Shallow Crustal Structure of the Middle‐Lower Yangtze River Region in Eastern China from Surface‐Wave Tomography of a Large Volume Airgun‐Shot Experiment

2018 ◽  
Vol 89 (3) ◽  
pp. 1003-1013 ◽  
Author(s):  
Yuyang She ◽  
Huajian Yao ◽  
Qiushi Zhai ◽  
Fuyun Wang ◽  
Xiaofeng Tian
Keyword(s):  
Surface Wave ◽  
Crustal Structure ◽  
Large Volume ◽  
Yangtze River ◽  
Eastern China ◽  
Surface Wave Tomography ◽  
River Region ◽  
Wave Tomography ◽  
Lower Yangtze

scholarly journals Surface wave tomography across Afar, Ethiopia: Crustal structure at a rift triple-junction zone

2011 ◽  
Vol 38 (24) ◽  
pp. n/a-n/a ◽  
Author(s):  
M. Guidarelli ◽  
G. Stuart ◽  
J. O. S. Hammond ◽  
J. M. Kendall ◽  
A. Ayele ◽  
...  
Keyword(s):  
Surface Wave ◽  
Crustal Structure ◽  
Triple Junction ◽  
Junction Zone ◽  
Surface Wave Tomography ◽  
Wave Tomography

Direct inversion of surface wave dispersion data with multiple-grid parameterizations and its application to a dense array in Chao Lake, eastern China

2021 ◽  
Author(s):  
Song Luo ◽  
Huajian Yao ◽  
Jiannan Wang ◽  
Kangdong Wang ◽  
Bin Liu
Keyword(s):  
Surface Wave ◽  
Eastern China ◽  
Surface Wave Tomography ◽  
Low Velocity ◽  
Direct Inversion ◽  
Tanlu Fault ◽  
Wave Tomography ◽  
Velocity Anomalies ◽  
Multiple Grids ◽  
Collocated Grids

Summary The direct surface wave tomography has become an efficient tool in imaging three-dimensional (3-D) shallow Earth structure. However, some fundamental problems still exist in selecting the grids to parameterize the model space. This study proposes to implement a model parameterization approach with multiple grids to the direct surface wave tomography. These multiple grids represent several overlapping collocated grids with the same or different grid spacings, such as staggered grids, multiscale grids, and multiscale-staggered grids. At each iteration, direct inversion is applied to each individual set of collocated grids to invert for the shear-wave velocity (Vs) model; the models are then projected onto a set of predefined base grids (usually the finest grids) using 3-D B-spline interpolation. At the end of each iteration, we average the Vs models of all sets of collocated grids to obtain the average 3-D Vs model, which is then used as the initial model for the next iteration. The properties of this approach are explored by applying it to a newly deployed dense array in Chao Lake (CL), eastern China. Synthetic and field data tests demonstrate that the method using multiple grids recovers anomaly patterns better than that using the individual set of collocated grids, though it does not necessarily achieve the smallest traveltime residual. We then obtain a high-resolution 3-D shallow crustal Vs model beneath the CL. The 3-D Vs model reveals two prominent features: (1) a stripe-like structural pattern of velocity variations, where the Hefei basin and eastern CL display low-velocity anomalies while the Tanlu fault zone (TFZ), Zhangbaling uplift, and Yinping mountain present high-velocity anomalies; (2) north-shifted low-velocity anomalies beneath the eastern CL as depths go shallow. The shallow Vs features are consistent well with the local geological units and topography. We suggest that the two main features could be associated with the multistage tectonic activities of the Tanlu fault. The multiple-grid scheme proposed in this study could be conveniently extended to other 3-D direct inversion approaches in the near future.

scholarly journals The lithosphere-asthenosphere boundary observed with USArray receiver functions

2012 ◽  
Vol 4 (1) ◽  
pp. 1-31 ◽  
Author(s):  
P. Kumar ◽  
X. Yuan ◽  
R. Kind ◽  
J. Mechie
Keyword(s):  
Surface Wave ◽  
Receiver Function ◽  
The United States ◽  
Receiver Functions ◽  
Function Technique ◽  
Surface Wave Tomography ◽  
Entire Area ◽  
S Receiver Function ◽  
The Usa ◽  
Wave Tomography

Abstract. The dense deployment of seismic stations so far in the western half of the United States within the USArray project provides the opportunity to study in greater detail the structure of the lithosphere-asthenosphere system. We use the S receiver function technique for this purpose which has higher resolution than surface wave tomography, is sensitive to seismic discontinuities and has no problems with multiples like P receiver functions. Only two major discontinuities are observed in the entire area down to about 300 km depth. These are the crust-mantle boundary (Moho) and a negative boundary which we correlate with the lithosphere-asthenosphere boundary (LAB) since a low velocity zone is the classical definition of the seismic observation of the asthenosphere by Gutenberg (1926). Our S receiver function LAB is at a depth of 70–80 km in large parts of westernmost North America. East of the Rocky Mountains its depth is generally between 90 and 110 km. Regions with LAB depths down to about 140 km occur in a stretch from northern Texas over the Colorado Plateau to the Columbia Basalts. These observations agree well with tomography results in the westernmost USA and at the east coast. However, in the central cratonic part of the USA the tomography LAB is near 200 km depth. At this depth no discontinuity is seen in the S receiver functions. The negative signal near 100 km depth in the central part of the USA is interpreted by Yuan and Romanowicz (2010) or Lekic and Romanowicz (2011) as a recently discovered mid lithospheric discontinuity (MLD). A solution for the discrepancy between receiver function imaging and surface wave tomography is not yet obvious and requires more high resolution studies at other cratons before a general solution may be found. Our results agree well with petrophysical models of increased water content in the asthenosphere, which predict a sharp and shallow LAB also in continents (Mierdel et al., 2007).

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