S U M M A R Y We use idealized subduction megathrust models to examine aseismic, frictional fault creep throughout the interseismic period. We consider rate-dependent and rateand state-dependent friction. When there is significant post-seismic creep surrounding locations of coseismic slip, the creep rates surrounding an asperity may be lower than the plate convergence rate late in the seismic c...

Subsurface rock properties are manifested in seismic records as variations in traveltimes, amplitudes, and waveforms. It is commonly acknowledged that traveltimes are sensitive to the long wavelength part of the velocity, whereas amplitudes are sensitive to the short wavelength part of the velocity. The inherent sensitivity of seismic velocity at different wavelengths suggests an approach that ...

\Velocity Picking" is the problem of picking velocity-time pairs based on a coherence metric between multiple seismic signals. Coherence as a function of velocity and time can be expressed as a 2-D color image representing the \Semblance Velocity." Currently, humans pick velocities by looking at the Semblance Velocity image; picking velocities for a seismic survey can take days or even weeks. A...

The ultimate goal for seismic depth imaging is to find new hydrocarbon prospects or improve existing ones. High quality seismic data and an accurate velocity model are the main drivers for good imaging. Prospects may be identified on seismic data in areas which can range from high to low signal. Roughly speaking, prospects generated for shallow targets will be on good signal data and prospects ...

In this work, an effective technique for the measurement of seismic wave propagation velocity in the real geological medium is presented. The propagation velocities of seismic waves vary in different types of geological media from 100 m/s to 6800 m/s. Due to this, it is necessary to evaluate the propagation of the seismic wave front between the different points in the real media. The signal tim...

The Earth's core is mostly an Fe-Ni alloy with a fraction of light elements (~10 wt%, mainly O, S and Si). Accumulation of these light elements under the core-mantle boundary (CMB) may lead to chemical stratification. Seismic observations have been presented both for and against the stratification in the topmost region of the outer core. Here we investigate the structure under the CMB using dif...

Receiver functions derived from body waves recorded in Iceland and on the Hawaiian Islands reveal a seismic velocity discontinuity at about 1050 km depth beneath the two regions of presumed mantle upwelling. The waveforms of the converted phases from the mid-mantle discontinuity indicate a velocity increase with depth. The lack of consistent scattering found in recent systematic searches for se...

Time-lapse seismic data are widely used for monitoring subsurface changes. A quantitative assessment of how reservoir properties have changed allows for better interpretation of fluid substitution and migration during processes like oil and gas production, and carbon sequestration. Full waveform inversion has been proposed as a way to retrieve quantitative estimates of subsurface properties thr...

Repeated earthquakes and explosions recorded at the San Andreas fault (SAF) near Parkfield before and after the 2004 M6 Parkfield earthquake show large seismic velocity variations within an approximately 200m-wide zone along the fault to depths of approximately 6 km. The seismic arrays were co-sited in the two experiments and located in the middle of a high-slip part of the surface rupture. Wav...

Synthetic seismograms produced by the finite difference method are used to study the scattering of elastic and acoustic waves in two-dimensional media with random spatial variations in seismic velocity. The results of this study provide important insights about the propagation of short-period (< 1 s) seismic waves in the earth's crust and place significant constraints on the fluctuation spectru...