Estimation of recurrence interval of large earthquakes on the central Longmen Shan fault zone based on seismic moment accumulation/release model

Hindawi Publishing CorporationThe Scientific World JournalVolume 2013 Article ID 458341 8 pageshttpdxdoiorg1011552013458341

Research ArticleEstimation of Recurrence Interval of Large Earthquakeson the Central Longmen Shan Fault Zone Based on SeismicMoment AccumulationRelease Model

Junjie Ren and Shimin Zhang

Key Laboratory of Crustal Dynamics Institute of Crustal Dynamics China Earthquake Administration Beijing 100085 China

Correspondence should be addressed to Junjie Ren renjunjiegmailcom

Received 29 April 2013 Accepted 11 June 2013

Academic Editors B V Kozelov and G Spada

Copyright copy 2013 J Ren and S ZhangThis is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Recurrence interval of large earthquake on an active fault zone is an important parameter in assessing seismic hazard The 2008Wenchuan earthquake (Mw 79) occurred on the central Longmen Shan fault zone and ruptured the Yingxiu-Beichuan fault(YBF) and the Guanxian-Jiangyou fault (GJF) However there is a considerable discrepancy among recurrence intervals of largeearthquake in preseismic and postseismic estimates based on slip rate and paleoseismologic results Post-seismic trenches showedthat the central Longmen Shan fault zone probably undertakes an event similar to the 2008 quake suggesting a characteristicearthquake model In this paper we use the published seismogenic model of the 2008 earthquake based on Global PositioningSystem (GPS) and Interferometric Synthetic Aperture Radar (InSAR) data and construct a characteristic seismic momentaccumulationrelease model to estimate recurrence interval of large earthquakes on the central Longmen Shan fault zone Ourresults show that the seismogenic zone accommodates a moment rate of (27plusmn 03)times 1017Nmyr and a recurrence interval of3900plusmn 400 yrs is necessary for accumulation of strain energy equivalent to the 2008 earthquake This study provides a preferredinterval estimation of large earthquakes for seismic hazard analysis in the Longmen Shan region

1 Introduction

Recurrence interval of large earthquakes closely associ-ated with dynamic process of the seismogenic fault is akey parameter for seismic hazard assessment on a seismicfault especially on large-scale fault zones [1 2] The 2008Wenchuan earthquake (Mw 79) broke the central LongmenShan fault zone and caused the loss of large property andmany thousands of lives [3 4] It ruptured the YBF and GJF[4] The most concern for local residents is how often largeearthquakes occur on the Longmen Shan fault zone

Several methods are used to estimate recurrence intervalof large earthquakes on the central Longmen Shan faultzone Based on the ratio of coseismic displacement andlong-term GPSgeologic slip rate the average recurrenceintervals for large earthquakes were roughly estimated to2000ndash10000 yrs [5] 3000ndash6000 yrs [3] and sim4000 yrs [6]However this method includesmany uncertainties due to thehomogeneity of coseismic slip along the fault trace [4 7 8]

Paleoseismologic excavation is direct and effective to obtainthe interval of large earthquakes [2] Due to limitations anduncertainties of dating techniques however the results of dif-ferent authors reveal a remarkable discrepancy of recurrenceinterval even in the same trench Preseismic trenches at Leiguand Baishuihe towns along the YBF showed that the penulti-mate event occurred at 1381ndash1177 ka based on radiocarbondating [9 10] In the same Qingshiping trench Li et al andDensmore et al suggested the interval of 3830 and 930 yrsrespectively based on radiocarbon dating along the GJF [10ndash12] Many trenches have been excavated across the coseismicsurface rupture following the 2008 earthquake (Figure 1)Some trencheswere emplaced at Yingxiu Xiaoyudong Leiguand Pingtong towns along the BYF and others at Bailu townalong the GJF (Figure 1) Lin et al proposed a recurrenceinterval of sim1000ndash1200 yrs in the Yingxiu and Leigu trenchesbased on archaeological evidence and radiocarbon dating[13] The trenches at Yingxiu Xiaoyudong Leigu and Bailutowns using radiocarbon dating showed a recurrence interval

2 The Scientific World Journal

998771

998771

998771

998771

998771

998771

998771

998771

998771

998771

998771

998771

Sa

Sb

Sc

Sd

Se

Sf

Sg

Hangwang

Pingwu

PingtongGuixi

Nanba

Pengzhou

Shifang

Mianzhu

Heishui

Chengdu

Mianyuan R

Minjiang R

Minjiang R

Fujiang R

T

LG Jiangyou

Anxian

Mianyang

BC

QC

QCF

YX

MX

Lixian

DJY

WCWMF

0 2010

SC

Sichuan

Basin

Orodos

Indian Plate

Tarim Basin

MSF

HYF

QP

XYDBL

GJFYBF

Tibetan Plateau

0

Main shock

Trench location

Place name

Surface rupture

Active faultRiverFocal sectionBorder of fault model

Focal mechanismBlind fault

998771

aftershock

T

6070

II

I

III

Alti

tude

(m)

ATF

KFHF

XF

JLF

RF

Saga

ing

Himalayas

20

10

0

Foca

l dep

th (k

m)

YBF GJF

40(km)

minus150

940

A

A-A998400

A998400

105∘E104

∘E103∘E

33∘N

32∘N

31∘N

Mlt5Mge5

A A998400

(km)

Figure 1 Tectonic settings and aftershock sequence of the 2008 Wenchuan earthquake Surface rupture is modified from [4] focalmechanisms are from USGS aftershock sequence is from relocated results [28] Borders of fault model are according to GPS and InSARinversion [6] Trench sites are from published results [12ndash14] White circles are place names BC Beichuan county BL Bailu town DJYDujiangyan city LG Leigu town MX Maoxian county QC Qingchuan county QP Qingping town WC Wenchuan county XYDXiaoyudong town YX Yingxiu town Black solid lines are known faults YBF Yingxiu-Beichuan fault GJF Guanxian-Jiangyou fault WMFWenchuan-Maoxian fault QCF Qingchuan fault MSF Minshan fault HYF Huya fault Insert map shows the topography of the Tibetanplateau Inset map shows major tectonics in the Longmen Shan vicinity ATF Altyn Tagh fault HF Haiyuan fault JLF Jiali fault KF Kunlunfault RF Red River fault XF Xiaoshuihe fault I Qaidam-Qilian block II Bayan Har block III Sichuan-Yunan block Black arrows indicateblock motion direction

of 2300ndash3300 yrs [14 15]The trenches of Li et al at PingtongGuixi and Nanba towns from optically stimulated lumines-cence (OSL) and radiocarbon dating revealed a sim11000 yrinterval [12] Liu et al advised a recurrence interval of 1100ndash2100 yrs in the Leigu trench utilizing OSL and radiocarbondating [16] However Wen et al recommended that therecurrence interval of large earthquakes in and adjacent tothe 2008 epicenter area is longer than 2000 yrs according tohistorical earthquake activity [17]

Significant discrepancies between these results confusethe public that which value is preferred for large earthquakeon the Longmen Shan fault zone In this paper we construct a

characteristic seismic moment accumulationrelease modelbased on fault geometry of the seismogenic zone and estimatethe average recurrence interval of earthquakes similar to the2008 shock along the central Longmen Shan fault zone

2 Characteristic Seismic MomentAccumulationRelease Model

Seismic activity is a process of energy accumulation andrelease [18] Seismic moment is a measure of the size of anearthquake in terms of the energy released and is associated

The Scientific World Journal 3

with the seismogenic zone on a fault [19] The characteristicseismic moment accumulationrelease model agrees withthe energy balance principle and assumes that the momentreleased by an earthquake is equal to the accumulation alonga seismic fault during an recurrence interval

If the mean moment of repeated earthquakes M0(in

Nm) and the long-term moment accumulation rate on theseismic fault119872

0(in Nmyr) are known their ratio would

define the average recurrence interval of earthquakes T (inyr) [20]

119879 =1198720

1198720

(1)

Formodern earthquakes seismicmoment (1198720) is usually

estimated from seismograms Seismic moment can also beconverted from the moment magnitude (119872

119908) using the

formula of Hanks and Kanamori [21]The long-term moment accumulation rate on each fault

segment is represented as a rectangular fault patch withuniform secular slip rate The moment rate of each segment(1198720119904) is obtained from seismogenic area (119860) in km2 and long-

term slip rate (]) in mmyr

1198720119904= 120583119860] (2)

where 120583 is the shear modulusThe seismogenic area (119860) is the area of fault plane

ruptured in an earthquake (Figure 2)

119860 = 119871119882119877 (3)

where 119871 is segment length the distance between two segmen-tation points119882 is down-dip segment width correspondingto the thickness of the brittle upper crust in which strainenergy available to be released as earthquakes is stored If thefault plane is oblique W is the ratio of the epicenter depth(119867) and the sine of dip angle (120579) 119882 = 119867sin(120579) If thefault plane is vertical 119882 is equal to the focal depth (119867) 119877is a slip scaling factor (ranging from 0 to 1) that accounts forthe role of fault creep in reducing the fault slip available forearthquake rupture and varies from 119877 = 0 (all slip occursaseismically) to 119877 = 1 (all slip occurs in earthquakes)

Then the moment rate along each fault segment (1198720119904)

can be defined by the formula

1198720119904=120583119871119867119877]

sin (120579) (4)

So the moment rate of the total seismogenic zone is thesum of all the segments

1198720= sum119872

0119904 (5)

Assume that similar-size large earthquakes or character-istic earthquakes always occurred along a seismic fault andthe moment accumulation rate is constant then Formula (1)can be used to approximately estimate recurrence interval oflarge earthquake on this fault

W

H

Base of seismogenic

zone

Seismogenic area A of

segment 2

Segment 1 Segment 2

Segment 3Groundsurface

L120579

Figure 2 Conceptual illustration of a segmented oblique fault Alsoshown aremeasures of length 119871 down-dipwidth119882 epicenter depth119867 and dip angle 120579

3 Tectonic Settings of the 2008Wenchuan Earthquake

The 2008Wenchuan earthquake occurred on the central partof the northeast-trending Longmen Shan thrust belt whichbounds the eastern margin of the Tibetan plateau and ischaracterized by the steepest relief along any margin of theTibetan plateau [5]TheLongmen Shan thrust belt issim500 kmlong and consists of three main subparallel thrust faults theWenchuan-Maoxian fault YBF and GJF (Figure 1) whichmerged at the basal detachment sim15ndash20 km deep and formedan imbricated thrust fault system [22] Crustal shortening onthis system is the possible main cause for uplift of easternTibet [23]

The 2008 earthquake ruptured the central LongmenShan fault zone and generated the sim240 km and sim70 kmsurface rupture along the YBF and GJF respectively [4] Thecoseismic surface rupture ismainly expressed by thrust slip inthe south and equivalent strike and thrust slip componentsin the north [4 24] Seismic-wave inversion showed that asim300 km-long rupture in the seismogenic zonewas generatedduring the 2008 earthquake [25]

4 Seismic Moment Released ina Recurrence Cycle

Seismic moment is released in a recurrence cycle includingmain shocks aftershocks and interseismic earthquakes Theseismic moment released by the 2008 main shock and someaftershocks has been calculated from the amplitude spectra ofseismic waves [26] Other earthquakes only has surface-wavemagnitudes Hence the conversion relationship betweenscalar moment and surface-wave magnitude in the LongmenShan area is required for our analysis

Zheng et al estimated scalar seismic moment of themain shock and 33 aftershocks bigger than119872

11990450 based on

waveform data from National Digital Seismograph Networkand regional seismograph network of China [26] All the 34samples are used to establish the regression relationship ofsurface-wave magnitude (119872

119904) versus scalar seismic moment

(in Nm) by least-squares fitting (Figure 3)

Log1198720= 16119872

119904+ 80 (6)

The correlation coefficient is 098


45 5 55 6 65 7 75 8 85

EarthquakesRegression lineConfidence interval (95)

2008 earthquake

Ms

(Nm

)M

0

1e+15

1e+16

1e+17

1e+18

1e+19

1e+20

1e+21

1e+22

LogM0 = 16 Ms + 80

Figure 3 Regression line of seismic moment (1198720) and surface

magnitude (119872119904) Data include the main shock and 33 aftershocks

with119872119904ge 50 during the 2008 earthquake [43]

From 12 May 2008 to 1 December 2012 there are 749119872119904ge 40 aftershocks occurred Before the 2008 earthquake

seismic activity in historical and instrumental records merelyincludes fourmoderately strong earthquakes the 1597119872

11990450

191311987211990450 1958119872

11990462 and 1999119872

11990454 earthquakes [17]

Using formula (6) the scalar moment released by119872119904ge 40

aftershocks and interseismic earthquakes is 205 times 1019NmThe 2008 main shock is equivalent to Mw 79 accordingto USGS and China Earthquake Administration and thereleased scalar moment is 104 times 1021Nm using the con-version formula [21] So the scalar seismic moment releasein a whole recurrence cycle is 106 times 1021Nm showing thataftershocks and moderate earthquakes play a minor role(sim2) in the release of seismic moment along the centralLongmen Shan fault zone

5 Moment Accumulation Rate inthe Seismogenic Zone

51 Fault Geometry Inversion of seismic waves and fieldinvestigation suggested that the seismogenic zone of the2008 earthquake can be divided into several segments whichrepresents a complicated rupture process in this earthquake[4 25 27] Detailed fault geometry of the seismogenic zoneassociated with this earthquake was modeled based on GPSand InSAR data [6] In this fault model the BYF dips to thenorthwest at a moderate dip of sim43∘ at the southwest end ofthe rupture belt reachingsim50∘ at NanbaThe fault has a dip ofsim56∘ across the Nanba step-over and increases progressivelyto near vertical at the northeast terminal of the rupture TheGJF generally dips sim28∘

52 Focal Depth (119867) The seismogenic zone associated withthe 2008 earthquake is complex and each segment has adifferent focal depth According to the fault model [6] sixsegments (SandashSf) are divided along the YBF and a separatepatch (Sg) is along the GJF (Figure 4(a) Table 1)

The 2553 aftershocks from May 12 to July 8 2008 wererelocated according to different velocity models for the eastand west side of the Longmen Shan fault zone [28] usingdouble-difference algorithm [29] To estimate the preferredseismogenic depth of each segment the frequency histogramof aftershock focal depth and the regression curve of Gaus-sian distribution in each segment are made The regressionresults pass the Shapiro-Wilk Normality test Preferred depthof each segment is estimated from the regression mean(Figures 4(b)ndash4(g) Table 1)

Seismic reflection data and well logs indicate that theYBF and GJF merge at the base of the seismogenic zonewhich appears to root into a detachment in the mid-crust[22 23 30 31]The lack of aftershocks and a shallow dip anglealong the Sg segment suggest a common root shared with theSb segment of the BYF at the seismogenic depth a result inagreement with balanced geological cross-sections across thesouthern Longmen Shan thrust zone [23 30] Therefore thefocal depth of the Sb segment is assigned to the Sg segment(Table 1)

53 Slip Rates along the Central Longmen Shan Fault Faultslip rate can be derived from geological field investigationand geodesy Geological rate is an average value of long-term tectonic movement and is constraint by dated offsetmarker units while geodetic fault slip rate estimates arebased on model based inferences from interseismic velocitygradients From a long-term respective both slip rates can beapproximately equivalent [32]

Geological observation andGPS surveys show a relativelylow slip rate along the Longmen Shan thrust zone and somedifferences between geological and GPS rates (Table 1)Giventhe uncertainties in the estimation of geological rates GPSslip rates are preferred in our calculations For segments Sband Sg where there is a lack of GPS result geological rates areused

54 Moment Accumulation Rate To estimate moment accu-mulation rate on all the segments we integrate the thrustand dextral slip rate components along down-dip and strikeUsing formula (4) moment accumulation rate of each seg-ment is calculated in Table 1 assuming a shear modulus of120583 = 30GPa in the crust and a slip scaling factor 119877 of 09given large thrust slip on the Longmen Shan fault belt Thetotal moment accumulation rate of the seismogenic zone is267 times 10

17Nmyr using formula (5)Model uncertainty is prevalent in estimating the recur-

rence interval because the characteristic moment accumu-lationrelease model depends on some assumptions anduncertain input parameters

In ourmodel slip rate on each fault segment is assumed tobe constant with time Although some fault zones have beenfound to change of slip rate during the late Quaternary [33ndash35] slip rate along the Longmen Shan fault belt is roughlycomparable (Table 1)

Other assumption is moment balancing which demandsthat all the moments accumulated in the interseismic periodare released by the earthquakes in a recurrence cycle Thecentral Longmen Shan thrust belts are composed of not


SaSb

ScSd

SeSf

Sg

33 1031035

1041045

1051055

106

02040

325 32 315 31 305

Dep

th(k

m)

QingchuanNanba

Beichuan

YingxiuGJFN

Latitude (∘N)

Long

itude

(∘ E)

96∘

56∘

49∘49∘

44∘

43∘

43∘

28∘50∘

(a)

0 10 20 30

Afte

rsho

ck n

umbe

r

0

20

40

60

80

100Aftershock num 825

Focal depth (km)

Preferred mean 1274km

(b)

Afte

rsho

ck n

umbe

r

010203040506070

Aftershock num 417

0 10 20 30Focal depth (km)


(c)

Afte

rsho

ck n

umbe

r

05

101520253035

Aftershock num 627


Preferred mean 985 km

(d)

Afte

rsho

ck n

umbe

r

05

101520253035

Aftershock num 148


Preferred mean 15km

(e)

Afte

rsho

ck n

umbe

r

0

20

40

60

80

100


Aftershock num 657Preferred mean 1332km

(f)

Afte

rsho

ck n

umbe

r

05

10152025303540

Aftershock num 211



(g)

Figure 4 Fault model and focal depth of the seismogenic zone along the central Longmen Shan fault zone (a) Fault geometry and segmentsviewed from the southwest at 45∘ elevation angle (modified from [6]) Borders of fault segmentation are shown in Figure 1 (b)ndash(g) arestatistic results of focal depth for segments SandashSf respectively according to the relocated aftershocks [28] Statistical samples of each segmentare aftershocks enclosed by segment borders as shown in Figure 1 Black solid lines are regression curves of Gaussian distribution which passthe Shapiro-Wilk Normality test The value of preferred mean is estimated from the regression result

Table 1 Parameters of fault model and accumulation moment rate in the seismogenic subsegments

Seismogenic zone Dextral rate(GPS Geol)(mmyr)

Reverse rate(GPS Geol)(mmyr)

Secular Rate(GPS Geol)(mmyr)

Moment rate(1016 Nmyr)Segment Length (km) Dip (∘) Depth (km)

Sa 68 43 1274 17 10 14 03ndash06 22 12 838Sb 62 44 1477 13 054 141 475Sc 41 49 985 17 096 14 11 22 12 353Sd 51 50 1500 08 03 085 240Se 60 56 1332 08 03 085 231Sf 47 90 1403 08 03 085 158Sg 63 28 1477 089 023 092 119Dip angles and GPS rates are from [6 39] as shown in Figure 3 geological rates are from [9ndash11 46] depth values are from Figure 4 Moment rate is calculatedusing formula (4)


only the three main faults but also some blind thrust faultsin the Sichuan basin as shown in Figure 1 Postseismicinvestigations showed that the 2008 earthquake also formedsmall folds (sim10ndash20 cm) and coseismic cracks on the groundsurface in the Sichuan basin [36] which suggests a small por-tion of moment may be released by these blind thrust faultsin the basin In addition although postseismic deformationmoderate and small earthquakes and the influence of otheradjacent large earthquakes exist on the Longmen Shan faultbelts [37 38] they play aminor role in strain accommodationin a recurrence interval

Slip rate is a crucial input parameter in our modelContinuous GPS survey across the fault zone provides anaccurate slip rate [39] However along some parts of faultzone there is a lack of continuous GPS stations In theestimation of geological rate accurate offset and formationage of geomorphic surface are required [2] An accurateoffset demands a clear geomorphologic marker Owing tonumerous external factors erosion human activity and soon these markers are prone to be destroyed and illegibleAge of geomorphic surface needs a sample that presentsthe formation and an appropriate dating technique Variousdatingmethods have their own limitations For example OSLdemands a bleached sufficiently luminescence signal andradiocarbon needs autochthonous carbonaceous materialand to be well-preserved (ie not obviously contaminatedwith carbon not original to itself ) [40]

The slip scaling factor 119877 is another parameter thatinfluences the moment rate and represents the role of faultcreep in the release of seismic moment Although fault creepis found on numerous faults especially on large-scale strike-slip faults [41] there is lack of detailed study about the 119877-factor on the Longmen Shan fault zone In this calculationthe 119877 value of 09 is adopted because of more difficulties ofcreep slip on thrust faults than on strike-slip and normalfaults Whether this value is suitable for the Longmen Shanfault zone needs further work

The uncertainties in all the parameters involved in thiscalculation are hard to be determined precisely The areaof seismogenic zone and slip rate along the fault segmentsgenerally have a 10 uncertainty in the rupture model [6]respectively Thus we infer that sim20 uncertainty should beconsidered in our model So the total moment accumulationrate of the seismogenic zone is (27plusmn03) times 1017Nmyr in theseismogenic zone

6 Recurrence Behavior and Interval ofLarge Earthquakes

Postseismic trenches at Yingxiu Xiaoyudong Leigu Ping-tong Guixi Nanba and Bailu towns along the 2008 coseis-mic surface rupture (Figure 1) revealed that the penulti-mate large earthquake had a coseismic offset similar to the2008 earthquake [10ndash15] consistent with the result of offsetgeomorphology [27] In other word the central LongmenShan fault zone probably undertakes the repeated earthquakesimilar to Mw 79 consistent with a characteristic earth-quake model [42] Small and moderate earthquakes mightprobably be background earthquakes in a recurrence cycle

Using formula (1) the average recurrence interval of largeearthquakes similar to the 2008 earthquake along the centralLongmen Shan fault belt is 3900 plusmn 400 yrs

In addition China has a long record of earthquake espe-cially for Xirsquoan city ever the capital of several dynasties in theChinese history and is sim400 km away from the 2008 surfacerupture and felt strong motion in the 2008 earthquake Thecity began to have a detailed document since at least 316 BC(the age of the reign of Qin Dynasty) The earliest writtenliterature on earthquakes was a felt earthquake occurring at263AD [43] Since that time the catalog of large earthquakesis probably complete Dujiangyanweir located inDujiangyanCounty west Chengdu City and only several kilometers awayfrom the 2008 surface rupture (Figure 1) is a famous waterconservation project and was constructed in the QinDynasty(sim200 BC) Since that time Chengdu ever the capital of ShuKingdom in ancient China has become the most importanteconomic and political center If a large earthquake similarto Mw sim79 even occurred in the Longmen Shan region thecounty annals of adjacent areas like Chengdu andXirsquoan citieswould give a literature record about this quake Accordingto the documents of historical earthquakes there is a lackof great earthquake in the 2008 epicenter area and adjacentregions [43] To sum up the recurrence interval of largeearthquakes along the central Longmen Shan fault zone isgreater than sim2300 yrs

The recurrence intervals of Densmore et al [11] Lin et al[13] and Liu et al [16] are shorter than the time span ofearthquake record The main reason could be as follows Thearchaeological materials found in the trench might be relatedto postearthquake human activity and not to the penultimateearthquakesThe ages of radiocarbon dating are younger dueto polluted samples by newer carbonaceous matters [2 44]The result of Li et al is apparently older than the time spanof earthquake record [12] The reason could be that the OSLsamples of colluvium related to the earthquake might nothave been bleached sufficiently [45]

Our result is probably not a real value but a preferredestimate of average interval The real recurrence intervalneeds further carefully dating of trench sampling This valuewill provide a relatively reasonable recurrence interval for thecentral Longmen Shan fault zone

As the boundary fault zone between the Tibetan plateauand Sichuan basin the Longmen Shan thrust zone hasaccommodated the strain from eastward extrusion of theTibetan plateau The strain is released by seismic slip alongthrust faults within the Longmen Shan thrust fault zone andexhibited by great relief However geodetic measurementsand geomorphic investigations show that east-west shorten-ing across the range is relatively small (lt3mmyr) [10 39 4647] in comparisonwith that of other border faults around theTibetan plateau This limited rate might need a millennial-scale interval to accumulate the strain energy equivalent tothe 2008 earthquake

7 Conclusions

Paleoseismological excavations following the 2008 earth-quake show that the similar-size earthquake probably always


rupture the YBF and GJF which suggests that the centralLongmen Shan fault zone accords with a characteristicearthquake model equivalent to Mw 79 [12ndash15]

Seismic moment release indicates that the moment onthe central Longmen Shan fault zone is probably releasedby large earthquakes and the role of small and moderateearthquakes is minor Based on the characteristic seismicmoment accumulationrelease model the YBF and GJFaccommodate a moment accumulation rate of (27 plusmn 03)times 1017Nmyr and theMw79 earthquake needs an interval of

3900 plusmn 400 yrs to accumulate energy on the central LongmenShan fault zone

Acknowledgments

This work was completed with assistance from Instituteof Crustal Dynamics China Earthquake AdministrationResearch Fund (Grant ZDJ2013-23) and the National ScienceFoundation of China (Grant 41102134) The authors thankHuang Yuan and Zheng Yong for sharing relocated aftershockdata

References

[1] R S Yeats K Sieh and C R AllenTheGeology of EarthquakesOxford University Press New York NY USA 1997

[2] J McCalpin Paleoseismology Academic Press 2009[3] P-Z Zhang X-Z Wen Z-K Shen and J-H Chen ldquoOblique

high-angle listric-reverse faulting and associated developmentof strain the wenchuan earthquake of may 12 2008 sichuanChinardquo Annual Review of Earth and Planetary Sciences vol 38pp 351ndash380 2010

[4] X Xu X Wen G Yu et al ldquoCoseismic reverse- and oblique-slip surface faulting generated by the 2008 Mw 79 Wenchuanearthquake Chinardquo Geology vol 37 no 6 pp 515ndash518 2009

[5] B C Burchfiel L H Royden R D van der Hilst et al ldquoA geo-logical and geophysical context for theWenchuan earthquake of12 May 2008 Sichuan Peoplersquos Republic of Chinardquo GSA Todayvol 18 no 7 pp 4ndash11 2008

[6] Z-K Shen J Sun P Zhang et al ldquoSlip maxima at faultjunctions and rupturing of barriers during the 2008 WenchuanearthquakerdquoNature Geoscience vol 2 no 10 pp 718ndash724 2009

[7] X-W Xu G-H Chen G-H Yu et al ldquoReevaluation of surfacerupture parameters of the 5 sdot 12 wenchuan earthquake andits tectonic implication for tibetan upliftrdquo Chinese Journal ofGeophysics vol 53 no 10 pp 2321ndash2336 2010

[8] X Xu G Yu G Chen et al ldquoParameters of coseismic reverse-and oblique-slip surface ruptures of the 2008 Wenchuan earth-quake Eastern Tibetan Plateaurdquo Acta Geologica Sinica vol 83pp 673ndash684 2009

[9] R J Zhou Y Li A L Densmore et al ldquoActive tectonics of theLongmen Shan region on the eastern margin of the Tibetanplateaurdquo Acta Geologica Sinica vol 81 pp 593ndash604 2007

[10] Y Li R Zhou A L Densmore and M A Ellis ContinentalDynamics and Geological Responses of the Eastern Marginof Qinghai-Tibetan Plateau Geological Press Beijing China2006

[11] A L Densmore M A Ellis Y Li R Zhou G S Hancock andN Richardson ldquoActive tectonics of the Beichuan and Pengguan

faults at the eastern margin of the Tibetan Plateaurdquo Tectonicsvol 26 no 4 Article ID TC4005 pp 1ndash25 2007

[12] C Li W Zheng and W Wang ldquoTrenching exposures of thesurface rupture of 2008 Mw 79 Wenchuan earthquake Chinaimplications for coseismic deformation and paleoseismologyalong the Central Longmen Shan thrust faultrdquo Journal of AsianEarth Sciences vol 40 no 4 pp 825ndash843 2011

[13] A Lin Z Ren D Jia and Y Miyairi ldquoEvidence for a Tang-SongDynasty great earthquake along the Longmen ShanThrust Beltprior to the 2008Mw79Wenchuan earthquake Chinardquo Journalof Seismology vol 14 no 3 pp 615ndash628 2010

[14] Y Ran L Chen J Chen et al ldquoPaleoseismic evidence and repeattime of large earthquakes at three sites along the Longmenshanfault zonerdquo Tectonophysics vol 491 no 1ndash4 pp 141ndash153 2010

[15] Y K Ran W S Chen X W Xu et al ldquoPaleoseismic events andrecurrence interval along the Beichuan-Yingxiu fault of Long-menshan fault zone Yingxiu Sichuan Chinardquo Tectonophysicsvol 584 pp 81ndash90 2013

[16] J F Liu J Chen J H Yin et al ldquoOsl and ams14c dating of thepenultimate earthquake at the leigu trench along the beichuanfault longmen shan in the northeast margin of the tibetanplateaurdquoBulletin of the Seismological Society of America vol 100no 5 pp 2681ndash2688 2010

[17] X-ZWen P-Z Zhang F Du and F Long ldquoThe background ofhistorical andmodern seismic activities of the occurrence of the2008 Ms8 0 Wenchuan Sichuan earthquakerdquo Chinese Journalof Geophysics vol 52 no 2 pp 444ndash454 2009

[18] H Wang M Liu X Shen and J Liu ldquoBalance of seismicmoment in the Songpan-Ganze region eastern Tibet implica-tions for the 2008GreatWenchuan earthquakerdquoTectonophysicsvol 491 no 1ndash4 pp 154ndash164 2010

[19] P Molnar ldquoEarthquake recurrence intervals and plate tecton-icsrdquo Bulletin of the Seismological Society of America vol 69 pp115ndash133 1979

[20] WorkingGroup onCalifornia Earthquake Probabilities ldquoEarth-quake probabilities in the San Francisco Bay region 2002ndash2031rdquoOpen-File Report 03-214 US Geological Survey 2003

[21] T C Hanks and H Kanamori ldquoA moment magnitude scalerdquoJournal of Geophysical Research B vol 84 no 5 pp 2348ndash23501979

[22] D Jia G Wei Z Chen B Li Q Zeng and G Yang ldquoLongmenShan fold-thrust belt and its relation to the western SichuanBasin in central China new insights from hydrocarbon explo-rationrdquo AAPG Bulletin vol 90 no 9 pp 1425ndash1447 2006

[23] J Hubbard and J H Shaw ldquoUplift of the Longmen Shan andTibetan plateau and the 2008Wenchuan (M= 79) earthquakerdquoNature vol 458 no 7235 pp 194ndash197 2009

[24] J Ren G Chen X Xu S Zhang and C Mao ldquoSurfacerupture of the 2008 Wenchuan China earthquake in theqingping stepover determined from geomorphologic surveyingand excavation and its tectonic implicationsrdquo Bulletin of theSeismological Society of America vol 100 no 5 pp 2651ndash26592010

[25] J-W Teng D-H Bai H Yang et al ldquoDeep processes anddynamic responses associated with theWenchuanMS80 earth-quake of 2008rdquo Chinese Journal of Geophysics vol 51 no 5 pp1385ndash1402 2008

[26] Y Zheng H S Ma J Lu S D Ni Y C Li and S J Wei ldquoSourcemechanism of strong aftershocks (M

119904ge 56) of the 20080512

Wenchuan earthquake and the implication for seismotectonicsrdquoScience in China D vol 52 no 6 pp 739ndash753 2009


[27] J Ren S Zhang BMa andQ Tian ldquoCharacteristics and recur-rence intervals of large earthquakes along the middle-northernsegment of the Longmenshan fault zonerdquo Acta SeismologicaSinica vol 31 no 2 pp 160ndash171 2009 (Chinese)

[28] Y Huang J P Wu T Z Zhang and D N Zhang ldquoRelocationof theM80Wenchuan earthquake and its aftershock sequencerdquoScience in China D vol 51 no 12 pp 1703ndash1711 2008

[29] E Hauksson and P Shearer ldquoSouthern California hypocenterrelocation with waveform cross-correlation part 1 results usingthe double-difference methodrdquo Bulletin of the SeismologicalSociety of America vol 95 no 3 pp 896ndash903 2005

[30] J Hubbard J H Shaw and Y Klinger ldquoStructural setting ofthe 2008 Mw 79 Wenchuan China earthquakerdquo Bulletin of theSeismological Society of America vol 100 no 5 pp 2713ndash27352010

[31] D Jia Y Li A Lin et al ldquoStructural model of 2008 Mw 79Wenchuan earthquake in the rejuvenated Longmen Shan thrustbelt Chinardquo Tectonophysics vol 491 no 1ndash4 pp 174ndash184 2010

[32] Y Klinger M Le Beon B Meade and E Hetland ldquoFromgeodesy to geological similar slip rates at different time scalesthe Dead Sea Fault example (Invited)rdquo in Proceedings of theAmerican Geophysical Union Fall Meeting San Francisco CalifUSA 2010

[33] R V Sharp ldquoVariable rates of late Quaternary strike slip onthe San Jacinto fault zone southern Californiardquo Journal ofGeophysical Research vol 86 no 3 pp 1754ndash1762 1981

[34] K Blisniuk T Rockwell L A Owen et al ldquoLate Quaternaryslip rate gradient defined using high-resolution topographyand10Be dating of offset landforms on the southern San JacintoFault zone Californiardquo Journal of Geophysical Research B vol115 no 8 Article ID B08401 2010

[35] A Hampel T Karow G Maniatis and R Hetzel ldquoSlip ratevariations on faults during glacial loading and post-glacialunloading implications for the viscosity structure of the litho-sphererdquo Journal of the Geological Society vol 167 no 2 pp 385ndash399 2010

[36] X-P Yang A Li B-J Liu et al ldquoSurface deformation inthe Chengdu plain area produced by the Wenchuan Ms8 0earthquake of 12 may 2008 Sichuan Chinardquo Chinese Journal ofGeophysics vol 52 no 10 pp 2527ndash2537 2009

[37] H L He Z YWei F Shi andH Y Sun ldquoNear-field postseismicdeformation along the rupture of 2008 Wenchuan earthquakeand its implicationsrdquo Chinese Science Bulletin vol 55 no 23pp 2535ndash2541 2010

[38] Y Wan and Z-K Shen ldquoStatic Coulomb stress changes onfaults caused by the 2008Mw79Wenchuan China earthquakerdquoTectonophysics vol 491 no 1ndash4 pp 105ndash118 2010

[39] Z-K Shen J Lu M Wang and R Burgmann ldquoContemporarycrustal deformation around the southeast borderland of theTibetan Plateaurdquo Journal of Geophysical Research B vol 110 no11 Article ID B11409 pp 1ndash17 2005

[40] J Noller J Sowers and W Lettis Quaternary Geochronol-ogy Methods and Applications American Geophysical UnionWashington DC USA 2000

[41] S B Delong G E Hilley M J Rymer and C Prentice ldquoFaultzone structure from topography signatures of en echelon faultslip at Mustang Ridge on the San Andreas Fault MontereyCounty Californiardquo Tectonics vol 29 no 5 Article ID TC50032010

[42] D P Schwartz and K J Coppersmith ldquoFault behavior andcharacteristic earthquakes examples from theWasatch and San

Andreas fault zones (USA)rdquo Journal of Geophysical Researchvol 89 no 7 pp 5681ndash5698 1984

[43] SSB Division of Earthquake Monitoring and PredictionCatalog of ChineseHistorical Strong Earthquakes (2300 BC-1911)Seismological Press Beijing China 1995

[44] S J Gale ldquoDating the recent pastrdquo Quaternary Geochronologyvol 4 no 5 pp 374ndash377 2009

[45] JWallinga ldquoOptically stimulated luminescence dating of fluvialdeposits a reviewrdquo Boreas vol 31 no 4 pp 303ndash322 2002

[46] B-Q Ma G Su Z-H Hou and S-B Shu ldquoLate Quaternaryslip rate in the central part of the Longmenshan Fault zone fromterrace deformation along the Minjiang Riverrdquo Seismology andGeology vol 27 no 2 pp 235ndash242 2005 (Chinese)

[47] W Gan P Zhang Z-K Shen et al ldquoPresent-day crustal motionwithin the Tibetan Plateau inferred from GPS measurementsrdquoJournal of Geophysical Research B vol 112 no 8 Article IDB08416 2007

Submit your manuscripts athttpwwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

ClimatologyJournal of

EcologyInternational Journal of


EarthquakesJournal of


Hindawi Publishing Corporationhttpwwwhindawicom

Applied ampEnvironmentalSoil Science

Volume 2014

Mining


Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

International Journal of

Geophysics

OceanographyInternational Journal of


Journal of Computational Environmental SciencesHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal ofPetroleum Engineering


GeochemistryHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Atmospheric SciencesInternational Journal of


OceanographyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Advances in


MineralogyInternational Journal of


MeteorologyAdvances in

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Paleontology JournalHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014


Geological ResearchJournal of


Geology Advances in


998771

998771

998771

998771

998771

998771

998771

998771

998771

998771

998771

998771

Sa

Sb

Sc

Sd

Se

Sf

Sg

Hangwang

Pingwu

PingtongGuixi

Nanba

Pengzhou

Shifang

Mianzhu

Heishui

Chengdu

Mianyuan R

Minjiang R

Minjiang R

Fujiang R

T

LG Jiangyou

Anxian

Mianyang

BC

QC

QCF

YX

MX

Lixian

DJY

WCWMF

0 2010

SC

Sichuan

Basin

Orodos

Indian Plate

Tarim Basin

MSF

HYF

QP

XYDBL

GJFYBF

Tibetan Plateau

0

Main shock

Trench location

Place name

Surface rupture

Active faultRiverFocal sectionBorder of fault model

Focal mechanismBlind fault

998771

aftershock

T

6070

II

I

III

Alti

tude

(m)

ATF

KFHF

XF

JLF

RF

Saga

ing

Himalayas

20

10

0

Foca

l dep

th (k

m)

YBF GJF

40(km)

minus150

940

A

A-A998400

A998400

105∘E104

∘E103∘E

33∘N

32∘N

31∘N

Mlt5Mge5

A A998400

(km)

Figure 1 Tectonic settings and aftershock sequence of the 2008 Wenchuan earthquake Surface rupture is modified from [4] focalmechanisms are from USGS aftershock sequence is from relocated results [28] Borders of fault model are according to GPS and InSARinversion [6] Trench sites are from published results [12ndash14] White circles are place names BC Beichuan county BL Bailu town DJYDujiangyan city LG Leigu town MX Maoxian county QC Qingchuan county QP Qingping town WC Wenchuan county XYDXiaoyudong town YX Yingxiu town Black solid lines are known faults YBF Yingxiu-Beichuan fault GJF Guanxian-Jiangyou fault WMFWenchuan-Maoxian fault QCF Qingchuan fault MSF Minshan fault HYF Huya fault Insert map shows the topography of the Tibetanplateau Inset map shows major tectonics in the Longmen Shan vicinity ATF Altyn Tagh fault HF Haiyuan fault JLF Jiali fault KF Kunlunfault RF Red River fault XF Xiaoshuihe fault I Qaidam-Qilian block II Bayan Har block III Sichuan-Yunan block Black arrows indicateblock motion direction

of 2300ndash3300 yrs [14 15]The trenches of Li et al at PingtongGuixi and Nanba towns from optically stimulated lumines-cence (OSL) and radiocarbon dating revealed a sim11000 yrinterval [12] Liu et al advised a recurrence interval of 1100ndash2100 yrs in the Leigu trench utilizing OSL and radiocarbondating [16] However Wen et al recommended that therecurrence interval of large earthquakes in and adjacent tothe 2008 epicenter area is longer than 2000 yrs according tohistorical earthquake activity [17]

Significant discrepancies between these results confusethe public that which value is preferred for large earthquakeon the Longmen Shan fault zone In this paper we construct a

characteristic seismic moment accumulationrelease modelbased on fault geometry of the seismogenic zone and estimatethe average recurrence interval of earthquakes similar to the2008 shock along the central Longmen Shan fault zone

2 Characteristic Seismic MomentAccumulationRelease Model

Seismic activity is a process of energy accumulation andrelease [18] Seismic moment is a measure of the size of anearthquake in terms of the energy released and is associated







119879 =1198720

1198720

(1)



119908) using the




1198720119904= 120583119860] (2)



119860 = 119871119882119877 (3)




1198720119904=120583119871119867119877]

sin (120579) (4)


1198720= sum119872

0119904 (5)


W

H

Base of seismogenic

zone


segment 2

Segment 1 Segment 2


L120579








11990450 based on




Log1198720= 16119872

119904+ 80 (6)



45 5 55 6 65 7 75 8 85


2008 earthquake

Ms

(Nm

)M

0

1e+15

1e+16

1e+17

1e+18

1e+19

1e+20

1e+21

1e+22

LogM0 = 16 Ms + 80






11990450

191311987211990450 1958119872

11990462 and 1999119872

















SaSb

ScSd

SeSf

Sg

33 1031035

1041045

1051055

106

02040

325 32 315 31 305

Dep

th(k

m)

QingchuanNanba

Beichuan

YingxiuGJFN

Latitude (∘N)

Long

itude

(∘ E)

96∘

56∘

49∘49∘

44∘

43∘

43∘

28∘50∘

(a)

0 10 20 30

Afte

rsho

ck n

umbe

r

0

20

40

60

80


Focal depth (km)


(b)

Afte

rsho

ck n

umbe

r

010203040506070

Aftershock num 417



(c)

Afte

rsho

ck n

umbe

r

05

101520253035

Aftershock num 627



(d)

Afte

rsho

ck n

umbe

r

05

101520253035

Aftershock num 148


Preferred mean 15km

(e)

Afte

rsho

ck n

umbe

r

0

20

40

60

80

100



(f)

Afte

rsho

ck n

umbe

r

05

10152025303540

Aftershock num 211



(g)




















7 Conclusions






Acknowledgments


References




























119904ge 56) of the 20080512


































Volume 2014

Mining


Journal of



Geophysics







Journal of




Advances in











Geology Advances in







119879 =1198720

1198720

(1)



119908) using the




1198720119904= 120583119860] (2)



119860 = 119871119882119877 (3)




1198720119904=120583119871119867119877]

sin (120579) (4)


1198720= sum119872

0119904 (5)


W

H

Base of seismogenic

zone


segment 2

Segment 1 Segment 2


L120579








11990450 based on




Log1198720= 16119872

119904+ 80 (6)



45 5 55 6 65 7 75 8 85


2008 earthquake

Ms

(Nm

)M

0

1e+15

1e+16

1e+17

1e+18

1e+19

1e+20

1e+21

1e+22

LogM0 = 16 Ms + 80






11990450

191311987211990450 1958119872

11990462 and 1999119872

















SaSb

ScSd

SeSf

Sg

33 1031035

1041045

1051055

106

02040

325 32 315 31 305

Dep

th(k

m)

QingchuanNanba

Beichuan

YingxiuGJFN

Latitude (∘N)

Long

itude

(∘ E)

96∘

56∘

49∘49∘

44∘

43∘

43∘

28∘50∘

(a)

0 10 20 30

Afte

rsho

ck n

umbe

r

0

20

40

60

80


Focal depth (km)


(b)

Afte

rsho

ck n

umbe

r

010203040506070

Aftershock num 417



(c)

Afte

rsho

ck n

umbe

r

05

101520253035

Aftershock num 627



(d)

Afte

rsho

ck n

umbe

r

05

101520253035

Aftershock num 148


Preferred mean 15km

(e)

Afte

rsho

ck n

umbe

r

0

20

40

60

80

100



(f)

Afte

rsho

ck n

umbe

r

05

10152025303540

Aftershock num 211



(g)




















7 Conclusions






Acknowledgments


References




























119904ge 56) of the 20080512


































Volume 2014

Mining


Journal of



Geophysics







Journal of




Advances in











Geology Advances in


45 5 55 6 65 7 75 8 85


2008 earthquake

Ms

(Nm

)M

0

1e+15

1e+16

1e+17

1e+18

1e+19

1e+20

1e+21

1e+22

LogM0 = 16 Ms + 80






11990450

191311987211990450 1958119872

11990462 and 1999119872

















SaSb

ScSd

SeSf

Sg

33 1031035

1041045

1051055

106

02040

325 32 315 31 305

Dep

th(k

m)

QingchuanNanba

Beichuan

YingxiuGJFN

Latitude (∘N)

Long

itude

(∘ E)

96∘

56∘

49∘49∘

44∘

43∘

43∘

28∘50∘

(a)

0 10 20 30

Afte

rsho

ck n

umbe

r

0

20

40

60

80


Focal depth (km)


(b)

Afte

rsho

ck n

umbe

r

010203040506070

Aftershock num 417



(c)

Afte

rsho

ck n

umbe

r

05

101520253035

Aftershock num 627



(d)

Afte

rsho

ck n

umbe

r

05

101520253035

Aftershock num 148


Preferred mean 15km

(e)

Afte

rsho

ck n

umbe

r

0

20

40

60

80

100



(f)

Afte

rsho

ck n

umbe

r

05

10152025303540

Aftershock num 211



(g)




















7 Conclusions






Acknowledgments


References




























119904ge 56) of the 20080512


































Volume 2014

Mining


Journal of



Geophysics







Journal of




Advances in











Geology Advances in


SaSb

ScSd

SeSf

Sg

33 1031035

1041045

1051055

106

02040

325 32 315 31 305

Dep

th(k

m)

QingchuanNanba

Beichuan

YingxiuGJFN

Latitude (∘N)

Long

itude

(∘ E)

96∘

56∘

49∘49∘

44∘

43∘

43∘

28∘50∘

(a)

0 10 20 30

Afte

rsho

ck n

umbe

r

0

20

40

60

80


Focal depth (km)


(b)

Afte

rsho

ck n

umbe

r

010203040506070

Aftershock num 417



(c)

Afte

rsho

ck n

umbe

r

05

101520253035

Aftershock num 627



(d)

Afte

rsho

ck n

umbe

r

05

101520253035

Aftershock num 148


Preferred mean 15km

(e)

Afte

rsho

ck n

umbe

r

0

20

40

60

80

100



(f)

Afte

rsho

ck n

umbe

r

05

10152025303540

Aftershock num 211



(g)




















7 Conclusions






Acknowledgments


References




























119904ge 56) of the 20080512


































Volume 2014

Mining


Journal of



Geophysics







Journal of




Advances in











Geology Advances in













7 Conclusions






Acknowledgments


References




























119904ge 56) of the 20080512


































Volume 2014

Mining


Journal of



Geophysics







Journal of




Advances in











Geology Advances in





Acknowledgments


References




























119904ge 56) of the 20080512


































Volume 2014

Mining


Journal of



Geophysics







Journal of




Advances in











Geology Advances in

































Volume 2014

Mining


Journal of



Geophysics







Journal of




Advances in











Geology Advances in










Volume 2014

Mining


Journal of



Geophysics







Journal of




Advances in











Geology Advances in

Estimation of recurrence interval of large earthquakes on the central Longmen Shan fault zone based on seismic moment accumulation/release model

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