This article presents decoupling n-times absorbing boundary conditions designed to model acoustic and elastic wave propagation in a 2D transversely isotropic (TI) medium. More general n-times boundary conditions with absorbing parameters are also obtained by cascading first-order differential operators with parameters. These boundary conditions are approximated with simple finite-difference sch...

The receiver function (RF) technique is a well-established method to investigate the crustal and upper mantle structures based on three-component seismograms of teleseismic events. In the present study, we propose a modified automatic procedure to determine the back azimuth and polarization angles of a teleseismic event based on the RF technique. The method is tested for the recording of 3 perm...

We propose a robust interpolation scheme for aliased regularly sampled seismic data that uses the curvelet transform. In a first pass, the curvelet transform is used to compute the curvelet coefficients of the aliased seismic data. The aforementioned coefficients are divided into two groups of scales: alias-free and alias-contaminated scales. The alias-free curvelet coefficients are upscaled to...

Full waveform inversion (FWI) can generate high-resolution subsurface models, but often suffers from an objective function with local minima caused mainly by an absence of low frequencies in seismograms. These local minima cause cycle skipping when the initial model for FWI is far from the true model. To avoid cycle skipping, traveltime inversion is often used to compute initial models for FWI....

Short- and long-period precursors of the PKP phase were used to study an ultra-low velocity zone (ULVZ) near the core-mantle boundary beneath the Western Pacific. Synthetic seismograms were computed from a hybrid method, which handles seismic wave propagation through two-dimensional complex structures. Long-period precursors were explained by Gaussian-shaped ULVZs of 60 to 80 kilometers height ...

[1] We applied the wavelet transform in an attempt to detect long-period components early in a seismogram. We analyzed the displacement seismograms of the 26 December 2004 Sumatra-Andaman earthquake (Mw = 9.2) and the 28 March 2005 Nias earthquake (Mw = 8.7). Wavelet analysis is able to clearly distinguish the amplitudes of the long-period W phase between the seismograms of the two earthquakes ...

Retrieving information from analog seismograms is of great importance since they are considered as the unique sources that provide quantitative information of historical earthquakes. We present an algorithm for automatic digitization of the seismograms as an inversion problem that forms an interactive program using Matlab GUI. The program integrates automatic digitization with manual digitizati...

-The focus-of-attention techniques implemented in SNA2, a knowledge-based system for seismogram interpretation, are presented. They consist of data compression of the input digital records, scanning of the compressed traces to detect candidate seismograms and extraction of seismogram features. A criterion is given to rate the clarity of seismograms; the clarity defines the order in which the sy...

Previous authors have tried to image seismic reflectivity by crosscorrelating passive seismic data, and treating the resultant correlograms as active source seismograms. We provide a mathematical framework for working with passive seismic correlograms that is both appropriate for V (x , y, z) media, and arbitrary source location. Under this framework, correlograms can be migrated with an imagin...