scholarly journals A simple P-wave polarization analysis: its application to earthquake location

1994 ◽  
Vol 37 (5) ◽  
Author(s):  
B. Alessandrini ◽  
M. Cattaneo ◽  
M. Demartin ◽  
M. Gasperini ◽  
V. Lanza
Keyword(s):  
Ground Motion ◽  
Seismic Wave ◽  
Heterogeneous Media ◽  
Seismic Wave Propagation ◽  
Least Square ◽  
P Wave ◽  
Motion Direction ◽  
Arrival Times ◽  
Hypocentral Location ◽  
Ray Path

We present a method for hypocentral location which takes into account all three components of ground motion and not only the vertical one, as it is usually done by standard least-square techniques applied to arrival times. Assuming that P-wave particle motion direction corresponds to the propagation direction of the seismic wave, we carried out a simple statistical analysis of ground motion amplitudes, carefully using three-component records. We obtained the azimuth and the emersion angle of the seismic ray, which, added to Pg and Sg arrival times, allowed us to find reliable hypocentral coordinates of some local events by means of a ray-tracing technique. We compared our locations to those obtained using a least-square technique: our polarization method's dependence on the accuracy of the model used (on the contrary, the least-square technique proved to be quite stable with respect to changes in the model's velocity parameters) led us to conclude that polarization data provide coherent information on the true ray-path and can be successfully used for both location procedures and seismic wave propagation studizs in strongly heterogeneous media.

Seismic Wave Propagation and Basin Amplification in the Wasatch Front, Utah

2021 ◽  
Author(s):  
Morgan P. Moschetti ◽  
David Churchwell ◽  
Eric M. Thompson ◽  
John M. Rekoske ◽  
Emily Wolin ◽  
...  
Keyword(s):  
Wave Propagation ◽  
Ground Motion ◽  
Seismic Wave ◽  
Seismic Velocity ◽  
Site Response ◽  
Ground Motions ◽  
Seismic Wave Propagation ◽  
Velocity Models ◽  
Ground Motion Variability ◽  
Wasatch Front

Abstract Ground-motion analysis of more than 3000 records from 59 earthquakes, including records from the March 2020 Mw 5.7 Magna earthquake sequence, was carried out to investigate site response and basin amplification in the Wasatch Front, Utah. We compare ground motions with the Bayless and Abrahamson (2019; hereafter, BA18) ground-motion model (GMM) for Fourier amplitude spectra, which was developed on crustal earthquake records from California and other tectonically active regions. The Wasatch Front records show a significantly different near-source rate of distance attenuation than the BA18 model, which we attribute to differences in (apparent) geometric attenuation. Near-source residuals show a period dependence of this effect, with greater attenuation at shorter periods (T<0.5  s) and a correlation between period and the distance over which the discrepancy manifests (∼20–50  km). We adjusted the recorded ground motions for these regional path effects and solved for station site terms using linear mixed-effects regressions, with groupings for events and stations. We analyzed basin amplification by comparing the site terms with the basin geometry and basin depths from two seismic-velocity models for the region. Sites over the deeper parts of the sedimentary basins are amplified by factors of 3–10, relative to sites with thin sedimentary cover, with greater amplification at longer periods (T≳1  s). Average ground-motion variability increases with period, and long-period variability exhibits a slight increase at the basin edges. These results indicate regional seismic wave propagation effects requiring further study, and potentially a regionalized GMM, as well as highlight basin amplification complexities that may be incorporated into seismic hazard assessments.

scholarly journals Seismic Wave Propagation Simulation in a Poro-elastic Medium Using Spectral Method Elements in MPI-GPU Cluster: Study Case of Anticline Reservoir Trap

2019 ◽  
Vol 9 (01) ◽  
pp. 9
Author(s):  
Sudarmaji Sudarmaji ◽  
Indra Rudianto ◽  
Muhammad Kautsar Rahmareza ◽  
Yosua Alfontius
Keyword(s):  
Wave Propagation ◽  
Elastic Medium ◽  
Seismic Wave ◽  
Computation Time ◽  
Seismic Wave Propagation ◽  
P Wave ◽  
Surface Boundary ◽  
Reservoir Rocks ◽  
Hydrocarbon Reservoir ◽  
Model Free

Modeling 2D seismic wave propagation using spectral element method on MPI-GPU clusters has been implemented and can complete the problem of elastic-poro elastic medium model. Free surface boundary conditions and absorption layer will use the CPML method. Seismic wave propagation simulation in hybrid elastic-poroelastic medium has been carried out on hydrocarbon reservoir models with anticline type. In reservoir rocks that have a poro elastic medium, there will be a fast and slow P wave. While in non-reservoir rocks that have elastic medium, only P fast waves is observed. The computation time for an anticline type reservoir model with dimensions of 1 km x 1.5 km using MPI 4 nodes cluster with 48 CPU cores is 3 minutes 48 second.

scholarly journals Fast Marching Method Aplication for Forward Modelling of Seismic Wave Propagation

2018 ◽  
Vol 16 (3) ◽  
pp. 1
Author(s):  
Wahyu Srigutomo ◽  
Ghany Hanifan Muslim
Keyword(s):  
Wave Propagation ◽  
Viscosity Solution ◽  
Seismic Wave ◽  
Eikonal Equation ◽  
Heterogeneous Media ◽  
Seismic Wave Propagation ◽  
Time Travel ◽  
Fast Marching Method ◽  
Fast Marching ◽  
Marching Method

One of the classical problem in seismology is to determine time travel and ray path of seismic wave betweentwo points at a given heterogeneous media. This problem is expressed by eikonal equation and can be seen as a propagation of a wavefront and interface evolution. One of methods to solve this problem is Fast Marching Method abbreviated as FMM. This method is used to produce entropy-satisfying viscosity solution of eikonal equation. FMM combines viscosity solution of Hamilton-Jacobi equation and Huygen's Principle that centered on min-heap data structure to determine the minimum value at every loop. In this study, FMM is applied to determine time travel and raypath of seismic wave. FMM also is used to determine the location of wavesource using simple algorithm. From our forward modeling schemes, it is found that FMM is an accurate, robust, and effcient method to simulate seismic wave propagation. For further study, FMM also can be used to be a part of passive seismic inverse scheme to locate hypocenter location.

Sign in / Sign up

Export Citation Format

Share Document