Vol.5, No.8A1, 46-55 (2013) Natural Science
http://dx.doi.org/10.4236/ns.2013.58A1006
Stress rise precursor to earthquakes in the Tibetan
Plateau
Zhenhan Wu1*, Qunce Chen2, Patrick J. Barosh3, Hua Peng2, Daogong Hu2
1Chinese Academy of Geological Sciences, Beijing, China; *Corresponding Author: wuzhenhan@sohu.com
2Institute of Geomechanics, Chinese Academy of Geological Sciences, Beijing, China
3P.J. Barosh and Associates, Bristol, USA
Received 11 May 2013; revised 11 June 2013; accepted 18 June 2013
Copyright © 2013 Zhenhan Wu et al. This is an open access article distributed under the Creative Commons Attribution License,
which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
ABSTRACT
Earthquake prediction thus far has proven to be
a very difficult task, but changes in situ stress
appear to offer a viable approach for forecasting
large earthquakes in Tibet and perhaps other
continent al regions. High stress anom alies formed
along active faults before large earthquakes and
disappeared soon after the earthquakes oc-
curred in the Tibetan Plateau. Principle stress
increased up to ~2 - 5 times higher than back-
ground stress to form high stress anomalies
along causative faults before the Ms 8.1 West
Kunlun Pass earthquake in November 2001, Ms
8.0 Wenchuan earthquake in May 2008, Ms 6.6
Nimu earthquake in October 2009, Ms 7.1 Yushu
earthquake in April 2010 and the Ms 7.0 Lushan
earthquake in April 2013. Stress near the epi-
centers rapidly increased 0.1 0 - 0.12 MPa ov er 45
days, ~8 months before the Ms 6.6 Nimu earth-
quake occurred. The high principle stress ano-
malies decreased quickly to the normal stress
state in ~8 - 12 months after the Ms 8.1 West
Kunlun Pass and the Ms 8.0 Wenchuan earth-
quakes. These high stress anomalies and their
demise appear directly related to the immediate
stress rise along a fault prior to the earthquakes
and the release during the event. Thus, the
stress rise appears to be a viable precursor in
prediction of large continental earthquakes as in
the Tibetan Plateau.
Keywords: Earthquake Prediction; High Stress
Anomalies; In-Situ Stress Measurement; Large
Earthquakes; Seismic Faul t; Tibetan Plateau
1. INTRODUCTION
Large continental earthquakes are a major geologic
hazard and commonly result in great disasters as recently
occurred in China. The 2008 Ms 8.0 Wenchuan earth-
quake destroyed towns and villages along and near the
seismic faults, and killed 69,227 people with 17,923 still
missing [1]. The 2010 Ms 7.1 Yushu earthquake killed
2192 people with an add itional 78 missing, and the 2008
Ms 6.6 Nimu earthquake resulted in significant economic
loss. The Ms 7.0 Lushan earthquake occurred on April 20,
2013 killed 196 people with 21 still missing in south-
western Longmenshan Mts. Another event, the 2001 Ms
8.1 West Kunlun Pass earthquake, might have caused
further devastation, but for it stroke a sparsely populated
region. The Chinese government has encouraged scien-
tists to develop effective ways for tracing and predicting
large earthquakes, aiming at decreasing seismic hazards.
However, earthquake prediction has thus far proven a
difficult task for the world’s scientists even though seis-
mic monitoring systems are established in many coun-
tries. Here we use stress to investigate these four large
earthquakes in the Tibetan Plateau in hopes of finding a
viable precursor for future earthquake prediction.
Ever since Reid [2] formulated the elastic rebound
theory following the 1903 San Francisco earthquake,
researchers have considered the relation of stress change
and earthquakes. Li and his colleagues advocated the
prediction of earthquakes by in-situ stress measurement
in the 1960s [3,4] and considerable work has been ac-
complished ever since on measuring stress and delineat-
ing stress regions in China [5-7]. The lithosphere stress
state now has been widely probed by in-situ stress meas-
urements [8,9], but care must be used in relating these to
earthquakes, because the measured stress may reflect the
stress unrelated to the present tectonic movement [6,10].
Furthermore, although the delineation of general levels
of stress can relate to general levels of seismic activity
[11] this does not relate to activity along specific fault
zones. Neither did estimates of deep stress arrive from
epicentral distribution and focal plane solutions [12].
Copyright © 2013 SciRes. OPEN A CCESS
Z. H. Wu et al. / Natural Science 5 (2013) 46-55 47
Direct measured changes in the stress fields, however,
reflect the present day movement in the crust [4,11] and
where these changes are adjacent to active faults they
may relate to the seismic activity along the fault. Even
small changes in stress, such as due to reservoir filling,
are enough to trigger earthquakes sometimes [3]. Inves-
tigations into the crustal stress present and possible
changes have been underway for the past decade for both
engineering purposes and earthquake studies in the Ti-
betan Plateau now have revealed several changes in
measured stress.
Intensive seismicity in the Tibetan Plateau is caused
by the continued northward subduction of Indian Conti-
nental Plate that has created a variety of seismically ac-
tive faults [13-15], which have produced large earth-
quakes over the past ten years in western China (Figure
1). The Ms 8.1 West Kunlun Pass earthquake occurred on
November 14, 2001 and formed a fracture zone 350 -
426 km long on the Kusai Lake fault with a co-seismic
sinistral slip of 7.6 - 8.0 m near Kusai Lake [16] and 3.5
- 4.7 m near Kunlun Pass [17]. The Ms 8.0 Wenchuan
earthquake of May 12, 2008 formed a seismic rupture
zone with a length of 240 - 270 km along the Beichuan-
Yingxiu fault [18,19] and triggered thousands of large-
scale landslides, huge rock falls and debris flows in the
Longmenshan Moun tain s [1], at th e eastern margin of the
Tibetan Plateau. Co-seismic offsets of 4.6 m dip-slip and
6.1 m dextral-slip were measured in Yingxiu and
Beichuan, respectively [1,20]. The Ms 7.1 Yushu earth-
quake, which occurred on April 14, 2010, formed a seis-
mic fracture zone with a length up to 23 km along the
Garze-Yushu fault and co-seismic sinistral slips of 1.2 -
1.8 m happened near the epicenter northwest of Yushu.
And the Ms 7.0 Lushan earthquake, which occurred on
April 20, 2013, formed seismic hazards, landslides and
rock falls without seismic rupture zone along the eastern
marginal thrust in southwestern Longmenshan Moun-
tains. These large earthquakes, together with the Ms 7.9
Mani earthquake that occurred on November 8, 1997,
constitute the most recent activity on the faults bounding
the Hohxil-Bayanhar-Garze structural block of the
northern Tibetan Plateau (Figure 1). Earthquakes that
Figure 1. Tectonic map of active faults and seismicity in the Tibetan Plateau. Explanation: 1, Main Boundary Thrust (MBT); 2,
Holocene thrust fault; 3, Holocene strike-slip fault; 4, Holocene normal fault; 5, Pleistocene thrust and strike-slip faults; 6, Ms 8.0 -
8.5 earthquake; 7, Ms 7.0 - 7.9 earthquake; 8, Ms 6.0 - 6.9 earthquake; 9, Ms 5.0 - 5.9 earthquake; 10, epicenter of earthquake in
recent years; 11, location, magnitude and date of earthquake; 12, hydraufracturing stress measurement; 13, piezomagnetic stress
measurement. The GLR refers to the Golmud-Lhasa Railway. The MN, WK, DC, YS, NM, WC and LS refer to the Mani, West of
Kunlun Pass, Dong Co, Yushu, Nimu, Wenchuan and Lushan earthquakes, respectively. The XTG, XG-1, XG-2, WL, SYG, KMG,
KDG, YJG, YXG, MX, BXG and others marked by yellow refer to the sites for stress measurement.
Copyright © 2013 SciRes. OPEN A CCESS
Z. H. Wu et al. / Natural Science 5 (2013) 46-55
48
occurred in the central Tibetan Plateau, such as the Ms
5.6 Dongco earthquake on March 7, 2004 and the Ms 6.6
Nimu earthquake on October 6, 2008, resulted from ac-
tivity along the boundary normal faults of the Yadong-
Yangbajain-Gulu graben system.
2. STRESS CHANGES BEFORE AND
AFTER LARGE EARTHQUAKES
Stress measurements by both the hydraulic fracturing
and piezomagnetic methods have been taken in boreholes
about the Tibetan Plateau since 2001 to provide data to
characterize the stress field in which the large earth-
quakes occur and for engineering work. The great major-
ity of the sites are in granite and gabbro. Hydraulic frac-
turing stress measurements were made in Xidatan granite
(XTG), Wudaoliang limestone (WL), And o g a bb r o (AG ),
Northeastern Yangbajain granite (NYG), Northwestern
Quxi granite (NQG), Eastern Quxi granite (EQG) [21]
along Golmud-Lhasa Railway across the Tibetan Plateau
(Table 1). Hydraulic fracturing stress measurements in
the Yaoji granite (YJG) [22], Yingxiu granite, Kangding
granite (KDG ) [19], Maoxian (MX) an d Guanyuan (GY)
[23] were conducted before and after the Ms 8.0 Wen-
chuan earthquake in central Longmenshan Mountains at
the eastern margin of the Tibetan Plateau (Figure 1).
Piezomagnetic stress measurements were undertaken
in t he X idatan granite (XG-1) and Xidatan gab bro (XG -2 )
[24], Hohxil granite (HG), Fenghuoshan siltstone (FS),
Yanshiping sandstone (YSP), South Ando granite (SAG)
[7], Southeastern Yangbajain granite (SYG), Lhasa gran-
ite (LG) and Kangma granite (KG) [25] (Figure 1).
These contributed valuable data (Table 2) for construc-
tion of the Golmud-Lhasa railway and revealed an obvi-
ous stress change before and after the Ms 8.1 West
Kunlun Pass earthquake [24]. And Piezomagnetic stress
measurement in the Baoxing Granite (BXG) and Hy-
draulic fracturing stress measurement in the Luding (LD)
were conducted before the Ms 7.0 Lushan earthquake in
the southwestern Longmenshan Mountains.
Stress is measured at different depths in order to for-
mulate the stress increase due to the additional ro ck mass
with depth. Stress was measured by hydraulic fracturing
on December 6, 2005 in a 301 m deep borehole in the
Northeastern Yangbajain granite (NYG), east of Yangba-
jain graben. The maximum principle stress (SH) and
minimal principle stress (Sh) at NYG increase from 4.62
MPa and 3.82 MPa, respectively, at a depth 60 m to
11.34 MPa, and 10.20 MPa at 286 m (MPa = 145.0377
psi) (Ta b le 1). The stress change with depth is found to
be SH = 2.56 + 0.0340 D and Sh = 1.34 + 0.0325 D with
D referring to depth in meters. The NYG is located in
central Lhasa block, ~9 km away from the active fault
along the western boundary of the Yangbajain graben,
and seismicity surrounding NYG is very weak (Figure 1).
The stress recorded in NYG is therefore taken as repre-
sentative for relatively stable areas in the Tibetan Plateau
and is used as the background stress in analyzing stress
anomalies (Figures 2 and 3).
Several other sites, AG, WL, LG and GY, also are lo-
cated in relative stable areas away from seismic faults
and seismic zones (Figure 1), and are characterized by
relatively lower principle stress similar to NYG (Figures
2 and 3). Measurements along the Golmud-Lhasa rail-
way found S H and Sh in AG changed from 4.50 MPa and
3.82 MPa, respectively, at a depth of 50 m to 5.56 MPa
and 5.00 MPa, respectively, at 135 m; the SH and Sh in
WL changed from 3.33 MPa and 2.30 MPa, respectively,
at a depth of 28 m to 7.78 MPa and 5.10 MPa at 116 m;
and the SH and Sh in LG was 4.6 MPa and 2.6 MPa, re-
spectively, at a depth of 18 m (Figures 2 and 3). At the
northwest margin of the South China Block, SH increased
from 6 MPa at 100 m depth to 20 MPa at 347 m and Sh
increased from 5 MPa at a depth of 100 m to 10 MPa at
347 m in Guanyuan (GY), northeast of Chengdu (Fig-
ures 2 and 3).
In contrast, the maximum principle stress SH found
along the active faults is abnormally high; always 2 - 5
times higher than in NYG; and the minimal principle
stress Sh along the fault zones also increased before large
earthquakes in the northern, eastern and central Tibetan
Plateau. These formed high stress zones in SH-D (Figure
2) and Sh-D diagrams (Figure 3).
2.1. West Kunlun Pass Earthquake (WK)
The principle stress SH and Sh increased to 12.9 MPa
and 12.1 MPa, respectively, at XG-1 at a depth of 18 m
and 6.8 MPa and 4.4 MPa at XG-2 at a depth of 14 m in
August 2001 (Table 2), ~3 months before the Ms 8.1
West Kunlun Pass earthquake [24]. The SH and Sh then
decreased to 3.5 MPa and 3.2 MPa, respectively at XG-1
at a depth of 18 m and 2.2 MPa and 1.2 MPa, respec-
tively, in XG-2 at 14 m depth in July 2002 (Table 2), ~8
months after the Ms 8.1 West Kunlun Pass earthquake
[24]. The principle stress SH and Sh at XTG decreased to
2.32 - 7.88 MPa and 2.20 - 5.70 MPa, respectively, be-
tween depths of 44 and 152 m and 11.07 - 10.74 MPa
and 7.0 - 6.5 MPa, at depths of 168 - 176 m (Figures 2
and 3).
2.2. Wenchuan Earthquake (WC)
The Ms 8.0 Wenchuan earthquake on May 12, 2008
resulted from an eastward thrust of the Songpan-Garze
terrain over the South China Block [18,20]. The maxi-
mum principle stress (SH) in the eastward thrust sheet
was measured at 14.44-25.53 MPa from depths of 180.3
m to 280.5 m at YJG in 1999, ~9 years before the earth-
quake. This was in contrast with general values of 7.8
Copyright © 2013 SciRes. OPEN A CCESS
Z. H. Wu et al. / Natural Science 5 (2013) 46-55 49
Table 1. Stress measured by hydraulic fracturing in the Tibetan Plateau.
Hydraulic fracturing parameters (MPa) Stress (MPa)
Site and rock/date
measured Depth
(m) Pb Pr Ps Po T SH S
h S
v
Orientation
of SH
44.0 5.92 4.25 2.20 0.03 1.67 2.32 2.20 1.15 N21˚E
64.0 7.66 4.03 2.30 0.23 3.63 2.64 2.30 1.67
84.0 8.92 6.40 3.50 0.44 2.52 3.66 3.50 2.20 N29˚E
126.0 7.40 7.03 5.20 0.86 0.37 7.71 5.20 3.29
152.0 10.29 8.10 5.70 1.12 2.18 7.88 5.70 3.98 N43˚E
168.0 9.36 8.66 7.00 1.27 0.70 11.07 7.00 4.38 N34˚E
Xidatan granite
(XTG)/August, 2005
176.0 8.70 7.40 6.50 1.36 1.30 10.74 6.50 4.59 N42˚E
50.0 7.97 6.24 3.82 0.50 1.73 4.72 3.82 1.50
65.0 8.03 6.30 3.82 0.66 1.73 4.50 3.82 1.98 N10˚W
93.0 8.67 7.01 4.82 0.93 1.66 6.52 4.82 2.79
129.0 9.45 8.10 5.14 1.29 1.35 6.03 5.14 3.88 N9˚W
Wudaoliang limestone
(WL)/August, 2006
135.0 10.01 8.08 5.00 1.36 1.93 5.56 5.00 4.07
28.0 4.74 3.40 2.30 0.16 1.33 3.33 2.30 0.79 N11˚W
55.0 6.13 3.22 2.20 0.43 2.90 2.94 2.20 1.55
75.0 7.13 5.12 3.60 0.63 2.01 5.05 3.60 2.11 N24˚W
91.0 5.92 5.62 4.00 0.79 0.30 5.58 4.00 2.56
Ando gabbro
(AG)/October, 2005
116.0 8.23 6.48 5.10 1.04 1.75 7.78 5.10 3.26 N13˚W
60.0 7.97 6.24 3.82 0.60 1.73 4.62 3.82 1.81
85.0 8.13 6.30 3.82 0.86 1.83 4.30 3.82 2.57 N55˚E
113.0 8.87 7.31 4.82 1.14 1.56 6.02 4.82 3.41
139.0 10.25 9.10 6.14 1.40 1.15 7.92 6.14 4.19
165.0 11.31 10.08 6.16 1.66 1.23 6.75 6.16 4.97 N46˚E
209.0 14.20 12.41 8.39 2.09 1.79 10.67 8.39 6.27
222.0 14.40 12.30 8.10 2.23 2.10 9.77 8.10 6.68
243.0 16.60 14.10 9.20 2.44 2.50 11.06 9.20 7.31
261.0 18.30 16.90 10.8 2.62 1.40 12.88 10.80 7.85 N65˚E
Northeastern Yangbajain granite
(NYG)/December, 2005
286.0 18.73 16.40 10.2 2.86 2.33 11.34 10.20 8.59 N53˚E
73.8 16.84 13.34 8.54 0.54 3.50 11.73 8.54 1.96
115.8 23.58 11.76 9.03 0.96 11.82 14.36 9.03 3.07
N46.5W
122.3 16.18 10.72 8.63 1.03 5.46 14.15 8.63 3.24 N39.6W
Northwestern Quxi granite
(NQG)/July, 2007
134.8 18.52 9.72 7.65 1.15 8.80 12.07 7.65 3.57
133.0 25.43 6.84 5.75 0.90 18.60 9.51 5.75 3.60
170.0 - 6.12 6.80 1.27 - 13.01 6.80 4.60
241.0 24.10 12.60 10.90 1.98 11.50 18.12 10.90 6.50 N3.0˚E
283.0 16.43 11.00 10.31 2.40 5.43 17.53 10.31 7.60
Eastern Quxi gr a nite
(EQG)/After Cao et al., 2003
[21]
296.0 24.80 11.12 9.08 2.53 13.60 13.59 9.08 8.00
180.3 9.04 8.34 8.28 1.08 0.7 15.42 8.28 4.77
187.6 12.72 8.95 8.19 1.15 3.77 14.44 8.19 4.96 N57˚E
224.4 14.23 12.46 11.61 1.51 1.77 20.86 11.61 5.49 N63˚E
233.3 16.69 13.66 11.11 1.60 3.03 18.07 11.11 6.18 N1˚W
250.3 12.29 10.89 10.80 1.77 1.40 19.74 10.80 6.63 N55˚E
259.1 13.69 11.81 11.68 1.85 1.88 21.38 11.68 6.86
Yaoji granite (YJG)/after
Mao et al., 1999 [22]
280.5 15.60 13.00 13.5 3
2.06 2.60 25.53 13.53 7.42
Copyright © 2013 SciRes. OPEN A CCESS
Z. H. Wu et al. / Natural Science 5 (2013) 46-55
50
Continued
90.0 4.30 3.50 2.60 0.82 0.80 3.48 2.60 2.39
128.0 13.62 12.78 7.44 1.20 0.84 8.34 7.44 3.39
142.0 9.95 8.70 5.95 1.34 1.25 7.81 5.95 3.76 N56˚W
171.0 18.21 18.18 11.81 1.63 0.03 15.62 11.81 4.53
Yingxiu granite (YXG)/after
Wu et al., 2009 [19]
185.0 12.73 10.17 8.35 1.77 2.56 13.11 8.35 4.90
55.0 4.47 3.27 1.70 0.31 1.20 1.74 1.70 1.46 N5˚E
81.0 4.66 3.91 2.44 0.57 0.75 2.84 2.44 2.15 N81˚E
94.0 4.10 3.61 2.52 0.70 0.49 3.25 2.52 2.49
117.0 5.03 3.93 2.31 0.93 1.10 2.46 2.42 3.10
136.0 9.81 6.12 3.55 1.12 3.69 3.67 3.55 3.60
172.0 17.32 11.47 5.92 1.48 5.85 6.41 6.12 4.56
Kangding granite (KDG)/after
Wu et al., 2009 [19]
186.0 10.91 6.89 4.94 1.62 4.02 6.31 4.94 4.93
Luding (LD) 150.0 16.00 10.00 4.00 N60˚W
Maoxian (MX) 229.0 14.00 8.00 6.00 N55˚W
100.0 6.00 5.00 2.65 N30˚W
200.0 7.50 7.00 5.30 N35˚W
Guanyuan (GY)/after
An et al., 2004 [23] 347.0 20.00 10.00 9.20
Explanation: Pb, break down pressure; Pr, re-opening pressure; Ps, shut-in pressure; Po: pore pressure; T, tensor strength; SH, horizontal maximum principle
stress; Sh, horizontal minimal principle stress; Sv, vertical stress caused by overloading rocks with density 2.63 (g/cm3), 2.70 (g/cm3) or 3.02 (g/cm3). Stress
of LD, MX and GY came from An et al., 2004 [23]. Sites of measured stress are marked by yellow in Figure 1.
MPa at depths of 170 m found to the northwest [6]. The
stress then had decreased to 3.48 - 8.34 MPa between
depths of 90 m to 142 m at YXG and 1.74 - 6.41 MPa
from depths of 55 m to 186 m at KDG in 2009 (Figure
2), one year after the Wenchuan earthquake. The minimal
principle stress (Sh) also changed from high anomaly at
YJG before the Wenchuan earthquake to normal in YXG
at depths of 90 - 142 m and in KDG at depths of 55 - 186
m after the earthquake (Figure 3). The principle stress
still remained at higher values at greater depths. The SH
and Sh was 13.11 - 15.62 MPa and 11.81 - 8.35 MPa,
respectively, at depths of 171 - 185 m in Yingxiu (YXG)
along the seismic Beichuan-Yingxiu fault one year after
the Wenchuan earthquake (Ta bles 1 and 2). High princi-
ple stress also occurred in Maoxian (MX) along the
seismic Beichuan-Yingxiu fault, and the SH and Sh were
14 MPa and 8 MPa, respectively, in MX at a depth of
229 m (Tab l e 1 ). However, the stress had remained low
with SH, 6 - 7.5 MPa, and Sh, 5.0 - 7.0 MPa in GY at
depths of 100-200 m in the stable South China Block
[23], ~4 years before the Wenchuan earthquake.
2.3. Dongco Earthquake (DC)
The Ms 5.6 Dongco earthquake, which was due to
normal fault offset in the Yadong-Yangbajain-Gulu gra-
ben system, was preceded by a high stress anomaly in the
South Ando granite (SAG) (Figures 2 and 3). Principle
stress SH and Sh reached 8.1 MPa and 4.8 MPa, respec-
tively, in SAG at a depth of 14 m in July 2003; this is
more than 2 times higher than background stress (Fig-
ures 2 and 3), and ~8 months later the Dongco earth-
quake occurred southwest of SAG in the Ando-Dongco
graben on March 7, 2004 (Figure 1).
2.4. Nimu Earthquake (NM)
A high stress anomaly also was found adjacent to the
Yadong-Yangbajain graben system before the Ms 6.6
Nimu earthquake occurred on October 6, 2008. Prin ciple
stress SH and Sh was as h igh as 5.7 - 10.4 MPa and 4 .6 -
8.4 MPa, respectively, in SYG at a depth of 12 - 13 m in
October-November 2001, and reached 11.73-14.36 MPa
and 7.65 - 9.03 MPa at a depth of 73.8 - 134.8m in NQG
in July 2007 (Figures 2 and 3), one year before the Nimu
earthquake. Stress in NQG at a depth of 31 - 35 m in-
creased quickly ~8 months before the earthquake; S1,
oriented N 40 ˚W, changed from 7.855 MPa to 7.958 MPa;
S2, oriented S80˚W changed from 9.627 MPa to 9.751
MPa; and S3, oriented N20˚E, changed from 7.312 MPa
to 7.426 MPa. Thus S1, S2 and S3 increased 0.103 MPa,
0.124 MPa and 0.114 MPa, respectively, in 45 days from
January 13 to February 26, 2008 (Figure 4). However,
the principle stress in relatively stable areas away from
Yadong-Yangbajain graben system remained lower (Fig-
ure 2) even though the measurement sites are not located
too far from the epicenter of the Nimu earthquake. The
SH and Sh in NYG ranged from 4.62 MPa and 3.82 MPa,
respectively, at 60 m depth to 11.34 MPa and 10.20 MPa
at a depth of 286 m in December 2005, and SH and Sh in
Copyright © 2013 SciRes. OPEN A CCESS
Z. H. Wu et al. / Natural Science 5 (2013) 46-55 51
Figure 2. Vertical change of maximum principle stress in the
Tibetan Plateau. Explanation: SH, maximum principle stress of
Yangbajain granite at NYG; Sh, minimal principle stress of
Yangbajain granite at NYG; Sv1 and Sv2, vertical stress caused
by overlying rocks with average densities of 3.02 g/cm3 and 2.7
g/cm3 respectively. The shaded area refers to high stress zone
for large earthquakes.
EQG ranged between 9.51 - 18.12 MPa and 5.75 - 10.90
MPa, respectively, at dep ths of 133 - 283 m in 2003 ( Ta-
ble 1).
2.5. Yushu Earthquake (YS)
The Ms 7.1 Yushu earthquake followed high stress in
the Hohxil gr anite (HG) and Fenghuoshan siltston e (FS).
Principle stress SH and Sh were 6.8 MPa and 3.2 MPa,
respectively, in HG at a depth of 20 m in May 2002; 4.6 -
5.5 MPa and 2.8 - 2.9 MPa, respectively, in FS at depths
of 12 - 16 m in August 2002; being 1.8 - 2.7 times higher
than background stress (Figure 5). The high stress in HG
and FS formed along the Wudaoliang and Fenghuoshan
sinistral-slip faults, which are en echelon or b ranch faults
of Garze-Yushu fault which broke during the earthquake.
The Yushu earthquake occurred on April 14, 2010 along
southern boundary faults of Hohxil-Bayanhar-Garze block
(Figure 1).
2.6. Lushan Earthquake (LS)
The Ms 7.0 Lushan earthquake occurred along the
Eastern Marginal Thrust, southwestern Longmenshan
Mts. on April 20, 2013, ~5 years after the Ms 8.0 Wen-
chuan earthquake along the Beichuan-Yingxiu fault, cen-
tral Longmenshan Mts. High stress anomalies were
found in the Lud ing (LD) (Figures 2 and 3) and Baoxing
Figure 3. Vertical change of minimal principle stress in the
Tibetan Plateau. Explanation: same as Figure 2.
Figure 4. Diagram of stress changes in Northwestern Quxi
granite. Explanation: S1, S2 and S3 represents piezomagnetic
stress measured in bore hole at depth of 31 - 35 m at orienta-
tions of N40˚W, S 80˚W and N20˚, respectively, from January
13 to February 26, 2008.
granite (BXG) (Figure 5) before the Ms 7.0 Lushan
earthquake. The SH and Sh were 16 MPa and 10 MPa,
respectively, in LD at 150 m depth (An et al., 2004), and
the principle stress SH and Sh increased to 9.8 MPa and
7.9 MPa, respectively, in Baoxing Granite (BXG) at
depth of 18 - 22 m in September 2009, ~3.5 years before
the Ms 7.0 Lushan earthquake (Table 2).
3. CONCLUSIONS AND DISCUSSION
The principle stress along the seismically active faults
generally rose to ~2 - 5 times higher than background
stress before large earthquakes occurred in the Tibetan
Plateau and high stress anomalies near seismic faults
were precursors of large earthquakes (Figures 2, 3 and
Copyright © 2013 SciRes. OPEN A CCESS
Z. H. Wu et al. / Natural Science 5 (2013) 46-55
Copyright © 2013 SciRes.
52
Table 2. Stress measured by piezomagnetic method in Tibetan Plateau.
Site and rock Date Depth (m) SH (Mpa) Sh (Mpa) SH orientation Reference
Xidatan granite (XG-1) August 2001 18 12.9 12.1 N45˚E [24]
Xidatan granite (XG-1) July 2002 18 3.5 3.2 N66˚E [24]
Xidatan gabbro (XG-2) August 2001 14 6.8 4.4 N58˚E [24]
Xidatan gabbro (XG-2) July 2002 14 2.2 1.2 N5˚W [24]
Hohxil granite (HG) May 2002 20 6.8 3.2 N26˚E [7]
August 2002 16 5.5 2.9 N84˚E [7]
Fenghuoshan siltstone (FS) August 2002 12 4.6 2.8 N61˚E [7]
Yangshiping sandstone (YSP) June 2003 13 5.6 4.4 N47˚E [7]
South Ando granite (SAG) July 2003 14 8.1 4.8 N64˚W [7]
October 2001 13 10.4 8.4 N70˚E [25]
October 2001 12 5.7 2.7 N81˚E [25]
Southeastern Yangbajain granite (SYG)
November 2001 12 6.6 4.6 N45˚E [25]
Lhasa granite (LG) October 2003 18 4.0 2.6 N38˚W [25]
Kangma granite (KMG) September 2003 13 5.2 4.4 N49˚W [25]
Baoxing granite (BXG) September 2009 18 - 22 9.8 7.9 N51˚W [19]
Yingxiu Granite (YXG) September 2009 20 4.3 2.7 N19˚E [19]
Kangding Granite (KDG) Septe mber 2009 20 2.6 1.8 N39˚E [19]
Figure 5. Diagram of piezomagnetic principle stress change in the Tibetan Pla-
teau. Explanation: the SYG, KMG, FS and BXG et al. refer to the sites fo r pie-
zomagnetic stress measurement, and the YS 7.1/2010/4/14 et al. refer to the re-
lated earthquakes occurred in recent years.
5). Maximum principle stress (SH) and minimal principle
stress (Sh) along the seismic fault increased to 6.8 - 12.9
MPa and 4.4 - 12.1 MPa, respectively, at a depth of 14 -
18 m, being 2.5 - 5.2 times higher than background stress
~3 months before the Ms 8.1 West Kunlun Pass earth-
quake in the northern plateau, and decreased to normal
OPEN A CCESS
Z. H. Wu et al. / Natural Science 5 (2013) 46-55 53
stress state ~8 months after the earthquake (Table 2). The
SH and Sh in Yaoji granite on eastward thrust sheet in-
creased to 14.44 - 25.53 MPa at depths of 180.3 - 280.5
m before the Ms 8.0 Wenchuan earthquake, being ~2
times higher than background stress, and recovered to a
normal stress state one year after the earthquake in
Longmenshan Mountains at the eastern margin of the
Tibetan Plateau (Figures 2 and 3). The SH and Sh in-
creased to 9.8 MPa and 7.9 MPa, respectively, in BXG at
depth of 18 - 22 m, and 16 MPa and 10 MPa, respec-
tively, in LD at 150 m depth before the Ms 7.0 Lushan
earthquake. The principle stress SH and Sh increased to
2.2 - 4.2 times higher than background stress before the
Ms 6.6 Nimu earthquake; stress in 3 orientations rapidly
increased 0.10 - 0.12 MPa within 45 days near seismic
epicenter ~8 months before the Nimu earthquake in the
southern Tibetan Plateau (Figure 4). A high stress anom-
aly also formed in Fenghuoshan (FS) and Hohxil (HG)
along seismic faults before the Ms 7.1 Yushu earthquake
occurred in April 2010.
Additional high stresses were also found in the Yan-
shiping sandstone (YSP) where the SH and Sh were 5.6
MPa and 4.4 MPa, respectively, at a depth of 13 m in
June 2003, and in th e Kangma Gr anite (KMG) where th e
SH and Sh were 5.2 MPa and 4.4 MPa, respectively, at a
depth 13m (Table 2). If the maximum stress SH continues
to increase as much as 0.5 - 1.0 MPa in the related areas,
then the YSP and KMG will be plotted in the high stress
anomaly in SH-Sh diagram (Figure 5). This high stress
anomaly could be connected with some Ms 6.0 - 7.0
earthquake in the near future.
Significantly different types of fault zones show the
stress increase even though they might be compressional
or extensional structures. The West Kunlun Pass and Yu-
shu earthquakes were due to strike-slip offset, the Wen-
chuan earthquake was due to oblique-slip thrust offset,
the Lushan earthquake was due to thrust offset and the
Nimu and Dongco earthquakes were due to normal fault
offset. Thus, the fault type makes no obvious difference
in the development of stress anomalies prior to an earth-
quake. Stress variations relative to rock mechanic
changes [26] and tectonic divisions [6], local stress from
non-tectonic processes as permafrost freezing [27] and
ancient residual stress [10] might cause local stress
anomalies, but these factors rarely lead to regional stress
anomalies along active faults and result in regular stress
changes before and after large earthquakes.
Apparently deep barriers acting as friction decrease
slip rates or even stop slip along active faults and in-
crease stress along the blocked segments of active faults,
leading to high stress anomalies before large earthquakes
(Figures 2, 3 and 5). This is a reflection of the strain
build up near faults as proposed by Reid [2], but the re-
sulting stress seems more restricted and the buildup is
more rapid than what might be expected. These charac-
teristics aid in using high stress anomalies in the upper
crust surface as viable precursors for prediction of large
earthquakes within continents, such as the Tibetan Pla-
teau.
Other indices as Coulomb failure stress on faults
[28,29], tectonic stress and stress variations inferred from
numerical modeling [12,30-32], and hydrochemistry
anomalies [33] also have been suggested in forecasting
earthquakes, but none are as sensitive to earthquakes as
the in-situ measured stress in the Tibetan Plateau. The
GPS measurements indicated low slip rates of active
faults and low velocity of terrains in the Longmenshan
Mountains [15], where the Wenchuan earthquake oc-
curred, and no high velocity or strain anomalies were
discovered by GPS measurements before the Ms 8.0
Wenchuan earthquake, the Ms 8.1 West Kunlun Pass
earthquake, the Ms 6.6 Nimu earthquake, the Ms 7.1
Yushu earthquake and the Ms 7.0 Lushan earthquake in
the Tibetan Plateau, implying that GPS measurements
are not nearly as effective as in-situ stress measurements
for earthquake prediction. Using stress to monitor earth-
quakes appears a practical approach for forecasting large
continental earth quakes.
4. ACKNOWLEDGEMENTS
This research was supported by the Ministry of Land and Resources
of China under grant No. 201211095 and China Geological Survey
under grant Nos. 1212011120185 and 1212011221111. Thanks to the
Tibetan Bureau of Geology and Mineral Resources for their help in
field drilling, and thanks to the expert who reviewed the manuscript.
REFERENCES
[1] Wu, Z.H., Barosh, Patrick, J., Zhang, Z.C. and Liao, H.J.
(2012) Effects from the Wenchuan Earthquake and seis-
mic hazard in the Longmenshan Mountains at the eastern
margin of the Tibetan Plateau. Engineering Geology, 143-
144, 28-36. doi:10.1016/j.enggeo.2012.06. 006
[2] Reid, H.F. (1910) Mechanics of the earthquake, the Cali-
fornia Earthquake of April 18, 1906. Report of the State
Investigation Commission, Carnegie Institution of Wash-
ington, Washing ton DC.
[3] Li, S.-G. (1974) Earthquake geology. Science Press, Bei-
jing.
[4] Li, F.Q. (2010) In-situ stress measurement is an important
approach to realize earthquake prediction—Developing
J.S. Lee’s scientific ideas on earthquake prediction. In:
Xue and Furen, Eds., Rock Stress and Earthquakes, CRC
Press, Taylor and Francis Group, London, 757-759.
[5] Chen, Q.X. (1998) Analysis of rock mechanics and tec-
tonic stress field. Geology Publishing House, Beijing.
[6] Yao, R., Yang, S.X., Lu, Y.Z., Cui, X.F., Chen, Q. and Mi,
Q. (2010) Characteristics of tectonic stress in the east of
Tibetan Plateau and its neighboring region inferred from
Copyright © 2013 SciRes. OPEN A CCESS
Z. H. Wu et al. / Natural Science 5 (2013) 46-55
54
in-situ stress measurements. In: Xue and Furen, Eds.,
Rock Stress and Earthquakes, CRC Press, Taylor and
Francis Group, London, 687-693.
[7] Wu, M.L., Zhang, C.S., Liao, C.T., Ma, Y.S. and Ou, M.Y.
(2005) The recent state of stress in the central Qing-
hai-Tibet Plateau according to in-situ stress measure-
ments. Chinese Journal of Geophysics, 48, 327-332.
[8] Zoback, M.L. (1992) First and second order patterns of
stress in the lithosphere: The world stress map project.
Journal of Geophysical Research, 97, 11703-11728.
doi:10.1029/92JB00132
[9] Heidbach, O., Tingay, M., Barth, A., Reinecker, J., Kurfe,
D. and Miller, B. (2008) The release 2008 of the world
stress map. www.world-stress-map.org
[10] Barosh, P.J. (1986) Neotectonic movement, earthquakes
and stress state in the eastern United States. Tectonophys-
ics, 132, 117-152. doi:10.1016/0040-1951(86)90029-6
[11] Xie, F.R., Zhang, H.Y. and Du, Y. (2010) The recent tec-
tonic stress districts and strong earthquakes in China. In:
Xue and Furen, Eds., Rock Stress and Earthquakes, CRC
Press, Taylor and Francis Group, London, 35-40.
[12] Zhang, Y.-Q. and Xie, F.-R. (2010) Background stress
state estimated from 2008 Wench uan earthquake sequence.
In: Xue and Furen, Eds., Rock Stress and Earthquakes,
CRC Press, Taylor and Francis Group, London, 707-712.
[13] Molnar, P. and Tapponnier, P. (1978) Active tectonics of
Tibet. Journal of Geophysical Research, 83, 5361-5375.
doi:10.1029/JB083iB11p05361
[14] Tapponnier, P., Peltzer, A. Y., Le, Dain, Amijo, R. and
Cobbold, P. (1982) Propagating extrusion tectonics in
Asia: New insights from simple experiments with plas-
ticine. Geology, 10, 611-616.
doi:10.1130/0091-7613(1982)10<611:PETIAN>2.0.CO;2
[15] Zhang, P.Z., Shen, Z.K., Wang, M., Gan, W.J., Burgmann,
R., Molnar, P., Wang Q., Niu, Z.J., Sun, J.Z., Wu, J.C.,
Sun, H.R. and You, X.Z. (2004) Continuous deformation
of the Tibetan Plateau from global positioning system
data. Geology, 32, 809-812. doi:10.1130/G20554.1
[16] China Seismological Bureau (2003) Album of the Ms 8.1
earthquake occurred in west of Kunlun Pass, China. Seis-
mological Press, Beijing, 1-105.
[17] Wu, Z.H., Wu, Z.H., Hu, D.G., Wang, W., Zhang Z.C. and
Lei, W.Z. (2005) Album of active faults and geological
hazards along the Golmud-Lhasa Railway across the Ti-
betan Plateau. Seismological Press, Beijing, 1-150.
[18] Xu, X.W., Yu, G.H., Chen, G.H., Ran, Y.K., Li, C.X.,
Chen, Y.G. and Chang, C.P. (2009) Parameters of coseis-
mic reverse- and oblique-slip surface ruptures of the 2008
Wenchuan earthquake, eastern Tibetan Plateau. Acta Ge-
ologica Sinica, 83, 673-684.
doi:10.1111/j.1755-6724.2009.00091.x
[19] Wu, M.L., Zhang, Y.Q., Liao, C.T., Chen, Q., Ma, Y.S.,
Wu, J.S., Yan, J.F. and Ou, M.Y. (2009) Preliminary re-
sults of in-situ stress measurements along the Longmen-
shan fault zone after the Wenchuan Ms 8.0 earthquake.
Acta Geologica Sinica, 83, 746-753.
doi:10.1111/j.1755-6724.2009.00098.x
[20] Wu, Z.H., Dong, S.W., Barosh, P.J., Zhang Z.C. and Liao,
H.J. (2009) Dextral-slip thrust faulting and seismic events
of the Ms 8.0 Wenchuan earthquake Longmenshan Moun-
tains, eastern margin of the Tibetan Plateau. Acta Geo-
logica Sinica, 83, 685-693.
doi:10.1111/j.1755-6724.2009.00092.x
[21] Cao, Z.Q., Xie, P., Jin, H., Chen, Q. and Mao, J.Z. (2003)
Variety characteristics of the crustal stress field near the
Brahmaputra fault zone. Progress in Geophysics, 18, 167-
172.
[22] Mao, J.Z., Li, F.Q., Zhang, Z.G., Chen, Q., Ceng, J.Q. and
Yang, X. (1999) Report on stress measurement by hy-
draulic fracturing in Yaoji reservoir dam. Institute of
Crust Dynamics, China Seismological Bureau, Beijing.
[23] An, Q.M., Ding, L.F., Wang, H.Z. and Zhao, S.G. (2004)
Research of property and activity of Longmenshan Moun-
tain fault zone. Journal of Geodesy and Geodynamics, 24,
115-119.
[24] Liao, C.T., Zha ng, C.S., Wu, M.L., Ma, Y.S. and Ou, M.Y.
(2003) Stress change near the Kunlun Fault before and
after the Ms 8.1 Kunlun Earthquake. Geophysical Re-
search Letter, 30, 2027-2030.
doi:10.1029/2003GL018106
[25] Zhang, C.S., Wu, M.L., Liao, C.T., Ma, Y.S. and Ou, M.Y.
(2007) The result of current stress measurements and
stress state analysis in the region of Yangbajain-Kangmar
in T ibet. Chinese Journal of Geophysics, 50, 517-522.
[26] Hudson, J.A. and Feng, X.T. (2010) Variability of in situ
rock stress. In: Xue and Furen, Eds., Rock Stress and
Earthquakes, CRC Press, Taylor land Francis Group,
London, 3-10.
[27] Wu, Z.H., Barosh, P.J., Wang, L.J., Hu, D.G. and Wang,
W. (2008) Numerical modeling of stress and strain asso-
ciated with bending of an oil pipeline by a migrating
pingo in the permafrost region of the northern Tibetan
Plateau. Engineering Geology, 96, 62-77.
doi:10.1016/j.enggeo.2007.10.001
[28] Shan, B., Xiong, X., Zheng, Y. and Diao, F.Q. (2009)
Stress changes on major faults caused by Mw 7.9 Wen-
chuan earthquake, May 12, 2008. Science in China Series
D: Earth Sciences, 52, 593-601.
doi:10.1007/s11430-009-0060-9
[29] Hori, T. and Kaneda, Y. (2004) Physical criterion to
evaluate seismic activity associated with the seismic cy-
cle of great intraplate earthquakes. Journal of Seismology,
8, 225-233. doi:10.1023/B:JOSE.0000021364.93301.2a
[30] Spudich, P., Guatteri, M., Otsuki, K. and Minagawa, J.
(1998) Use of fault striations and dislocation models to
infer tectonic stress during the 1995 Hyogo-Ken Nanbu
(Kobe) earthquake. Bulletin of Seismological Society of
America, 88, 413-427.
[31] Kato, N. and Hirasawa, T. (1999) The variation of
stresses due to aseismic sliding and its effect on seismic
activity. Pure and Applied Geophysics, 155, 425-442.
doi:10.1007/s000240050273
[32] Tiampo, K.F., Bowman, D.D., Colella, H. and Rundle,
J.B. (2008) The stress accumulation method and pattern
informatics index: Complementary approaches to earth-
quake forecasting. Pure and Applied Geophysics, 165,
Copyright © 2013 SciRes. OPEN A CCESS
Z. H. Wu et al. / Natural Science 5 (2013) 46-55
Copyright © 2013 SciRes. OPEN A CCESS
55
693-709. doi:10.1007/s00024-008-0329-5
[33] Harmann, J. and Levy, K.J. (2006) The influence of
seismotectonics on precursory changes in underground-
water composition for the 1995 Kobe earthquake, Japan.
Hydrogeology Journal, 4, 1307-1318.
doi:10.1007/s10040-006-0030-7