Seismic velocity changes and nonvolcanic tremor activity in the Parkfield area in California reveal that large earthquakes induce long-term perturbations of crustal properties in the San Andreas fault zone. The 2003 San Simeon and 2004 Parkfield earthquakes both reduced seismic velocities that were measured from correlations of the ambient seismic noise and induced an increased nonvolcanic trem...

in this study, we used teleseismic data which was recorded by 5 stations (dhr, ghg, kom, lin and vis) of the kermanshah seismic network from 2003 to 2007 with mb?5.5 and epicentral distances from 30° to 95°. the crustal structure beneath these stations was determined by the modeling of the p receiver functions. the main phases, which were observed in our final p receiver functions, are moho con...

We address the problem of estimating seismic velocities inside the earth which is necessary for obtaining seismic images in regular Cartesian coordinates. We derive a relation between the true seismic velocities and the routinely obtained so called ”time migration velocities”, which are some kind of mean velocities. We formulate an inverse problem and show that it is ill-posed. We suggest three...

S U M M A R Y One way of developing a wave-equation approach to seismic imaging is based on the concept of downward continuation of observed surface reflection data. Seismic imaging is typically based on the single scattering approximation, and assumes the knowledge of a smooth background model in which the mentioned downward continuation is carried out using the double-squareroot (DSR) equatio...

The refraction inverse problem was initially investigated by Herglotz (1907), Bateman (1910), and Wiechert and Geiger (1910) who applied Abel transforms for the inversion of seismic travel-times in radially varying media. For smoothly varying media in the absence of low velocity zones, this formulation provides an inverse solution which includes ray bending. In the presence of low velocity zone...

Seismic methods play an important role in the development of tight fractured reservoirs with substantial spatial variability of fracture density. Here, we apply a comprehensive processing sequence designed for layered azimuthally anisotropic media to wide-azimuth P-wave data acquired over a fractured gas sand formation in the Rulison field, Colorado. The main processing steps include nonhyperbo...

Ljubljana, the capital of Slovenia, is located in the central region of the country in a shallow sedimentary basin filled with Quaternary deposits. It is one of the most seismically active regions in Slovenia, with some important historical earthquakes that have caused damage and economic losses. The soft sediments are some of the most important factors responsible for the amplification of seis...

We investigated upper crustal structure with data from a dense seismic array deployed around Mount St. Helens for 2 weeks in the summer of 2014. Interstation cross correlations of ambient seismic noise data from the array were obtained, and clear fundamental mode Rayleigh waves were observed between 2.5 and 5 s periods. In addition, higher-mode signals were observed around 2 s period. Frequency...