We have investigated energy amplification observed within Greater Los Angeles basin by analyzing regional waveforms recorded from several Nevada Test Site (NTS) nuclear explosions. Although the stations are located nearly at the same azimuth (distances ranging from 350 to 400 km), the seismograms recorded in Compton (the central part of the basin), Long Beach (the southern edge of the basin), a...

We present a source model for the beginning of earthquakes based on the Griffith's fracture criterion. The initial state is a critical state of pre-existing circular fault, which is on the verge of instability. After the onset of instability, the fault grows with a progressively increasing rupture speed, satisfying the condition of fracture energy balance at the crack tip. We investigate the di...

Figure 2.16: Models, seismograms and maximum amplitude distributions for two models with a fault widening towards the surface and a low velocity layer on top.. Figure 2.17: Selected seismograms, amplitude spectra and envelopes for the two models with a fault widening towards the surface and a low velocity layer on top .. Figure 4.10: Seismogram comparison of synthetics calculated with the refle...

The single-scattering (or Born) approximation is the most fundamental assumption shared by all seismic imaging methods, and plays a crucial role in the nonlinear waveform inversion, an iterative process of linearized inversions. The Born simulator (linearized forward map) shares a computational core with the corresponding simulator (forward map), which has been well implemented in the modeling ...

Abstract Shear-wave splitting (SWS), or the propagation of two independent shear waves, can be used as an indicator seismic anisotropy. In this study, we utilize concept using aftershock data 2018 Lombok earthquake which had been acquired in period August 4 – September 9, 2018. The goal research is to better understand crack distribution related rupture zone earthquake. After applying instrumen...

Observations of seismic waves from earthquakes at depths between 100 and 200 km beneath Japan show that the initial portion of the S-wave arrival has greater duration than can be accounted for by earthquake source-time duration. The observed long duration of S waves has been explained as being caused by multiple forward scattering around the ray path between source and receiver. Array observati...

We propose a modification to the Non-linear Asymptotic Coupling Theory (NACT), a normal mode coupling method used for synthesizing seismograms and computing sensitivity kernels in 3D Earth. The modification is aimed to meet the computational challenges for NACT when approaching higher frequencies, which is required for obtaining finer scale images of the Earth's upper mantle. The new scheme is ...