scholarly journals Digital seismograms of selected aftershocks of the Northridge earthquake recorded by a dense seismic array on February 11, 1994 at Cedar Hill Nursery in Tarzana, California

1994 ◽  
Author(s):  
W.H. Lee ◽  
R.A. White ◽  
D.H. Harlow ◽  
J.A. Rogers ◽  
Paul Spudich ◽  
...  
Keyword(s):  
Seismic Array ◽  
Northridge Earthquake ◽  
Digital Seismograms ◽  
Dense Seismic Array

P-wave backazimuth anomalies observed by a small-aperture seismic array at Pinyon Flat, southern California: Implications for structure and source location

1996 ◽  
Vol 86 (2) ◽  
pp. 470-476 ◽  
Author(s):  
Cheng-Horng Lin ◽  
S. W. Roecker
Keyword(s):  
Southern California ◽  
Seismic Array ◽  
P Wave ◽  
Small Aperture ◽  
Data Set ◽  
Single Interface ◽  
Seismic Networks ◽  
Dense Seismic Array ◽  
Beamforming Technique

Abstract Seismograms of earthquakes and explosions recorded at local, regional, and teleseismic distances by a small-aperture, dense seismic array located on Pinyon Flat, in southern California, reveal large (±15°) backazimuth anomalies. We investigate the causes and implications of these anomalies by first comparing the effectiveness of estimating backazimuth with an array using three different techniques: the broadband frequency-wavenumber (BBFK) technique, the polarization technique, and the beamforming technique. While each technique provided nearly the same direction as a most likely estimate, the beamforming estimate was associated with the smallest uncertainties. Backazimuth anomalies were then calculated for the entire data set by comparing the results from beamforming with backazimuths derived from earthquake locations reported by the Anza and Caltech seismic networks and the Preliminary Determination of Epicenters (PDE) Bulletin. These backazimuth anomalies have a simple sinelike dependence on azimuth, with the largest anomalies observed from the southeast and northwest directions. Such a trend may be explained as the effect of one or more interfaces dipping to the northeast beneath the array. A best-fit model of a single interface has a dip and strike of 20° and 315°, respectively, and a velocity contrast of 0.82 km/sec. Application of corrections computed from this simple model to ray directions significantly improves locations at all distances and directions, suggesting that this is an upper crustal feature. We confirm that knowledge of local structure can be very important for earthquake location by an array but also show that corrections computed from simple models may not only be adequate but superior to those determined by raytracing through smoothed laterally varying models.

scholarly journals Basic data features and results from a spatially dense seismic array on the San Jacinto fault zone

2015 ◽  
Vol 202 (1) ◽  
pp. 370-380 ◽  
Author(s):  
Yehuda Ben-Zion ◽  
Frank L. Vernon ◽  
Yaman Ozakin ◽  
Dimitri Zigone ◽  
Zachary E. Ross ◽  
...  
Keyword(s):  
Fault Zone ◽  
Seismic Array ◽  
Basic Data ◽  
San Jacinto Fault ◽  
San Jacinto Fault Zone ◽  
Dense Seismic Array

Remnants of the Amalgamation of the East and West Cathaysia Blocks Revealed by a Short-period Dense Seismic Array

2022 ◽  
Author(s):  
He Huang ◽  
Xuzhang Shen ◽  
Jian Xu ◽  
Rui Gao ◽  
Wentian Wang ◽  
...  
Keyword(s):  
Seismic Array ◽  
Short Period ◽  
East And West ◽  
Dense Seismic Array

Estimation of Direction of Wavefront Propagation and Slowness Using Time Domain Wavenumber Analysis in Small-Size Dense Seismic Arrays

2012 ◽  
Vol 479-481 ◽  
pp. 1186-1189
Author(s):  
Ping Liu ◽  
Hua Ma ◽  
Xue Wei Zhang ◽  
Xin Yu Sun ◽  
Fei Cao
Keyword(s):  
Time Domain ◽  
Seismic Array ◽  
Apparent Velocity ◽  
Seismic Signals ◽  
Analysis Method ◽  
Seismic Arrays ◽  
Wavefront Propagation ◽  
Pass Through ◽  
The Time Domain ◽  
Dense Seismic Array

The time domain wavenumber analysis method can directly delay and align signals before the superposition of signals in the time domain. In this paper, estimating the direction of wavefront propagation and the slowness for seismic signals which pass through the small-size dense seismic array is described in detail. The earthquake recorder sample adopted from US Geological Survey Parkfield Dense Seismograph Array (UPSAR array) of the U.S is used for analyzing. The results indicate that, the direction of wavefront propagation cannot be determined rashly only by the connecting line of the earthquake epicenter to the seismic array. The accuracy of the apparent velocity and the direction of wavefront propagation calculated using vertical seismic recorders is higher in West-East direction and in North-South direction.

scholarly journals An Observation System for a Dense Seismic Array Designed for Detecting Weak Reflected Phases from Deep Crust

1992 ◽  
Vol 45 (2) ◽  
pp. 255-258
Author(s):  
Shigeki HORIUCHI ◽  
Noriko TSUMURA ◽  
Akira HASEGAWA ◽  
Syuichiro HORI ◽  
Kouichi NIDA
Keyword(s):  
Seismic Array ◽  
Observation System ◽  
Deep Crust ◽  
Dense Seismic Array
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