Coseismic Slip Distribution of the 2021 Mw7.4 Maduo, Qinghai Earthquake Estimated from InSAR and GPS Measurements

Abstract

On 22 May 2021, the Maduo Earthquake occurred on a branch fault of the East Kunlun fault in the Bayan Har Block, which provides opportunity to constrain fault geometry and strain accumulation and release for assessment of earthquake hazards. We processed the Sentinal-1A/B SAR images acquired before and after the earthquake, with which we constrained a finite fault model to best fit to the combined data set of downsampled InSAR image and GPS displacements. The inversion indicates that the Maduo event ruptured a 160 km long section striking 286.5° and a dipping 81.39° with rake angle of 4.62°. The model suggests three compact rupture areas with the slip amplitude exceeding 4 m on the main rupture section and the largest slip region is in the east of the epicenter with a slip of approximately 4.6 m below the surface, in a good agreement with the field geological survey. The total geodetic moment is 1.67 × 10²⁰ N·m equivalent to Mw7.44, slightly larger than estimate of the USGS.

Keywords

Maduo Earthquake / geodetic measurements / coseismic displacements / slip distribution / focal mechanism / earthquakes

References

[1] Chen C W, Zebker H A. Phase Unwrapping for Large SAR Interferograms: Statistical Segmentation and Generalized Network Models. IEEE Transactions on Geoscience and Remote Sensing, 2002, 40(8): 1709-1719.

[2] Chen H, Qu C Y, Zhao D Z, . Rupture Kinematics and Coseismic Slip Model of the 2021 Mw 7.3 Maduo (China) Earthquake: Implications for the Seismic Hazard of the Kunlun Fault. Remote Sensing, 2021, 13(16): 3327

[3] Deng Q D, Gao X, Chen G H. Recent Tectonic Activity of Bayankala Fault-Block and the Kunlun-Wenchuan Earthquake Series of the Tibetan Plateau. Earth Science Frontiers, 2010, 17 5 163-178

[4] Deng Q D, Zhang P Z, Ran Y K, . Basic Characteristics of Active Tectonics of China. Science in China Series D: Earth Sciences, 2003, 46(4): 356-372.

[5] Farr T G, Rosen P A, Caro E, . The Shuttle Radar Topography Mission. Reviews of Geophysics, 2007, 45(2): RG2004

[6] Gao X, Deng Q D. Activity Analysis of Large Earthquakes in Boundary Faults around the Bayankala Faulting Block. Acta Geologica Sinica, 2013, 87 1 9-19. (in Chinese with English Abstract)

[7] Hanssen R F. Radar Interferometry Data Interpretation and Error Analysis, 2001, Dordrecht: Springer

[8] Huang Y, Qiao X J, Freymueller J T, . Fault Geometry and Slip Distribution of the 2013 Mw 6.6 Lushan Earthquake in China Constrained by GPS, InSAR, Leveling, and Strong Motion Data. Journal of Geophysical Research: Solid Earth, 2019, 124(7): 7341-7353.

[9] Lasserre C, Peltzer G, Crampé F, . Coseismic Deformation of the 2001 Mw = 7.8 Kokoxili Earthquake in Tibet, Measured by Synthetic Aperture Radar Interferometry. Journal of Geophysical Research Atmospheres, 2005, 110(B12): 408

[10] Li M K, Zhang S X, Zhang C Y, . Fault Slip Model of 2013 Lushan Earthquake Retrieved Based on GPS Coseismic Displacements. Journal of Earth Science, 2015, 26 4 537-547.

[11] Li Z C, Ding K H, Zhang P, . Coseismic Deformation and Slip Distribution of 2021 Mw7.4 Maduo Earthquake from GNSS Observation. Geomatics and Information Science of Wuhan University, 2021, 46(10): 1489-1497. (in Chinese with English Abstract)

[12] Li Z H, Elliott J R, Feng W P, . The 2010 Mw6.8 Yushu (Qinghai, China) Earthquake: Constraints Provided by InSAR and Body Wave Seismology. Journal of Geophysical Research Atmospheres, 2011, 116(B10): 302

[13] Lin A M, Fu B H, Guo J M, . Co-Seismic Strike-Slip and Rupture Length Produced by the 2001 Ms 8.1 Central Kunlun Earthquake. Science, 2002, 296 5575 2015-2017.

[14] Liu G, Xiong W, Wang Q, . Source Characteristics of the 2017 Ms 7.0 Jiuzhaigou, China, Earthquake and Implications for Recent Seismicity in Eastern Tibet. Journal of Geophysical Research: Solid Earth, 2019, 124(6): 4895-4915.

[15] Liu X W, Yuan D Y, Su Q, . Late Quaternary Tectonic Activity and Slip Rates of Active Faults in the Western Hexi Corridor, NW China. Journal of Earth Science, 2020, 31(5): 968-977.

[16] Okada Y. Surface Deformation Due to Shear and Tensile Faults in a Half-Space. Bulletin of the Seismological Society of America, 1985, 75(4): 1135-1154.

[17] Pan J W, Bai M K, Li C, . Coseismic Surface Rupture and Seismogenic Structure of the 2021-05-22 Maduo (Qinghai) Ms7.4 Earthquake. Acta Geologica Sinica, 2021, 95(6): 1655-1670. (in Chinese with English Abstract)

[18] Qin X H, Tan C X, Chen Q C, . Crustal Stress State and Seismic Hazard along Southwest Segment of the Longmenshan Thrust Belt after Wenchuan Earthquake. Journal of Earth Science, 2014, 25(4): 676-688.

[19] Wang D, Mori J. The 2010 Qinghai, China, Earthquake: A Moderate Earthquake with Supershear Rupture. Bulletin of the Seismological Society of America, 2012, 102(1): 301-308.

[20] Wang D, Takeuchi N, Kawakatsu H, . Estimating High Frequency Energy Radiation of Large Earthquakes by Image Deconvolution Back-Projection. Earth and Planetary Science Letters, 2016, 449: 155-163.

[21] Wang Q, Qiao X J, Lan Q G, . Rupture of Deep Faults in the 2008 Wenchuan Earthquake and Uplift of the Longmen Shan. Nature Geoscience, 2011, 4(9): 634-640.

[22] Wang W L, Fang L H, Wu J P, . Aftershock Sequence Relocation of the 2021 M _S7.4 Maduo Earthquake, Qinghai, China. Science China Earth Sciences, 2021, 64(8): 1371-1380.

[23] Wen X Z, Du F Y, Zhang Z, . Correlation of Major Earthquake Sequences on the Northern and Eastern Boundaries of the Bayan Har Block, and Its Relation to the 2008 Wenchuan Earthquake. Chinese Journal of Geophysics: Chinese Edition, 2011, 54(3): 706-716. (in Chinese with English Abstract)

[24] Xu X W, Wen X Z, Chen G H, . Discovery of the Longriba Fault Zone in the Eastern Part of the Yakala Block and Its Tectonic Significance. Science in China Series D: Earth Sciences, 2008, 38(5): 529-542. (in Chinese with English Abstract)

[25] Yan Y, Pinel V, Trouvé E, . Coseismic Displacement Field and Slip Distribution of the 2005 Kashmir Earthquake from SAR Amplitude Image Correlation and Differential Interferometry. Geophysical Journal International, 2013, 193(1): 29-46.

[26] Yu M Y, Yu C Q, Qu C, . Deep Structural Characteristics of Pengguan Complex in Longmenshan Fault Zone Derived from Seismic Reflective Profile. Earth Science, 2021, 46(5): 1737-1748. (in Chinese with English Abstract)

[27] Zhang P Z, Deng Q D, Zhang G M, . Active Tectonic Blocks and Strong Earthquakes in the Continent of China. Science in China Series D: Earth Sciences, 2003, 46(2): 13-24

[28] Zhao D Z, Qu C Y, Chen H, . Tectonic and Geometric Control on Fault Kinematics of the 2021 Mw7.3 Maduo (China) Earthquake Inferred from Interseismic, Coseismic, and Postseismic InSAR Observations. Geophysical Research Letters, 2021, 48 18 e2021GL095417