Rupture process of the M _s 7.0 Lushan earthquake determined by joint inversion of local static GPS records, strong motion data, and teleseismograms

Abstract

On April 20, 2013, an M _s 7.0 earthquake struck Lushan County in Sichuan Province, China, and caused serious damage to the source region. We investigated the rupture process of the Ms7.0 Lushan earthquake by jointly inverting waveforms of teleseismic P waveforms and local strong motion records as well as static GPS observations. The inverted results indicate that the rupture of this earthquake was dominated by the failure of an asperity with a triangular shape and that the main shock was dominated by thrust slip. The earthquake released a total seismic moment of 1.01×10¹⁹ Nm, with 92% of it being released during the first 11 s. The rupture had an average slip of 0.9 m and produced an average stress drop of 1.8 MPa. Compared with our previous work that was based mainly on a unique dataset, this joint inversion result is more consistent with field observations and the distribution of aftershock zones.

Keywords

GPS / Longmenshan / Lushan Earthquake / rupture process / strong motion

References

[1] Allmann B. P., Shearer P. M. Global Variations of Stress Drop for Moderate to Large Earthquakes. Journal of Geophysical Research: Solid Earth, 2009, 114(B1): 1310-1321.

[2] Chen G. G., Ji F. J., Zhou R. J., . Primary Research of Activity Segmentation of Longmenshan Fault Zone since Late Quaternary. Seismology Geology, 2007, 29(3): 657-673.

[3] Chen L. C., Wang H., Ran Y. K., . The M _s 7. 1 Yushu Earthquake Surface Rupture and Large Historical Earthquakes on the Garzê-Yushu Fault. Chinese Science Bulletin, 2010, 55(31): 3504-3509.

[4] Gao Y., Wang Q., Zhao B., . A Rupture Blank Zone in Middle South Part of Longmenshan Faults: Effect after Lushan M _s 7.0 Earthquake of 20 April in Sichuan, China. Science China: Earth Sciences, 2013, 57(9): 2036-2041.

[5] Hao J. L., Ji C., Wang W. M., . Rupture History of the 2013 M _w 6.6 Lushan Earthquake Constrained with Local Strong Motion and Teleseismic Body and Surface Waves. Geophysical Research Letters, 2013, 40(20): 5371-5376.

[6] Huang Y., Wu J. P., Zhang T. Z., . Re-Determination of the Large Wenchuan Earthquake (M _s 8.0) and Its Sequence of Aftershocks. Science China Series D: Earth Science, 2008, 38(10): 1242-1249.

[7] Ji C., Helmberger D. V., Song A., . Slip Distribution and Tectonic Implication of the 1999 Chi-Chi, Taiwan, Earthquake. Geophysical Research Letters, 2001, 28(23): 4379-4382.

[8] Ji C., Wald D. J., Helmberger D. V., . Source Description of the 1999 Hector Mine, California, Earthquake, Part I: Wavelet Domain Inversion Theory and Resolution Analysis. Bulletin of the Seismological Society of America, 2002, 92(4): 1192-1207.

[9] Jiang Z. S., Wang M., Wang Y. Z., . GPS Constrained Coseismic Source and Slip Distribution of the 20 April 2013 Lushan, China, Earthquake and Its Tectonic Implications. Geophysical Research Letters, 2013, 41(2): 407-413.

[10] Kanamori H., Anderson D. L. Theoretical Basis of Some Empirical Relations in Seismology. Bulletin of the Seismological Society of America, 1975, 65: 1073-1095.

[11] Liu C. L., Shan B., Zheng Y., . Modeling of Co-and Post-Seismic Surface Deformation and Gravity Changes of M _W 6.9 Yushu, Qinghai, Earthquakes. Earthquake Science, 2011, 24(2): 177-183.

[12] Liu C. L., Zheng Y., Ge C., . Rupture Process of the M _s 7.0 Lushan Earthquake. Science China: Earth Sciences, 2013, 56(7): 1187-1190.

[13] Liu M. J., Wang F. Y., Jia S. X., . Jianganlin Surface Fracture Induced by 2013 Lushan M _s 7.0 Earthquake. Acta Seismologica Sinica, 2014, 36(1): 129-138.

[14] Liu Q. Y., Li Y., Chen J. H., . Wenchuan^M _s 8.0 Earthquake: Preliminarystudy of the S-Wave Velocity Structure of the Crust and Uppermantle. Chinese Journal of Geophysics, 2009, 52(2): 309-319.

[15] Lü J., Wang X. S., Miao C. L., . On Characteristics of Hypocenter Distribution and Rupture Complexity of Wenchuan Aftershock Sequence along Longmenshan Fault Zone North to Beichuan. Journal of Geodynamics, 2012, 32(5): 17-21.

[16] Shan B., Xiong X., Zheng Y., . Stress Changes on Major Faults Caused by M _w 7.9 Wenchuan Earthquake, May 12, 2008. Science China Series D: Earth Science, 2009, 52(5): 593-601.

[17] Shan B., Xiong X., Zheng Y., . Stress Changes on Major Faults Caused by 2013 Lushan Earthquake, and Its Relationship with 2008 Wenchuan Earthquake. Science China: Earth Science, 2013, 56(7): 1169-1174.

[18] Shen Z. K., Sun J., Zhang P., . Slip Maxima at Fault Junctions and Rupturing of Barriers During the 2008 Wenchuan Earthquake. Nature Geosciences, 2009, 2(10): 718-724.

[19] Subarya C., Chlieh M., Prawirodirdjo L., . Plate-Boundary Deformation Associated with the Great Sumatra–Andaman Earthquake. Nature, 2006, 440(7080): 46-51.

[20] Wald D. J., Heaton T. H. The Slip History of the 1994 Northridge, California, Earthquake Determined from Strong Motion, Teleseismic, GPS, and Leveling Data. Bulletin of the Seismological Society of America, 1996, 86: S49-S70.

[21] Wang C. Y., Wu J. P., Lou H., . P-Wave Crustal Structure in Westernsichuan and Eastern Tibetan Region. Science China Series D: Earth Science, 2003, 46: 254-265.

[22] Wang K., Liu C. L., Xiong X., . Co-and Post-Seismic Surface Deformation and Gravity Changes of M _s 7.0 Lushan Earthquake. Earthquake Science, 2013, 26(3–4): 207-213.

[23] Wang W. M., Hao J. L., Yao Z. X., . Preliminary Result for Rupture Process of Apr. 20, 2013, Lushan Earthquake, Sichan, China. Chinese Journal of Geophysics, 2013, 56(4): 1421-1417.

[24] Wei S. J., Fielding E., Leprince S., . Superficial Simplicity of the 2010 El Mayor-Cucapah Earthquake of Baja California in Mexico. Nature Geosciences, 2011, 4(9): 615-618.

[25] Wu Y. Q., Jiang Z. S., Wang M., . Preliminary Results of the Co-Seismic Displacement and Pre-Seismic Strain Accumulation of the Lushan M _s 7.0 Earthquake Reflected By the GPS Surveying. Chinese Science Bulletin, 2013, 58(28–29): 3460-3466.

[26] Xie Z. J., Jin B. K., Zheng Y., . Source Parameters Inversion of the 2013 Lushan Earthquake by Combining Teleseismic Waveforms and Local Seismograms. Science China: Earth Science, 2013, 23(6): 1020-1026.

[27] Xu C., Xu X. W., Tian Y. Y., . Two Comparable Earthquakes Produced Greatly Different Coseismic Landslides: The 2015 Gorkha, Nepal and 2008 Wenchuan, China Events. Journal of Earth Science, 2016, 27(6): 1008-1015.

[28] Yang X. Y., Zeng W. H., Wang Y., . Numerical Simulation on Magnitude 7 or over Earthquakes in Southeast Gansu Province and Its Neighboring Areas. Earth Science, 2016, 41(7): 1231-1237.

[29] Zeng X. F., Luo Y., Han L., . The Lushan M _s7.0 Earthquake on 20 April 2013: A High-Angle Thrust Event. Chinese Journal of Geophysics, 2013, 56: 1418-1424.

[30] Zhang Y., Wang R., Chen Y., . Kinematic Rupture Model and Hypocenter Relocation of the 2013 M _w 6.6 Lushan Earthquake Constrained by Strong-Motion and Teleseismic Data. Geophysical Research Letters, 2014, 85(1): 15-22.

[31] Zhang Y., Xu L. S., Chen Y. T., . Rupture Process of the Lushan 4.20 Earthquake and Preliminary Analysis on the Disaster-Causing Mechanism. Chinese Journal of Geophysics, 2013, 56(4): 1408-1411.

[32] Zhao B., Gao Y., Huang Z. B., . Double Difference Relocation, Focal Mechanism and Stress Inversion of Lushan M _s 7.0 Earthquake Sequence. Chinese Journal of Geophysics, 2013, 56(10): 3385-3396.

[33] Zhao Z., Fan J., Zheng S. H., . Crustal Velocity Structure of Thelongmen Shan Fault Zone and Source Location Accurate Revision. Acta Seismologica Sinica, 1997, 19: 6l5-622.

[34] Zheng Y., Ge C., Xie Z. J., . Crustal and Upper Mantle Structure and the Deep Seismogenic Environment in the Source Regions of the Lushan Earthquake and the Wenchuan Earthquake. Science China: Earth Science, 2013, 56(7): 1158-1168.

[35] Zhou S. Y., Kojiro I., Cheng X. F., . Analysis of the Reliability and Resolution of the Earthquake Source History Inferred from Waveforms, Taking the Chi-Chi Earthquake as an Example. Geophysical Journal International, 2004, 157(3): 1217-1232.

[36] Zhu J. S. The Wenchuan Earthquake Occurrence Background in Deepstructure and Dynamics of Lithosphere. Journal of Chengdu Univeristy of Technology (Science &Technology Edition), 2008, 35(4): 348-356.