of low velocity, low density overburden on seismic imaging. To investigate this problem, a finite difference elastic wave modelling study was conduct...

The disadvantages of conventional seismic tomographic ray tracing and inversion by calculus-based techniques include the assumption of a single ray path for each source– receiver pair, the non-inclusion of head waves, long computation times, and the difficulty in finding ray paths in a complicated velocity distribution. A ray-tracing algorithm is therefore developed using the reciprocity princi...

S U M M A R Y The seismic structure of large igneous provinces provides unique constraints on the nature of their parental mantle, allowing us to investigate past mantle dynamics from present crustal structure. To exploit this crust–mantle connection, however, it is prerequisite to quantify the uncertainty of a crustal velocity model, as it could suffer from considerable velocity–depth ambiguit...

Site U1325 (Prospectus Site CAS-02C) is located near the southwestern end of the marginperpendicular transect established during Expedition 311 and is within a major slope basin that developed eastward of the deformation front behind a steep ridge of accreted sediments. Bathymetry data show that the seafloor in the western part of this slope basin is relatively flat with water depths around 220...

[1] Using two continuum models of rate-and-state faults, one with a weaker patch and the other with rheological transition from steady state velocity-weakening to velocity-strengthening friction, we simulate several scenarios of spontaneous earthquake nucleation plausible for natural faults, investigate their response to static shear stress steps, and infer the corresponding aftershock rates. O...

[1] We determine the geometry and geographic distribution of a very low velocity province (VLVP) at the base of the Earth’s mantle beneath the South Atlantic and Indian Oceans, based on waveform modeling and travel time analysis of seismic data recorded in Africa. Our data sets consist of SH, ScS, SHdiff, SKS, and SKKS phases recorded at two temporary broadband PASSCAL seismic arrays in Africa,...