We deployed a dense linear array of 45 seismometers across and along the San Andreas fault near Parkfield a week after the M 6.0 Parkfield earthquake on 28 September 2004 to record fault-zone seismic waves generated by aftershocks and explosions. Seismic stations and explosions were co-sited with our previous experiment conducted in 2002. The data from repeated shots detonated in the fall of 20...

One way of developing a wave-equation approach to seismic imaging is based on the concept of downward continuation of the 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. The downward continued data are subjected, at each depth,...

pore pressure could be estimated prior to drilling using seismic velocities. applying this approach, the final calculated pore pressure is highly affected by accuracy of the obtained velocity data. in order to generate an accurate velocity cube with proper resolution, velocities from well logs and post-stack 3-d seismic inversion are used along with stacking velocities from velocity analysis of...

In this article, we analyze the dynamic characteristics of head wave in multi-layered half-space media models with high-velocity layer or low-velocity layer, and the model with a continuous transition-zone between the crust and the mantle by using synthetic seismogram. It is concluded that the dynamic characteristics of head wave are sensitive to the thickness and velocity of the high-velocity ...

summarythe explanation of the elastic, or velocity structure of the earth has long been a goal of the world’s seismologists. for the first few decades of seismological research, the investigation on velocity structure was restricted to the determination of one-dimensional models of the solid earth and of various regions within it. seismologists are currently obtaining three dimensional velocity...

A recent dense deployment of seismic stations in South Korea and Japan allows regional seismic imaging of the far-east Asian region that experienced continental collisions and riftings. We perform seismic imaging based on a mantlelid P-wave (Pn) travel-time tomography to exploit the tectonic imprints in the lithosphere. The average Pn velocity in the region is estimated to be 7:95 0:03 km=sec. ...

Seismic studies using well-logging, refraction, and reflection methods were carried out in 1965 in conjunction with a core-sample drilling project in the Ewa Coastal Plain, Oahu, Hawaii. The seismic well-logging technique gave a complicated velocity-depth profile, with higher velocities associated with reef limestone and lower velocities associated with mud deposits. The seismic refraction meth...

Ultralow velocity zones are the largest seismic anomalies in the mantle, with 10-30% seismic velocity reduction observed in thin layers less than 20-40 km thick, just above the Earth's core-mantle boundary (CMB). The presence of silicate melts, possibly a remnant of a deep magma ocean in the early Earth, have been proposed to explain ultralow velocity zones. It is, however, still an open questi...