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Geophysics
November 2010 Vol.55 No.31: 3599–3605
doi: 10.1007/s11434-010-4135-y
SPECIAL TOPICS:
Crust-mantle coupling in North China: Preliminary analysis from
seismic anisotropy
GAO Yuan1*, WU Jing2, YI GuiXi3 & SHI YuTao1
1
Institute of Earthquake Science, China Earthquake Administration, Beijing 100036, China;
Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China;
3
Earthquake Administration of Sichuan Province, Chengdu 610041, China
2
Received May 4, 2010; accepted July 7, 2010
Data from the CASN (Capital Area Seismograph Network), NSNC (National Seismograph Network of China), and IRIS (Incorporated Research Institutions for Seismology) are compared with data from a temporary North China Seismic Array to obtain the
background orientation of the horizontal crustal principal compressive stress at NE 95.1°±15.4° in North China. Data are corrected for disturbances of faults and irregular tectonics, and are used to constrain the fast SKS polarization at NE 110.2°±15.8° in
North China. Individual station analyses suggests that there is consistently more than 10° difference between the polarizations of
fast shear-wave in the crust and those of fast SKS phases. Azimuthally anisotropic phase velocities of Rayleigh waves at different
periods also indicate an orientation change for fast velocity with depth. It suggests the crust-mantle coupling in North China follows neither the simple decoupling model nor the strong coupling model. Instead, it is possibly some inhomogeneous combination
of two models or some gradual-change model of physical characteristics. This study shows that anisotropy in the crust and mantle
could be multiply characterized more correctly and crust-mantle coupling could be analyzed further, if increasing near-field
shear-wave splitting data that indicate crustal anisotropy, combined with the azimuthal anisotropy of Rayleigh waves, besides the
result of SKS splitting travelling through lithosphere and surface GPS measurements.
seismic anisotropy, crust-mantle coupling, polarization direction of fast shear-wave, shear-wave splitting, crustal principal
compressive stress, North China
Citation:
Gao Y, Wu J, Yi G X, et al. Crust-mantle coupling in North China: Preliminary analysis from seismic anisotropy. Chinese Sci Bull, 2010, 55: 3599−3605,
doi: 10.1007/s11434-010-4135-y
Coupling between the crust and the mantle is related to deep
geophysical processes and geological movements, and is
also critically influenced by present plate movements that
can be expressed by geodynamic models. In terms of terrain
and geology, the North China, a specific zone named in
China, can be divided into three neo-tectonic units: (1) the
Yanshan uplift, (2) the Taihang uplift and (3) the North
China Basin. Late Pleistocene and Holocene tectonic processes are active in this area, one of the most active tectonic
zones on the Chinese mainland [1,2].
The surficial and deep geological characteristics of North
China are complex. The crustal thickness distribution in
*Corresponding author (email: [email protected])
© Science China Press and Springer-Verlag Berlin Heidelberg 2010
East Asia, determined from the inversion of controlledsource deep seismic sounding data, shows crustal thicknesses of 28–30 km beneath the Bohai Sea Basin, where the
Moho depth is 4 km deeper than in the surrounding areas.
The underlying complex tectonic framework and the deep
dynamic processes of East Asia suggest that fluctuations in
the Moho discontinuity result from such processes as the
collision and extrusion of the plate, differentiation and adjustment of deep material, and crustal heat exchange [3].
Tomographic and receiver function experiments have
shown that the crustal velocity has been affected by surficial
tectonics and major deep fracturing in the northern Bohai
Sea Basin and surrounding areas. Velocity anomalies are
predominantly distributed along NE-SW or NNE-SSW oricsb.scichina.com
www.springerlink.com
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GAO Yuan, et al.
Chinese Sci Bull
entations, with E-W oriented belt-shaped and N-S oriented
block-shaped characteristics. Uplift of the upper mantle was
also locally found within this area [4–7].
The wider cratonic region surrounding our study area in
North China has globally important tectonic features. In
general, because of low density, low temperature and a
thick lithospheric root, cratons are the most stable zones on
Earth. However, the North China Craton, composed of a
destroyed eastern block and a stable western block, shows
significant differences with other cratons elsewhere in the
world [8,9]. The main destruction mechanism of the North
China Craton might be chemical attack [10] or delamination
[8]. One of the main characteristics of the North China Craton is the thinning lithosphere. This thinning has been considered by some to be the result of subduction erosion [11].
Seismic anisotropy investigations of the upper mantle show
that the time-delays of SKS splitting in the North China
Basin are smaller than in the central and western parts of the
uplift in neighboring parts of North China [12–14]. This
evidence puts relative differences in lithosphere thickness in
perspective.
Seismic waves traveling though deep media provide important information on deep Earth structures. Whether the
crust and mantle decouple in North China is one of the key
factors in the study of the present-day deep dynamic configuration of eastern China. It is related to the establishment
of a deep movement model for eastern Asia. It is an effective method that uses seismic anisotropy to study crustmantle coupling relationships [15,16]. Seismic anisotropy in
the upper mantle can be related to deformation patterns of
deep lithospheric media and reflect the movement and surrounding stress patterns of deep media that reach down to
the upper mantle [14,17,18].
Research with low-frequency teleseismic data has constrained seismic anisotropy from SKS splitting analyses to
investigate crust-mantle coupling relationships [15]. However, the SKS method averages information over the entire
thickness of the lithosphere. To increase the relative information regarding the crust, it is important to discuss the
coupling between the crust and mantle, and also to precisely
define the nature of the crust and mantle.
Some seismic anisotropy studies from eastern China have
contrasted plate motion by examining reflection and refraction waves at various depth interfaces. However, preliminary conclusions are limited by data availability and their
reliability needs to be improved [19]. Crustal seismic anisotropy is related directly to stress-aligned grain-boundary
cracks in the crust, which in turn are essentially related to
crustal stresses [20–23]. Crustal seismic anisotropy can be
quantified by analyzing seismic waveform records of natural earthquakes [22,24,25], but also can be determined using
artificial sources [26,27]. However, in the vicinity of a highdensity seismic network that has been in continuous operation for several years, seismic records of natural earthquakes are the preferred choice.
November (2010) Vol.55 No.31
Seismic anisotropic features obtained from various data
sources and methods show different aspects of regional
seismic anisotropy [28]. For example, rather than comparing anisotropy from low-frequency teleseismic data with
surficial GPS strain measurements in crust-mantle coupling
investigation, it is apparently better to increase the weighting of anisotropic results that use near-field high-frequency
seismic data; further discussion is needed here. The combination of analyses of crustal and mantle anisotropy with
surficial GPS observations makes for an important advance
in crust-mantle coupling research.
1
Data and methods
There are five National Seismograph Network of China
(NSNC) stations in North China: Beijing, Taiyuan, Hongshan, Tai’an and Dalian stations. The NSNC Beijing station
is a short-period instrument, but broad-band records are
available from another Beijing station (BJT) belonging to
the Incorporated Research Institutions for Seismology
(IRIS) network under an international exchange relationship. As a result of the band requirements of this study, the
broad-band records from station BJT are adopted. BJT is an
STS-2 seismometer, whereas stations Taiyuan (TIY),
Hongshan (HNS) and Dalian (DL2) use CTS-1 seismometers and station Tai’an (TIA) uses a JCZ-1 seismometer; all
of these record broad-band signals or very broad-band signals. The frequency bands of these seismometers are respectively 120 s–40 Hz for STS-2, 120 s–50 Hz for CTS-1,
360 s–20 Hz for JCZ-1. In this study, these five stations are
used to collect teleseismic broad-band records for the seismic events with magnitudes larger than or equal to 5.8 and
epicentral distances greater than 85°. The continuous records for the four NSNC stations cover 5 years whereas BJT
covers 10 years from 1995 to 2004. Eligible records containing clear SKS phases were used to calculate seismic
anisotropy parameters.
At present there are two main methods to calculate SKS
splitting: the Vinnik method [17] and the Silver and Chan
[18] (SC) method. In this region, SKS splitting results at
BJT were obtained first by the Vinnik method [12]. Later,
with more data, a study using the SC method obtained parameters of SKS splitting at BJT with results that are fully
consistent with the Vinnik method [14] and also consistent
with other independent studies [13,29,30]. The SC method
has now been widely adopted globally to calculate SKS
splitting. This study also uses the SC method to analyze
more data and thereby to enhance the reliability of results.
The calculation methods, data selection, classification and
analysis techniques applied here are in accordance with Liu
et al. [14]; more details and examples can be found elsewhere [31,32].
Calculations of crustal anisotropy in this study apply the
Systematic Analysis Method (SAM), a comprehensive
GAO Yuan, et al.
Chinese Sci Bull
analysis technique for crustal shear-wave splitting. The
method is mainly based on polarization analysis [20], with
the addition of correlation analysis and a time delay deduction technique [33]. Many studies [22–24,34–38] attest to
the dependable results of SAM.
Shear-wave splitting in the crust employs direct shearwaves observed in near-field recordings, and the seismic
rays used need to be within the shear-wave window. That is
to say, the incidence angle of the shear-wave must be less
than the critical angle of full reflection [39]. In this study,
the depths of the seismic foci used for crustal shear-wave
splitting calculations are at 5–30 km. Near-field recording
data utilize the records from CASN (Capital Area Seismograph Network). According to the station distribution and
recording capabilities of CASN, this research has collected
and sorted CASN seismic data from 2002 to 2005, then
specifically selected waveform records to make calculations
of shear-wave splitting in terms of earthquake parameters in
the earthquake catalog in Capital area of China.
2 Characteristics of crust-mantle seismic anisotropy in North China
Using rigorously selected records from the five NSNC stations
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and the BJT IRIS station in North China to calculate the
SKS splitting parameters, we obtained 81 calculated SKS
splitting results from high-quality waveform recordings
(Table 1). Figure 1 shows the average polarizations of fast
shear-waves from SKS splitting at these five stations.
Results of crustal shear-wave splitting were obtained at
only 60 stations, although there were 107 CASN stations
available. Because fast shear-wave polarization is obviously
influenced by faults beneath or around the stations
[22,40,41], and by irregular topography [42], this study excluded results that were visibly disturbed by surficial tectonics. For the purpose of ensuring the reliability of results,
stations with five or fewer effective records were not adopted.
This leaves results from 21 stations that are available
Table 1 Average polarization azimuths of fast SKS phases in NSNC
stations or IRIS station in North China
Seismic
Networks
stations
BJT
DL2
HNS
TIA
TIY
IRIS
NSNC
NSNC
NSNC
NSNC
Polarization azimuths of
fast SKS phases (°)
104.5
101.7
94.7
135.3
114.8
Standard
errors (°)
Records
22.2
11.3
18.1
10.2
2.6
46
4
20
5
6
Figure 1 Fast axes of seismic anisotropy in North China. The yellow lines are average polarizations of fast crustal shear-waves, the red lines are average
polarizations of fast SKS phases in this study, the blue lines are average polarizations of fast SKS phases in [29,30].
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for discussion in this study (Figure 1). Furthermore, we obtain average polarizations of fast shear-waves by station
averaging in three different data sets (Table 2). In North
China, Chang et al. [29,30] measured SKS splitting from
CASN stations and also from stations of the temporary
North China Seismic Array, deployed by the Institute of
Geophysics, China Earthquake Administration. Figure 1
displays the results of fast shear wave polarizations of SKS
splitting at the 62 stations in this area; average results are
listed in Table 2.
In Figure 1, the fast shear-wave polarizations of SKS
splitting from two dependent research groups are seen to be
very consistent. Fast shear-wave polarizations of direct
crustal shear-waves in northernmost North China are also,
in principle, identical to fast SKS polarizations. According
to Table 2, the average fast shear-wave polarization of SKS
through the upper mantle is obtained at NE 110.17° in this
study. This differs from the NE 108.92° reported elsewhere
[29,30] by only 1.25°. However, the average fast shearwave polarization of crustal direct shear-wave is NE 95.15°,
15.02° different with that of the fast SKS polarization obtained in this study. This suggests that direction of principal
compressive strain in the crust (also direction of principal
compressive stress, in fact) is 15° different than the direction of principal compressive strain in the lithosphere. Figure 2 reveals more intuitive similarities and differences between fast SKS polarizations and fast crustal shear-wave
polarizations.
In North China, SKS results at BJT have been obtained
by several researchers. One reported fast polarization of NE
59°±5° at BJT [43] contrasts with others. However, the fast
polarization calculated by the different Vinnik method [12]
is in harmony with several others [13,14,29] that use the
same SC method. Furthermore, the results in this paper calculated from 46 high-quality data for records spanning 10
years, make it believable that the fast SKS polarization is at
NE 104.5°±22.1°.
The possible reason for the difference in the fast SKS
polarizations is the lower number of records used [43]: only
six teleseismic records from 2000 to 2002 [43,14]. Subsequent research using records by a new eastwardly-marching
temporary array, analyzed SKS anisotropy and deduced its
source to be the result of Proterozoic collision between the
Ordos block and the North China orogenic belt. The SKS
November (2010) Vol.55 No.31
anisotropy observed in a zone running from east of the
North China orogen to the east of the North China Craton
was possibly caused by lithospheric rejuvenation from the
Mesozoic to the Cenozoic. However, SKS data at BJT were
not updated in this work [44]. Note that the BJT is not only
located on the boundary between a basin and an uplifted
block (see Figure 1) [23,24], but it is also on the boundary
between two approximately-orthogonal tensional lithospheric zones [44]. Complex deep structures and different
ray azimuths could also change the seismic waveforms recorded. Differing independent research results from several
stations to the north and west of BJT [13,14,43,44] suggest
that more detailed discussion of the phenomenon is needed.
To evaluate the distribution of anisotropy at depth in
North China, this study obtained azimuthal anisotropy of
the Rayleigh phase velocity at periods between 25 and 85 s
in the same area by inversion. The inverse method applied
was based on frequency dispersion of the phase velocity of
the Rayleigh surface waves, using the station-pair correlation technique [45,46] (Figure 3). Azimuthal anisotropic
Rayleigh phase velocities at different periods (Figure 3)
indicate different fast-velocity directions. According to the
characteristics of resolution kernel functions [45,47], surface waves at different periods are sensitive to different
Earth depth ranges. By and large, the 25–35 s periods are
related to depths of about 25–50 km, and 50–80 s periods
are related to the depths of about 50–160 km. Surface wave
anisotropy reveals that azimuthal anisotropic Rayleigh
phase velocities clearly vary with scales and depths.
3 Discussion of seismic anisotropy in North
China and crust-mantle coupling
There are two main crust-mantle deformation models, SimTable 2 Statistical results of average fast polarization azimuths in North
China, both SKS phases and shear-waves in the crust
Data in North China
Polarization of fast crustal shear-waves
in this study
Polarization of fast SKS phases
in this study
Polarization of fast SKS phases
extracted from Chang et al. [29,30]
Average
(°)
Standard
errors (°)
Stations
95.12
15.35
21
110.17
15.77
5
108.92
10.22
62
Figure 2 Equal-area projection rose diagrams of fast shear-wave polarizations. (a) The yellow rose diagram is the fast SKS polarization used in this study.
(b) The green rose diagram is the fast SKS polarization in North China extracted from [29] and [30]. (c) One is overlapped by the former two diagrams, the
yellow and green colors are the same as in (a) and (b), respectively. The red color shows the full overlapped part of the previous two. (d) The blue rose diagram is the polarization of fast shear-waves from shear-wave splitting in the crust.
GAO Yuan, et al.
Chinese Sci Bull
November (2010) Vol.55 No.31
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Figure 3 Azimuthal anisotropic Rayleigh phase velocity maps of 25, 35, 50, and 85 s in North China. The black short bars represent the magnitude (in
percent) and the fast propagation directions of azimuthal anisotropy.
ple Asthenospheric Flow (SAF) [48] and Vertical Coherent
Deformation (VCD) [49], both of which are based on the
hypothesis of driving-plate force. On the basis of SKS splitting information and surface GPS measurements, Wang et
al. [16] inferred that crust-mantle deformation within the
Tibetan Plateau agrees with the strong coupling VCD crustmantle model. However, in the Yunnan region, outside the
Tibetan Plateau, it is the decoupling SAF crust-mantle
model that applies. The models each have different drive
mechanisms. However, in North China, especially the North
China Basin, because of the thick sedimentary layer at the
Earth’s surface, it is obviously inappropriate to directly
compare GPS measurements and observations in the upper
mantle. Therefore, it is necessary to increase observations
on characteristics in the crust.
Shear-wave splitting obtained from near-field records
mainly uses direct seismic shear waves in the crust, and as a
result is indicative of anisotropic characteristics of the crust.
Although the average azimuth of maximum principal stress
from focal mechanism data and deep well drilling data is at
NW 71.6°, the regional principal compressive stress in
North China generally trends to be have an E-W orientation
[50], and the maximum principal compressive strain is at
NE 85° from GPS measurements showing a good coincidence with the maximum principal compressive stress from
seismic data [51]. The average polarization direction of the
fast shear-wave from shear-wave splitting of near-field data
is at NE 85.7°±41.0° in the Capital area, which suggests a
principal compressive stress field at ENE close to E-W in
accordance with GPS measurements of maximum principal
compressive strain at NE 85° [23].
To reduce the disturbance of faults and irregular tectonic
settings and to abandon stations with either few data samples or samples of lower reliability, we selected 21 of 64
stations. The polarization direction was then calculated for
the direct fast shear-wave in the crust to be NE 95.1°±15.4°.
This corresponds to the background direction of horizontal
crustal principle compressive stress in North China (or at
least in the north of North China). The average fast
shear-wave polarization of SKS splitting through both the
crust and the upper mantle is at NE 110.2°±15.8°. Recent
studies suggest that SKS splitting in the east of China exists
not only in the lithosphere, but also in the upper mantle at
the base of lithosphere. The fast shear-wave polarizations
are in agreement with movement of the Pacific plate moving westwards relative to the Eurasian plate; mantle flow is
inferred to be the main cause of the polarization [14].
To more accurately analyze similarities and differences
between fast shear-wave polarizations of near-field data in
the crust and fast SKS polarizations in the crust and the upper mantle, we have directly compared those stations at
which both polarizations are simultaneously obtained (Table
3). Two sets of results from each of the six stations are obviously different in Table 3. The average directions of fast
shear-wave polarizations at each station have at least 13° of
discrepancy.
Azimuthally anisotropic Rayleigh-waves phase velocities
of different periods indicate different dominant fast velocity
directions. These reveal that, with an increase in depth, the
dominant direction of fast waves gradually shifts from
NW-SE to NNW-SSE. This pattern suggests that crustmantle coupling in North China cannot be explained by the
simple decoupling SAF model or the strong coupling SAF
model. Because of the inhomogeneous crust-mantle structure
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Chinese Sci Bull
November (2010) Vol.55 No.31
Table 3 Comparisons of fast polarization azimuths at several of the same stations, between SKS phases through the mantle and shear-waves in the crust
Station codes
BBS
CHL
DOH
LBP
LQS
MDY
Polarizations of fast SKS phases through the mantle (°)
102.0
134.8
105.7
106.1
114.9
100.7
in North China [3–7], the crust-mantle coupling relationship
in this area possibly follows an inhomogeneous distribution
of the two models or a model that gradually changes in
terms of its physical properties. Considering the ~15° difference in the average polarization of fast shear-waves between the upper crust and the lithosphere, the substantive
deformation in the upper crust and regions below the upper
crust occurred at different points in geological history also
support the likely requirement of model combination. This
certainly needs further confirmation and testing. Because
the crust-mantle coupling model in North China has an important role in studies of geodynamics and deep tectonics,
both locally in East Asia and even globally, this research
still needs more detailed in-depth work.
We thank Professors Kelly Liu and Stephan Gao at the Missouri University
of Science and Technology in the United States for their assistance with the
IRIS data, SKS calculations and discussions of this study. This work was
supported by the National Natural Science Foundation of China
(40674021) and partly by IES project of Institute of Earthquake Science,
China Earthquake Administration (2007-13). We thank two anonymous
reviewers and the editor for their comments and suggestions to improve
this manuscript.
1
2
3
4
5
6
7
8
9
10
Ding G Y. Lithospheric Dynamics of China (in Chinese). Beijing:
Seismological Press, 1991. 1–600
Xu X W, Wu W M, Zhang X K, et al. New Crustal Structure Motion
and Earthquake in Capital Area (in Chinese). Beijing: Science Press,
2002. 1–376
Teng J W, Zeng R S, Yan Y F, et al. Depth distribution of Moho and
tectonic framework in eastern Asia continent and its adjacent ocean
areas. Sci China Ser D-Earth Sci, 2003, 46: 428–446
Liu L, Liu J S, Hao T Y, et al. Seismic tomography of the crust and
upper mantle in the Bohai Bay Basin and its adjacent regions. Sci
China Ser D-Earth Sci, 2007, 50: 1810–1822
Zhang C K, Zhang X K, Zhao J R, et al. Study and review on
crust-mantle velocity structure in Bohai bay and its adjacent areas (in
Chinese). Acta Seismol Sin, 2002, 24: 428–435
Ai Y, Zheng T Y. The upper mantle discontinuity structure beneath
eastern China. Geophys Res Lett, 2003, 30: 2089, doi: 10.1029/2003GL017678
Ai Y, Zheng T Y, Xu W W, et al. Small scale hot upwelling near the
North Yellow Sea of eastern China. Geophys Res Lett, 2008, 35:
L20305, doi: 10.1029/2008GL035269
Gao S, Zhang J F, Xu W L, et al. Delamination and destruction of the
North China Craton. Chinese Sci Bull, 2009, 54: 3367–3378
Zhu R X, Zheng T Y. Destruction geodynamics of the North China
Craton and its Paleoproterozoic plate tectonics. Chinese Sci Bull,
2009, 54: 3354–3366
Menzies M A, Xu Y G, Zhang H F, et al. Integration of geology,
geophysics and geochemistry: A key to understanding the North
China Craton. Lithos, 2007, 96: 1–21
Records
20
6
6
14
12
16
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
Polarizations of fast shear-waves in the crust (°)
129.17
93.33
90.12
92.75
84.50
87.47
Records
6
6
121
8
20
17
Zheng Y F, Wu F Y. Growth and reworking of cratonic lithosphere.
Chinese Sci Bull, 2009, 54: 3347–3353
Zheng S H, Gao Y. Azimuthal anisotropy in lithosphere on the Chinese mainland from observations of SKS at CDSN. Acta Seismol Sin,
1994, 7: 177–186
Luo Y, Huang Z X, Peng Y J. SKS wave splitting study of China and
adjacent regions (in Chinese). Chin J Geophys, 2004, 47: 812–821
Liu K H, Gao S S, Gao Y, et al. Shear-wave splitting and mantle flow
associated with the deflected Pacific slab beneath northeast Asia. J
Geophys Res, 2008, 133: B01305, doi: 10.1029/2007JB005178
Wang C Y, Flesch L M, Silver P G, et al. Evidence for mechanically
coupled lithosphere in central Asia and resulting implications. Geology, 2008, 36: 363–366
Wang C Y, Chang L J, Lü Z Y, et al. Seismic anisotropy of upper
mantle in eastern Tibetan Plateau and related crust-mantle coupling
pattern. Sci China Ser D-Earth Sci, 2007, 50: 1150–1160
Vinnik L P, Farra V, Romanowicz B. Azimuthal anisotropy in the
Earth from observations of SKS at GEOSCOPE and NARS broadband stations. Bull Seism Soc Am, 1989, 79: 1542–1558
Silver P G, Chan W W. Shear wave splitting and subcontinental mantle deformation. J Geophys Res, 1991, 96: 16429–16454
Iidaka T, Niu F. Mantle and crust anisotropy in the eastern China region inferred from waveform splitting of SKS and PpSms. Earth
Planets Space, 2002, 53: 159–168
Crampin S. Seismic wave propagation through a cracked solid: Polarization as a possible dilatancy diagnostic. Geophys J R Astron Soc,
1978, 53: 467–496
Crampin S, Peacock S, Gao Y. et al. The scatter of time-delays in
shear-wave splitting above small earthquakes. Geophys J Int, 2004,
156: 39–44
Gao Y, Zheng S H, Sun Y. Crustal crack anisotropy in Tangshan.
Acta Seismol Sin, 1995, 8: 351–363
Gao Y, Wu J. Compressive stress field in the crust deduced from
shear-wave anisotropy: An example in capital area of China. Chinese
Sci Bull, 2008, 53: 2840–2848
Wu J, Gao Y, Chen Y T, et al. Seismic anisotropy in the crust in
northwestern capital area of China. Chin J Geophys, 2007, 50: 210–
221
Wu J, Gao Y, Chen Y T. Shear-wave splitting in the crust beneath the
southeast Capital area of North China. J Seism, 2009, 13: 277–286
Zhang Z J, Li Y K, Lu D Y, et al. Velocity and anisotropy structure
of the crust in the Dabieshan orogenic belt from wide-angle seismic
data. Phys Earth Planet Inter, 2000, 122: 115–131
Zhang Z, Teng J, Badal J, et al. Construction of regional and local
seismic anisotropic structures from wide-angle seismic data: Crustal
deformation in the southeast of China. J Seism, 2009, 13: 241–252
Gao Y, Teng J W. Studies on seismic anisotropy in the crust and
mantle on Chinese Mainland (in Chinese). Prog Geophys, 2005, 20:
180–185
Chang L J, Wang C Y, Ding Z F. A study on SKS splitting beneath
Capital area of China (in Chinese). Acta Seismol Sin, 2008, 30:
551–559
Chang L J, Wang C Y, Ding Z F. Seismic anisotropy of upper mantle
in eastern China. Sci China Ser D-Earth Sci, 2009, 52: 774–783
Liu K H. NA-SWS-1.1: A uniform database of teleseismic shearwave splitting measurements for North America. G-Cubed, 2009, 10:
Q05011, doi: 10.1029/2009GC002440
GAO Yuan, et al.
32
33
34
35
36
37
38
39
40
41
Chinese Sci Bull
Gao S S, Liu K H. Significant seismic anisotropy beneath the southern Lhasa Terrane, Tibetan Plateau. G-Cubed, 2009, 10: Q02008, doi:
10.1029/2008GC002227
Gao Y, Shi Y T, Liang W, et al. Systematic analysis method of
shear-wave splitting SAM(2007): Software system (in Chinese).
Earthq Res China, 2008, 24: 345–353
Tai L X, Gao Y, Shi Y T, et al. A study of shear-wave splitting in the
crust by Liaoning Telemetry Seismic Network of China (in Chinese).
Seism Geol, 2009, 31: 401–414
Shi Y T, Gao Y, Zhao C P, et al. A study of seismic anisotropy of
Wenchuan earthquake sequence (in Chinese). Chin J Geophys, 2009,
52: 398–407
Zheng X F, Chen C H, Zhang C H, et al. Study on temporal variations of shear-wave splitting in the Chiayi area, aftershock zone of
1999 Chichi earthquake, Taiwan (in Chinese). Chin J Geophys, 2008,
51: 149–157
Gao Y, Wang P D, Zheng S H, et al. Temporal changes in
shear-wave splitting at an isolated swarm of small earthquakes in
1992 near Dongfang, Hainan Island, southern China. Geophys J Inter,
1998, 135: 102–112
Gao Y, Crampin S. Temporal variations of shear-wave splitting in
field and laboratory in China. J Appl Geophys, 2003, 54: 279–287
Crampin S, Peacock S. A review of shear-wave splitting in the compliant crack-critical anisotropic Earth. Wave Motion, 2005, 41: 59–77
Tadokoro K, Ando M. Evidence for rapid fault healing derived from
temporal changes in S wave splitting. Geophys Res Lett, 2002, 29:
1047, doi: 10.1029/2001GL013644
Cochran E S, Li Y G, Vidale J E. Anisotropy in the shallow crust observed around the San Andreas fault before and after the 2004 M6.0
November (2010) Vol.55 No.31
42
43
44
45
46
47
48
49
50
51
3605
Parkfield earthquake. Bull Seism Soc Am, 2006, 96: S364–S375, doi:
10.1785/0120050804
Gao Y, Crampin S. A further stress-forecast earthquake (with hindsight), where migration of source earthquakes causes anomalies in
shear-wave polarizations. Tectonophysics, 2006, 426: 253–262
Zhao L, Zheng T Y. Using shear wave splitting measurements to investigate the upper mantle anisotropy beneath the North Craton.
Geophys Res Lett, 2005, 32: L10309, doi: 10.1029/2005GL022585
Zhao L, Zheng T Y, Lü G. Insight into craton evolution: Constraints
from shear wave splitting in the North China Craton. Phys Earth
Planet Inter, 2008, 168: 153–162
Yi G X, Yao H J, Zhu J S, et al. Rayleigh-wave phase velocity distribution in China continent and its adjacent regions (in Chinese).
Chin J Geophys, 2008, 51: 402–411
Yi G X, Yao H J, Zhu J S, et al. Lithospheric deformation of continental China from Rayleigh wave azimuthal anisotropy (in Chinese).
Chin J Geophys, 2010, 53: 256–268
Xu G M, Yao H J, Zhu L B, et al. Shear wave velocity structure of
the crust and upper mantle in western China and its adjacent area (in
Chin). Chin J Geophys, 2007, 50: 193–208
Richardson R M. Ridge forces, absolute plate motions, and the intraplate stress field. J Geophys Res, 1992, 97: 11739–11748
Lithgow-Nertelloni C, Ricards M A. The dynamics of Cenozoic and
Mesozoic plate motions. Rev Geophys, 1998, 36: 27–78
Xu Z H. A present-day tectonic stress map for Eastern Asia region (in
Chinese). Acta Seismol Sin, 2001, 23: 492–501
Zhang G M, Ma H S, Wang H, et al. The relation between active
blocks and strong earthquakes in China (in Chinese). Sci China Ser
D-Earth Sci, 2004, 34: 591–599