scholarly journals Crustal Deformation in Southern California Constrained by Radial Anisotropy From Ambient Noise Adjoint Tomography

2020 ◽  
Vol 47 (12) ◽  
Author(s):  
Kai Wang ◽  
Chengxin Jiang ◽  
Yingjie Yang ◽  
Vera Schulte‐Pelkum ◽  
Qinya Liu
Keyword(s):  
Crustal Deformation ◽  
Ambient Noise ◽  
Southern California ◽  
Adjoint Tomography ◽  
Radial Anisotropy

Refined crustal and uppermost mantle structure of southern California by ambient noise adjoint tomography

2018 ◽  
Vol 215 (2) ◽  
pp. 844-863 ◽  
Author(s):  
Kai Wang ◽  
Yingjie Yang ◽  
Piero Basini ◽  
Ping Tong ◽  
Carl Tape ◽  
...  
Keyword(s):  
Ambient Noise ◽  
Southern California ◽  
Mantle Structure ◽  
Uppermost Mantle ◽  
Adjoint Tomography

scholarly journals Radial anisotropy and S-wave velocity depict the internal to external zones transition within the Variscan orogen (NW Iberia) 

2021 ◽  
Author(s):  
Jorge Acevedo ◽  
Gabriela Fernández-Viejo ◽  
Sergio Llana-Fúnez ◽  
Carlos López-Fernández ◽  
Javier Olona ◽  
...  
Keyword(s):  
Shear Wave ◽  
Wave Velocity ◽  
Ambient Noise ◽  
Variscan Orogeny ◽  
Low Grade ◽  
The West ◽  
Cantabrian Zone ◽  
Variscan Orogen ◽  
Nw Iberia ◽  
Radial Anisotropy

Abstract. The cross-correlation of ambient noise records registered by seismic networks has proven to be a valuable tool to obtain new insights into the crustal structure at different scales. Based on 2- to 14-s-period Rayleigh and Love dispersion data extracted from the seismic ambient noise recorded by 20 three-component broadband stations belonging to two different temporary experiments, we present the first i) upper crustal (1–14 km) high-resolution shear wave velocity and ii) radial anisotropy variation models of the continental crust in NW Iberia. The area of study represents one of the best exposed cross-sections along the Variscan orogen of western Europe, showing the transition between the external eastern zones towards the internal areas in the west. Both the 2-D maps and an E-W transect reveal a close correspondence with the main geological domains of the Variscan orogen. The foreland-fold and thrust-belt of the orogen, the Cantabrian Zone, is revealed by a zone of relatively low shear wave velocities (2.3–3.0 km/s), while the internal zones generally display higher homogeneous velocities (> 3.1 km/s). The boundary between both zones is clearly delineated in the models, depicting the arcuate shape of the orogen grain. The velocity patterns also reveal variations of the bulk properties of the rocks that can be linked to major Variscan structures, such as the basal detachment of the Cantabrian Zone or the stack of nappes involving pre-Variscan basement; or sedimentary features such as the presence of thick syn-orogenic siliciclastic wedges. Overall, the radial anisotropy magnitude varies between −5 and 15 % and increases with depth. The depth pattern suggests that the alignment of cracks is the main source of anisotropy at < 8 km depths, although the intrinsic anisotropy seems to be significant in the West-Asturian Leonese Zone, the low-grade slate belt adjacent to the Cantabrian Zone. At depths > 8 km, widespread high and positive radial anisotropies are observed, caused by the presence of subhorizontal alignments of grains and minerals in relation to the internal deformation of rocks either during the Variscan orogeny or prior to it.

scholarly journals One Year of Daily Satellite Orbit and Polar Motion Estimation for Near Real Time Crustal Deformation Monitoring

1993 ◽  
Vol 156 ◽  
pp. 279-284
Author(s):  
Yehuda Bock ◽  
Jie Zhang ◽  
Peng Fang ◽  
Joachim Genrich ◽  
Keith Stark ◽  
...  
Keyword(s):  
Real Time ◽  
Crustal Deformation ◽  
Polar Motion ◽  
Southern California ◽  
Regional Scale ◽  
Satellite Orbit ◽  
Pole Position ◽  
Terrestrial Reference Frame ◽  
Deformation Monitoring ◽  
Worst Case

The Permanent GPS Geodetic Array (PGGA) in southern California consists of five continuously operating stations established to monitor crustal deformation in near real time. The near real time requirement has been problematic since GPS satellite ephemerides and predicted earth orientation values (IERS Bulletins A and B) have been found to be neither sufficiently timely nor accurate to achieve horizontal position accuracies of several mm on regional scales. Therefore, we have been estimating precise GPS ephemerides and polar motion since August 1991. An examination of overlapping 24-hour satellite arcs indicates worst-case orbital errors of approximately 0.2 meters in the radial components, 1 meter in the cross-track components and 2–3 meters in the along-track components. A comparison with very long baseline interferometry indicates an accuracy of less than 1 mas in our determination of 24-hour values of pole position. These products are sufficiently timely and accurate to achieve several mm long-term horizontal precision in regional scale measurements of crustal deformation in near real time, as has been demonstrated during the 28 June, 1992 Landers and Big Bear earthquakes in southern California. The PGGA stations were able to detect seismically induced, sub-centimeter-level motions with respect to a terrestrial reference frame defined by the global tracking stations.

An Adjoint Technique for Estimation of Interstation Phase and Group Dispersion from Ambient Noise Cross Correlations

2019 ◽  
Vol 109 (5) ◽  
pp. 1716-1728
Author(s):  
Rhys Hawkins ◽  
Malcolm Sambridge
Keyword(s):  
Ambient Noise ◽  
Signal To Noise Ratio ◽  
Spectral Element ◽  
Second Step ◽  
Earth Model ◽  
Rayleigh Surface Waves ◽  
Radial Anisotropy ◽  
Cross Correlations ◽  
Noise Correlation Function ◽  
Tomographic Inversions

Abstract A method of extracting group and phase velocity dispersions jointly for Love‐ and Rayleigh‐wave observations is presented. This method uses a spectral element representation of a path average Earth model parameterized with density, shear‐wave velocity, radial anisotropy, and VP/VS ratio. An initial dispersion curve is automatically estimated using a heuristic approach to prevent misidentification of the phase. A second step then more accurately fits the observed noise correlation function (NCF) between interstation pairs in the frequency domain. For good quality cross correlations with reasonable signal‐to‐noise ratio, we are able to very accurately fit the spectrum of NCFs and hence obtain reliable estimates of both phase and group velocity jointly for Love and Rayleigh surface waves. In addition, we also show how uncertainties can be estimated with linearized approximations from the Jacobians and subsequently used in tomographic inversions.

Radial anisotropy in Valhall: ambient noise-based studies of Scholte and Love waves

2016 ◽  
Vol 208 (3) ◽  
pp. 1524-1539 ◽  
Author(s):  
Gaurav Tomar ◽  
Nikolai M. Shapiro ◽  
Aurelien Mordret ◽  
Satish C. Singh ◽  
Jean-Paul Montagner
Keyword(s):  
Ambient Noise ◽  
Love Waves ◽  
Radial Anisotropy

Crustal deformation measured in Southern California

Eos ◽  
1997 ◽  
Vol 78 (43) ◽  
pp. 477 ◽  
Author(s):  
Zheng-kang Shen ◽  
Danan Dong ◽  
Thomas Herring ◽  
Kenneth Hudnut ◽  
David Jackson ◽  
...  
Keyword(s):  
Crustal Deformation ◽  
Southern California

Present-day crustal deformation in southern California

1994 ◽  
Vol 99 (B12) ◽  
pp. 23951-23974 ◽  
Author(s):  
Hadley O. Johnson ◽  
Duncan Carr Agnew ◽  
Frank K. Wyatt
Keyword(s):  
Crustal Deformation ◽  
Southern California

scholarly journals Radial anisotropy in the crust of SE Tibet and SW China from ambient noise interferometry

2010 ◽  
Vol 37 (21) ◽  
pp. n/a-n/a ◽  
Author(s):  
Hui Huang ◽  
Huajian Yao ◽  
Robert D. van der Hilst
Keyword(s):  
Ambient Noise ◽  
Sw China ◽  
Noise Interferometry ◽  
Radial Anisotropy ◽  
Se Tibet

scholarly journals Comment on “Crustal deformation measured in Southern California”

Eos ◽  
1998 ◽  
Vol 79 (22) ◽  
pp. 260-260
Author(s):  
Paul A. Rydelek ◽  
I. Selwyn Sacks
Keyword(s):  
Crustal Deformation ◽  
Southern California
Sign in / Sign up

Export Citation Format

Share Document