Shear Wave Splitting and the Features of the Crustal Stress Field in the Capital Circle

2006 ◽  
Vol 49 (1) ◽  
pp. 157-166 ◽  
Author(s):  
Yuan-Gen LAI ◽  
Qi-Yuan LIU ◽  
Jiu-Hui CHEN ◽  
Jie LIU ◽  
Shun-Cheng LI ◽  
...  
Keyword(s):  
Stress Field ◽  
Shear Wave ◽  
Shear Wave Splitting ◽  
Crustal Stress ◽  
Wave Splitting ◽  
Crustal Stress Field

Features of the Shear Wave Splitting and Stress Field in the Xinjiang-Jiashi Strong Earthquake Region

2002 ◽  
Vol 45 (1) ◽  
pp. 78-86 ◽  
Author(s):  
Yuan-Gen LAI ◽  
Qi-Yuan LIU ◽  
Jiu-Hui CHEN ◽  
Biao GUO ◽  
Shun-Cheng LI
Keyword(s):  
Stress Field ◽  
Shear Wave ◽  
Strong Earthquake ◽  
Shear Wave Splitting ◽  
Wave Splitting

An upper crust shear-wave splitting study for the period 2013-2014 in the Western Gulf of Corinth (Greece)

2021 ◽  
Author(s):  
George Kaviris ◽  
Vasilis Kapetanidis ◽  
Georgios Michas ◽  
Filippos Vallianatos
Keyword(s):  
Stress Field ◽  
Shear Wave ◽  
Shear Wave Splitting ◽  
Double Difference ◽  
Extension Rate ◽  
Upper Crust ◽  
Inspection Method ◽  
Gulf Of Corinth ◽  
Waveform Cross Correlation ◽  
Wave Splitting

<p>Seismic anisotropy is investigated by performing an upper crust shear-wave splitting study in the Western Gulf of Corinth (WGoC). The study area, which is a tectonic rift located in Central Greece, is one of the most seismically active regions in Europe, characterized by a 10 to 15 mm/year extension rate in a NNW-SSE direction and E-W normal faulting. Intense seismic activity has been recorded in the WGoC during 2013-2014, including the 2013 Helike swarm, at the southern coast, and the offshore 2014 seismic sequence between Nafpaktos and Psathopyrgos, including an Mw 4.9 event on 21 September 2014. The largest event of the study period was an Mw 5.0 earthquake that occurred in November 2014, offshore Aigion, followed by an aftershock sequence. Seismicity was relocated using the double-difference method, including waveform cross-correlation differential travel-time data, yielding a high-resolution earthquake catalogue of approximately 9000 local events. This dataset was utilized in order to determine the shear-wave splitting parameters in seven stations installed at the WGoC, using a fully automatic technique based on the eigenvalue method and cluster analysis. A smaller subset was analyzed with the visual inspection method (polarigrams and hodograms) for verification of the automatic measurements. All selected station-event pairs were within the shear-wave window and had adequately high signal-to-noise ratio. The orientation of the seismometers of all stations used in the present study has been measured and verified in order to ensure the validity of the obtained fast shear-wave polarization directions and to apply corrections for borehole instruments. Mean anisotropy directions are in general agreement with the horizontal component of the dominant stress field, with some deviations, likely related to mapped faults and local stress anomalies. Temporal variations of time-delays between the two split shear-waves are examined in order to investigate their connection to possible stress field variations, related either to the occurrence of moderate to strong events or to fluid migration.</p><p>Acknowledgements</p><p>We would like to thank the personnel of the Hellenic Unified Seismological Network (http://eida.gein.noa.gr/) and the Corinth Rift Laboratory Network (https://doi.org/10.15778/RESIF.CL) for the installation and operation of the stations used in the current article. The present research is co-financed by Greece and the European Union (European Social Fund- ESF) through the Operational Programme «Human Resources Development, Education and Lifelong Learning 2014-2020» in the context of the project “The role of fluids in the seismicity of the Western Gulf of Corinth (Greece)” (MIS 5048127).</p>

Spatially Distinct Tectonic Zones across Oklahoma Inferred from Shear-Wave Splitting

2021 ◽  
Author(s):  
Angie D. Ortega-Romo ◽  
Jacob I. Walter ◽  
Xiaowei Chen ◽  
Brett M. Carpenter
Keyword(s):  
Stress Field ◽  
Shear Wave ◽  
Structural Control ◽  
Horizontal Stress ◽  
Shear Wave Splitting ◽  
Wave Splitting ◽  
Stress Orientations ◽  
Maximum Horizontal Stress ◽  
Direction Of Polarization ◽  
Fast Polarization

Abstract To better understand relationships among crustal anisotropy, fracture orientations, and the stress field in Oklahoma and southern Kansas, we conduct shear-wave splitting analysis on the last 9 yr of data (2010–2019) of local earthquake observations. Rather than a predominant fast direction (ϕ), we find that most stations have a primary fast direction of polarization (ϕpri) and a secondary fast direction of polarization (ϕsec). At most stations, either the primary fast direction of polarization (ϕpri) or the secondary fast direction of polarization (ϕsec) is consistent with the closest estimated maximum horizontal stress (σHmax) orientation in the vicinity of the observation. The general agreement between fast directions of polarization (ϕ) and the maximum horizontal stress orientations (σHmax) at the regional level implies that the fast polarization directions (ϕ) are extremely sensitive to the regional stress field. However, in some regions, such as the Fairview area in western Oklahoma, we observe discrepancies between fast polarization directions (ϕ) and maximum horizontal stress orientations (σHmax), in which the fast directions are more consistent with local fault structures. Overall, the primary fast direction of polarization (ϕpri) is mostly controlled and influenced by the stress field, and the secondary fast direction of polarization (ϕsec) likely has some geologic structural control because the secondary direction is qualitatively parallel to some mapped north-striking fault zones. No significant changes in fast directions over time were detected with this technique over the 5 yr (2013–2018) of measurements, suggesting that pore pressure may not cause a significant enough or detectable change above the magnitude of the background stress field.

scholarly journals Insight into NE Tibetan Plateau expansion from crustal and upper mantle anisotropy revealed by shear-wave splitting

2017 ◽  
Vol 478 ◽  
pp. 66-75 ◽  
Author(s):  
Zhouchuan Huang ◽  
Frederik Tilmann ◽  
Mingjie Xu ◽  
Liangshu Wang ◽  
Zhifeng Ding ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Shear Wave ◽  
Upper Mantle ◽  
Shear Wave Splitting ◽  
Upper Mantle Anisotropy ◽  
Wave Splitting ◽  
Mantle Anisotropy ◽  
Insight Into ◽  
Ne Tibetan Plateau
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