Estimation of shear‐wave splitting time using orthogonal transformation

Geophysics ◽  
1997 ◽  
Vol 62 (2) ◽  
pp. 657-661 ◽  
Author(s):  
Chiou‐Fen Shieh
Keyword(s):  
Oil Shale ◽  
Seismic Anisotropy ◽  
Orthogonal Transformation ◽  
Laboratory Studies ◽  
The Earth ◽  
Wave Splitting ◽  
Mineral Assemblages ◽  
Long Time ◽  
Anisotropic Elastic ◽  
Splitting Time

Laboratory studies of rock samples show that many mineral assemblages exhibit anisotropic elastic properties. Additionally, it has been known for a long time that stacked isotropic layers exhibit the same properties (Thomson, 1950; Thomsen, 1986). Oil shale, for example, presents such anisotropy. There's no doubt, then, that seismic anisotropy can be considered a promising method of studying the interior of the Earth (Babuska and Cara, 1991).

scholarly journals Large-scale variation in seismic anisotropy in the crust and upper mantle beneath Anatolia, Turkey

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Cédric P. Legendre ◽  
Li Zhao ◽  
Tai-Lin Tseng
Keyword(s):  
Upper Mantle ◽  
Large Scale ◽  
Seismic Anisotropy ◽  
Crust And Upper Mantle ◽  
Wave Splitting ◽  
Mantle Processes ◽  
Open Question ◽  
Subduction System ◽  
Anisotropic Phase ◽  
Regional Tectonics

AbstractThe average anisotropy beneath Anatolia is very strong and is well constrained by shear-wave splitting measurements. However, the vertical layering of anisotropy and the contribution of each layer to the overall pattern is still an open question. Here, we construct anisotropic phase-velocity maps of fundamental-mode Rayleigh waves for the Anatolia region using ambient noise seismology and records from several regional seismic stations. We find that the anisotropy patterns in the crust, lithosphere and asthenosphere beneath Anatolia have limited amplitudes and are generally consistent with regional tectonics and mantle processes dominated by the collision between Eurasia and Arabia and the Aegean/Anatolian subduction system. The anisotropy of these layers in the crust and upper mantle are, however, not consistent with the strong average anisotropy measured in this area. We therefore suggest that the main contribution to overall anisotropy likely originates from a deep and highly anisotropic region round the mantle transition zone.

Seismic anisotropy and mantle flow constrained by shear wave splitting in central Myanmar

2021 ◽  
Author(s):  
Enbo Fan ◽  
Yumei He ◽  
Yinshuang Ai ◽  
Stephen S. Gao ◽  
Kelly H. Liu ◽  
...  
Keyword(s):  
Shear Wave ◽  
Seismic Anisotropy ◽  
Shear Wave Splitting ◽  
Mantle Flow ◽  
Wave Splitting

Gravimetric Method for Calibrating Flow Meter

2014 ◽  
Vol 501-504 ◽  
pp. 2335-2337
Author(s):  
Xi Ming Zhang ◽  
Xue Li
Keyword(s):  
Solar Energy ◽  
Gravimetric Method ◽  
Correction Coefficient ◽  
Flow Meter ◽  
The Earth ◽  
Improve Measurement ◽  
Long Time ◽  
Experimental Errors ◽  
Lower Energy Density ◽  
Test Use

What the earth obtain the energy annually is ten thousand times of the earth energy consumption at present,but the solar energy has a lower energy density on the earth’s surface .solar energy is the main source of all energy The experimental research was conducted for the heating performance utilizing the solar-assisted heat pump experimental platform. Experimental errors will be caused to flow meter by different measured media and long time usage In order to improve measurement precision and reduce the experimental errors, this test use gravimetric method to calibrate the LZB glass rotor meter and MCE08-787 cumulative flow meter of indoors and outdoors pipes. The paper also presents flow correction coefficient to guarantee both the accuracy and reliability of the experimental results.

Seismic anisotropy of the crust and upper mantle beneath western Tibet revealed by shear wave splitting measurements

2018 ◽  
Vol 216 (1) ◽  
pp. 535-544 ◽  
Author(s):  
Changhui Ju ◽  
Junmeng Zhao ◽  
Ning Huang ◽  
Qiang Xu ◽  
Hongbing Liu
Keyword(s):  
Shear Wave ◽  
Upper Mantle ◽  
Seismic Anisotropy ◽  
Shear Wave Splitting ◽  
Crust And Upper Mantle ◽  
Wave Splitting

scholarly journals The Excess Secular Change in the Obliquity of the Ecliptic and Its Relation to the Internal Motion of the Earth

1972 ◽  
Vol 48 ◽  
pp. 192-195 ◽  
Author(s):  
Chuichi Kakuta ◽  
Shinko Aoki
Keyword(s):  
Time Variation ◽  
Rotational Speed ◽  
Internal Motion ◽  
Secular Change ◽  
Electrically Conducting ◽  
The Core ◽  
The Earth ◽  
Fluid Core ◽  
Electrical Conductivities ◽  
Long Time

The previous result (Aoki, 1969) on the explanation of the excess secular change in the obliquity of the ecliptic frictional couplings in the rigid constituents, the mantle and the core, is extended by using a model of an elastic and electrically conducting mantle and a hydromagnetic core. The secular change of the obliquity of the ecliptic referred to the mantle is found to be 1/3.2 times of the observed value, if the electrical conductivities of the fluid core and the mantle are assumed to be 3·10−6 emu and 3·10−9 emu respectively. A large secular deceleration of the Earth's rotational speed obtained in the previous result is proved to be strongly reduced because of weak excitation of the perturbing potential for a long time variation.

scholarly journals DAKWAH DAN MASALAH KONTEMPORER

2018 ◽  
Vol 1 (1) ◽  
pp. 44
Author(s):  
Syafriwaldi Syafriwaldi
Keyword(s):  
Work Ethic ◽  
Science And Technology ◽  
Religious Ritual ◽  
The Earth ◽  
Long Time ◽  
Vertical Relationship ◽  
The Subject ◽  
Economic Improvement

In the science and technology currently, also the success development have penetrated all aspects of the field of life, it is not only bringing the convenience and happiness, but also to new behaviors and issues. There are many issues that long time ago was never known, never imagined; now they are true. this reality is meant by contemporary issues. During this time the theme and scope of da'wah only revolves around the problems of hablum minallah (vertical relationship), or in akhhrawi problem; Syahadat, prayer, fasting, hajj and other religious ritual themes. While the theme of other Islamic da'wah, namely hablum minannas (horizontal relationship) is not much touched on, when in fact the scope or theme of da'wah is very broad. Issues of the ummah's interests are part of the themes of Islamic da'wah, such as democracy, the problem of increasing the resources of the ummah, the problem of economic improvement, work ethic and others. They are rarely alluded in the subject of da'wah material so that da'wah seems not to stand on the earth but in the air.

scholarly journals Measuring Crustal Seismic Anisotropy through Shear Wave Splitting

2021 ◽  
Author(s):  
◽  
Kenny Graham
Keyword(s):  
Numerical Simulation ◽  
New Zealand ◽  
Shear Wave ◽  
Seismic Anisotropy ◽  
Shear Wave Splitting ◽  
Anisotropic Structure ◽  
Crustal Anisotropy ◽  
Physical Mechanisms ◽  
Alpine Fault ◽  
Wave Splitting

<p>This thesis involves the study of crustal seismic anisotropy through shear wave splitting. For the past three decades, shear wave splitting (SWS) measurements from crustal earthquakes have been utilized as a technique to characterize seismic anisotropic structures and to infer in situ crustal properties such as the state of the stress and fracture geometry and density. However, the potential of this technique is yet to be realized in part because measurements on local earthquakes are often controlled and/or affected by physical mechanisms and processes which lead to variations in measurements and make interpretation difficult. Many studies have suggested a variety of physical mechanisms that control and/or affect SWS measurements, but few studies have quantitatively tested these suggestions. This thesis seeks to fill this gap by investigating what controls crustal shear-wave splitting (SWS) measurements using empirical and numerical simulation approaches, with the ultimate aim of improving SWS interpretation. For our empirical approach, we used two case studies to investigate what physical processes control seismic anisotropy in the crust at different scales and tectonic settings. In the numerical simulation test, we simulate the propagation of seismic waves in a variety of scenarios.  We begin by measuring crustal anisotropy via SWS analysis around central New Zealand, where clusters of closely-spaced earthquakes have occurred. We used over 40,000 crustal earthquakes across 36 stations spanning close to 5.5 years between 2013 and 2018 to generate the largest catalog of high-quality SWS measurements (~102,000) around the Marlborough and Wellington region. The size of our SWS catalog allowed us to perform a detailed systematic analysis to investigate the processes that control crustal anisotropy and we also investigated the spatial and temporal variation of the anisotropic structure around the region. We observed a significant spatial variation of SWS measurements in Central New Zealand. We found that the crustal anisotropy around Central New Zealand is confined to the upper few kilometers of the crust, and is controlled by either one mechanism or a combination of more than one (such as structural, tectonic stresses, and gravitational stresses). The high correspondence between the orientation of the maximum horizontal compressive stress calculated from gravitational potential energy from topography and average fast polarization orientation around the Kaikōura region suggests that gravitationally induced stresses control the crustal anisotropy in the Kaikōura region. We suggest that examining the effect of gravitational stresses on crustal seismic anisotropy should not be neglected in future studies. We also observed no significant temporal changes in the state of anisotropy over the 5.5 year period despite the occurrence of significant seismicity.   For the second empirical study, we characterized the anisotropic structure of a fault approaching failure (the Alpine Fault of New Zealand). We performed detailed SWS analysis on local earthquakes that were recorded on a dense array of 159 three-component seismometers with inter-station spacing about 30 m around the Whataroa Valley, New Zealand. The SWS analysis of data from this dense deployment enabled us to map the spatial characteristics of the anisotropic structure and also to investigate the mechanisms that control anisotropy in the Whataroa valley in the vicinity of the Alpine Fault. We observed that the orientation of the fast direction is parallel to the strike of the Alpine Fault trace and the orientations of the regional and borehole foliation planes. We also observed that there was no significant spatial variation of the anisotropic structure as we move across the Alpine Fault trace from the hanging wall to the footwall. We inferred that the geological structures, such as the Alpine Fault fabric and foliations within the valley, are the main mechanisms that control the anisotropic structure in the Whataroa valley.    For our numerical simulation approach, we simulate waveforms propagating through an anisotropic media (using both 1-D and 3-D techniques). We simulate a variety of scenarios, to investigate how some of the suggested physical mechanisms affect SWS measurements. We considered (1) the effect on seismic waves caused by scatterers along the waves' propagation path, (2) the effect of the earthquake source mechanism, (3) the effect of incidence angle of the incoming shear wave. We observed that some of these mechanisms (such as the incidence angle of the incoming shear wave and scatterers) significantly affect SWS measurement while others such as earthquake source mechanisms have less effect on SWS measurements. We also observed that the effect of most of these physical mechanisms depends on the wavelength of the propagating shear wave relative to the size of the features. There is a significant effect on SWS measurements if the size of the physical mechanism (such as scatterers) is comparable to the wavelength of the incoming shear wave. With a larger wavelength, the wave treats the feature as a homogeneous medium.</p>

scholarly journals Supplemental Material: Seismic anisotropy in southern Costa Rica confirms upper mantle flow from the Pacific to the Caribbean

2020 ◽  
Author(s):  
Vadim Levin ◽  
et al.
Keyword(s):  
Data Analysis ◽  
Costa Rica ◽  
Upper Mantle ◽  
Seismic Anisotropy ◽  
Data Sources ◽  
Mantle Flow ◽  
Analysis Methodology ◽  
The Pacific ◽  
Wave Splitting ◽  
The Caribbean

Data sources, details of data analysis methodology, and additional diagrams and maps of shear wave splitting measurements.<br>

scholarly journals Seismic anisotropy and shear wave splitting associated with mantle plume-plate interaction

2014 ◽  
Vol 119 (6) ◽  
pp. 4923-4937 ◽  
Author(s):  
Garrett Ito ◽  
Robert Dunn ◽  
Aibing Li ◽  
Cecily J. Wolfe ◽  
Alejandro Gallego ◽  
...  
Keyword(s):  
Shear Wave ◽  
Mantle Plume ◽  
Seismic Anisotropy ◽  
Shear Wave Splitting ◽  
Wave Splitting
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