Multiscale spatial distribution of crustal seismic anisotropy beneath the northeastern margin of the Tibetan plateau and tectonic implications of the Haiyuan fault

The Tibetan Plateau(TP) is known as ‘the water tower of Asian’, its precipitation variation play an important role in the eco-hydrological processes and water resources regimes. based on the monthly mean precipitation data of 65 meteorological stations over the Tibetan Plateau and the surrounding areas from 1961-2015,variations, trends and temporal-spatial distribution were analyzed, furthermore, the possible reasons were also discussed preliminarily. The main results are summarized as follows: the annual mean precipitation in the TP is 465.54mm during 1961-2015, among four seasons, the precipitation in summer accounts for 60.1% of the annual precipitation, the precipitation in summer half year (May.- Oct.) accounts for 91.0% while that in winter half year (Nov.- Apr.) only accounts for 9.0%; During 1961-2015, the annual precipitation variability is 0.45mm/a and the seasonal precipitation variability is 0.31mm/a, 0.13mm/a, -0.04mm/a and 0.04mm/a in spring, summer, autumn and winter respectively on the TP; The spatial distribution of precipitation can be summarized as decreasing from southeast to northwest in the TP, the trend of precipitation is decreasing with the increase of altitude, but the correlation is not significant. The rising of air temperature and land cover changes may cause the precipitation by changing the hydrologic cycle and energy budget, furthermore, different pattern of atmospheric circulation can also influence on precipitation variability in different regions.

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A time-domain inversion technique for the tempo-spatial distribution of slip on a finite fault plane with applications to recent large earthquakes in the Tibetan Plateau

Geophysical Journal International ◽

10.1046/j.1365-246x.2000.01263.x ◽

2000 ◽

Vol 143 (2) ◽

pp. 407-416 ◽

Cited By ~ 17

Author(s):

Y. T. Chen ◽

L. S. Xu

Keyword(s):

Spatial Distribution ◽

Tibetan Plateau ◽

Time Domain ◽

Fault Plane ◽

The Tibetan Plateau ◽

Inversion Technique ◽

Finite Fault ◽

Domain Inversion ◽

Large Earthquakes

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Deformation and sedimentary responses to top‐to‐north shear along the range front of the Big Bend of the Ailao Shan–Red River shear zone, SE edge of the Tibetan Plateau, and its tectonic implications

Tectonics ◽

10.1029/2021tc007067 ◽

2021 ◽

Author(s):

E.C. Wang ◽

C. Fan ◽

Z. Su

Keyword(s):

Tibetan Plateau ◽

Shear Zone ◽

Red River ◽

The Tibetan Plateau ◽

Big Bend ◽

Tectonic Implications

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Multilayered Crustal Anisotropy in Eastern Tibet Revealed by Receiver Function Data

10.5194/egusphere-egu2020-7623 ◽

2020 ◽

Author(s):

Shaohua Qi ◽

Qiyuan Liu ◽

Jiuhui Chen ◽

Biao Guo

Keyword(s):

Tibetan Plateau ◽

Lower Crust ◽

Seismic Anisotropy ◽

Receiver Function ◽

Azimuthal Anisotropy ◽

Strain History ◽

The Tibetan Plateau ◽

Anisotropy Axis ◽

Upper Crust ◽

Western Sichuan

It is widely accepted that the ongoing India-Asia collision since approximately 50 Ma ago has resulted in the uplift and eastward expansion of the Tibetan Plateau. Yet the interpretations of its dynamic process and deformation mechanism still remain controversial. Distinct models that emphasize particular aspects of the tectonic features have been proposed, including fault-controlled rigid blocks, continuous deformation of lithosphere and lower crust flow.One possible way to reconcile these models is to investigate crustal deformation at multiple depths simultaneously, as well as crust-mantle interaction. Seismic anisotropy is considered as an effective tool to study the geometry and distribution of subsurface deformation, due to its direct connection to the stress state and strain history of anisotropic structures and fabrics. In the eastern margin of Tibetan plateau, previous studies of seismic anisotropy have already provided useful insights into the bulk anisotropic properties of the entire crust or upper mantle, based on shear wave splitting analyses of Moho Ps and XKS phases.In this study, we went further to extract anisotropic parameters of multiple crustal layers by waveform inversion of teleseismic receiver function (RF) data from the western-Sichuan temporal seismic array using particle swarm optimization. Instead of directly fitting the backazimuthal stacking of RFs from each station, we translated the RF data into backazimuthal harmonic coefficients using harmonic decomposition technique, which separates the signals (of planar isotropic structure and anisotropy) from the scattering noise generated by non-planar lateral heterogeneity. The constant (k=0) and k=1, 2 terms of backazimuthal harmonic coefficients were used in our inversion. We also fixed the anisotropic model to slow-axis symmetry to avoid ambiguous interpretations.Our results show that:(1) Anisotropy with a titled anisotropy axis of symmetry is more commonly observed than pure azimuthal anisotropy in our data, which has been also reported by other RF studies across the surrounding areas of Tibetan plateau.(2) The trends of slow symmetry axis vary from the upper to lower part of the crust in both Chuandian and Songpan units, indicating the deformation of the upper crust is decoupled from that of the lower crust in these two regions, while the trends are more consistent throughout the crust in the Sichuan basin.(3) In the upper crust, the trends show a degree of tendency to lie parallel to the major geological features such as the Xianshuihe and Longmenshan faults, exhibiting a fault-controlled deformation or movement. In the middle and lower crust, the trends are NS or NW-SE in Chuandian unit and NE-SW in Songpan unit, which are coincident with the apparent extension directions of the ductile crustal flow.

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