[1] We collected a new data set of 1354 broadband SPdKS waveforms sampling the western Pacific Ocean region. These data indicate that multiple ultralow-velocity zones (ULVZs) exist in this region. We compared these data to 2.5-D synthetic seismograms computed with the PSVaxi method for a suite of 517 ULVZ models. The region beneath the North and South Philippine Sea shows no evidence for ULVZ p...

The youth of seismology as a science, compared to the typical duration of seismic cycles, results in a relative scarcity of records of large earthquakes available for processing by modern analytical techniques, which in turn makes archived datasets of historical seismograms extremely valuable in order to enhance our understanding of the occurrence of large, destructive earthquakes. Unfortunatel...

By comparing records of the radial component of motion of teleseismic P waves to records of the vertical component, it is possible to identify S phases within the P wave form. These phases are generated by the mechanism of P to S conversion at discontinuities in velocity under the receiving station. Similar phases of the S to P converted type appear as precursors to the direct SV arrival. Model...

Abstract In this paper, we propose a novel picking algorithm for the automatic P- and S-waves onset time determination. Our is based on variance piecewise constant models of earthquake waveforms. The effectiveness robustness our are tested both synthetic seismograms real data. We simulate seismic events with different magnitudes (between 2 5) recorded at epicentral distances 10 250 km). For app...

We present progress in the development of a new approach to develop and evaluate earth models at the regional scale that utilizes full waveform seismograms. We have recently implemented a non-linear three-dimensional (3-D) Born approximation and constructed a 3-D shear velocity model of a subregion of Southeast Asia (longitude 75 to 150 degrees and latitude 0 to 45 degrees) based on this approa...

Petrophysical properties of cylindrical core specimens from three boreholes the International Continental Scientific Drilling Program, DSeis project, measured at ambient pressure and room temperature conditions in various laboratories are presented compared with downhole petrophysical data (sonic density). The sixty-six rock constituting metasediments, metabasalts intrusives. Seismic velocities...