7/28/2019 Seismic Source Characterisation KUNLUNFault

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MSc Geotechnics / MEng CI-452 CourseworkSeismic Source Characterisation: KUNLUN FAULT, Northern Tibet

Style of Faulting Sinistral (left-lateral) Strike Slip. Location: Northern Tibet (Figure 1).

Fault Geometry Strike: E-W (N86°E) to WNW-ESE (N105°E), Dip: 86° (Lin, A. et al 2003)

Historical Activity 1902 Ms6.9, 1937 Ms7.5 Tuosho Lake, 1947 Ms7.7, 1963 Ms7.0, 1967 Ms7.0 Alake Lake, 1973 Ms7.4 Manyi, 1997 Mw7.6 Manyi, 2001 Mw7.8 Central Kunlun.

Attribute Max. Value Min. Value Preferred Notes

Length (km)1600 155 400 The total length of ~1600km (Van Der Woerd et al, 2002) is divided into six principal segments varying from 155km

to 400km (1). Three rupture scenarios are examined (2).

Width (km)5.7 4.8 5.2 Crustal thickness at Northern Tibet considered varying from 55km to 65km. Preferred value 60km. Fault dip at 85°

(Values for Strike, Dip and Rake for the 7.8 Mw, 14Nov.2001 EQ, calculated at 96°, 86° and 7° respectively, byU.S.G.S.)

Maximum Magnitude

4.9×10+21

8.58.7

9.8×10+19

7.37.6

5.5×10+20

6.5×10+20

7.88.1

Calculated Seismic moment: Mo=μ × Α × s [N m] for slip 4m, 8m and 16.3m (Lin et al, 2006)ˑ

Seismic moment Mo from Lin., A et al., 2003 for the Mw 7.8 2001 EQ.Moment scale magnitude calculated from Mw = (2/3) × log10 (Mo) – 6, Hanks & Kanamori (1979)M=5.16 + 1.12 × log(SRL), SRL: surface rupture length, Wells and Coppersmith (1994)

 Average displ. (m)21.442.9

1,83.8

5,010.1

 AD: log(AD) = -6.32 + 0.90 × Mw, Wells and Coppersmith (1994) AD: log(AD) = -1.70 + 1.04 × log(SRL), Wells and Coppersmith (1994)

Slip Rate(mmyr -1)

57.9 4.4 12.5 Calculated for Kusai Hu segment, for 300y to 400y recurrence and moment scale magnitudes

20 10 - Kusai Hu segment, Pleistocene (Kidd and Molnar, 1988).

- - 16.4 Kusai Hu segment, last 7000y (Lin et al, 2006)

- - 11.5±2 Kunlun fault, last 40000y (Van der Woerd et al, 2000, 2002)

6 2 At the easternmost segment of the fault (Kirby et al, 2007)

Recurrence (yrs)

910 280 640 Calculated for Kusai Hu segment: for characteristic slips of 4m, 8m and 16.3m and the above calculated slip rates

850±200 Xidatan-Dongdatan segment (Van der Woerd et al, 2000)410 320 - Kusai Hu segment, last 7000y for 7.8 Mw EQs (Lin et al, 2006)

400 300 - Western part of the fault (Lin et al, 2011)

1000 800 - Eastern part of the fault (Lin et al, 2011)

Footnotes:(1) The principal segments are, from west to east: Kusai Hu, Xidatan-Dongdatan, Alag Hu, Dongxi Co, Maqen and Min Shan (Figure 1). According to Van Der Woerd et al, 2002, their lengths are 270km, 160km,

210km, 155km, 270km and 260km respectively. Surface rupture of ~400km from the Kunlun earthquake in 2001, divided further into five segments with lengths from 55km to 130km (Fu et al. 2005).(2) The first scenario considers the maximum values for total fault rupture: length, width and slip are 1600km (total length), 5.7km (width) and 16.3m (maximum observed slip). The second case considers the

minimum principal segment rupture values: 155 (smallest segment), 4.8km (width) and 3m (minimum slip). The third case (preferred) considers maximum principal segment: 400km (largest segment), 5.2km(width) and 7m slip.

References• Fu, B., Awata, Y., Du, J., Ninomiya, Y., He, W., 2005. Complex geometry and segmentation of the surface rupture associated with the 14 November 2001 great Kunlun earthquake northern Tibet, China.

Tectonophysics 407, 43-63

• Fu., B., Awata, Y., Du, J., and He, W., 2005. Late Quaternary systematic stream offsets caused by repeated large seismic events along the Kunlun fault, northern Tibet, Geomorphology, 71, 278-292

• Kidd, W.S.F. & Molnar, P., 1988. Quaternary and active faulting observed on the 1985 Academia Sinica–Royal Society geotraverse of Tibet, Phil. Trans. R. Soc. Lond., 327, 337–3363.

• Kirby,E., Harkins,N., Wang, E., Shi, X., Fan, C., and Burbank, D., 2007. Slip rate gradients along the eastern Kunlun fault, Tectonics, vol. 26, 2007• Lin, A., Nishikawa, M., 2011. Riedel shear structures in co-seismic surface rupture zone produced by the 2001 Mw 7.8 Kunlun earthquake, northern Tibetan Plateau, Journal of Structural Geology 33, 1302-

1311, Elsevier 

• Lin, A., Guo, J., Kano, K. and Awata, Y., 2006. Average Slip Rate and Recurrence Interval of Large-Magnitude Earthquakes on the Western Segment of the Strike-Slip Kunlun Fault, Northern Tibet, Bulletin of 

the Seismological Society of America, vol. 96, No. 5, pp. 1597-1611

• Lin., A., Kikuchi, M., and Fu, B., 2003. Rupture Segmentation and Process of the 2001 Mw 7.8 Central Kunlun, China, Earthquake. Bulletin of the Seismological Society of America, vol. 93, No. 6, pp. 2477-

2492

• Lin, A., Fu, B., Guo, J., Zeng, Q., Dang, G, He, W., and Zhao, Y. 2002. Co-Seismic Strike-Slip and Rupture Length Produced by the 2001 Ms 8.1 Central Kunlun Earthquake, Science, Vol. 296.

• Van der Woerd, J., Ryerson, F.J., Tapponnier, P., Meriaux, A.-S., Gaudemer, Y., Meyer, B., Finkel, R.C., Caffee, M.W., Guoguang, Z., and Zhiqin, X., 2000. Uniform Slip-Rate along the Kunlun Fault:

implications for seismic behaviour and large-scale tectonics, Geophysical Research Letters, vol. 27, No. 16, Pages 2353-2356.

• Van Der Woerd, J., Tapponnier, P., Ryerson, F.,J., Meriaux, A-S., Meyer, B., Gaudemer Y.,, Finkel, R.C., Caffee, M.W., Guoguang, Z., and Zhiqin, X., 2002. Uniform postglacial slip-rate along the central 600

km of the Kunlun Fault (Tibet), from 26Al, 10Be, and 14C dating of riser offsets, and climatic origin of the regional morphology. Geophys. J. Int. (2002) 148, 356–388

7/28/2019 Seismic Source Characterisation KUNLUNFault

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• Wen, X., Yi, G., and Xu., X., 2006, Background and precursory seismicities along and surrounding the Kunlun fault before the Ms8.1, Kokoxili earthquake, China, Journal of Asian Earth Sciences, 30, 63-72

Figure 1. Kunlun Fault principal segments are, from west to east: Kusai Hu, Xidatan-Dongdatan, Alag Hu, Dongxi Co, Maqen and Min Shan (Fu et al. 2005).