section_path: Earthquake
section_name: Earthquake
paragraph_text: Earthquake
  
  The United States Geological Survey noted that the earthquake measured a moment magnitude (M) of 7.1, while the China Earthquake Networks Center documented its magnitude at M 6.8. The shock occurred at 10 km (6.2 mi) depth, indicating it occurred within the continental crust that forms the Tibetan Plateau. It was caused by normal faulting with a minor strike-slip component. Focal mechanism solutions indicate that the rupture occurred on a north-south striking fault, dipping moderately to either the east or west. The epicentre was at Tsogo Township in Tingri County, an area with an average altitude of 4,500 m (14,800 ft).
  
  Modelling of the rupture by the United States Geological Survey revealed motion along a north–northeast striking fault dipping west–northwest or north–northwest striking fault dipping east–northeast. In both solutions, co-seismic slip occurred for about 80 km (50 mi) along strike and extended to 20 km (12 mi) depth. The maximum slip in these solutions were 1.6 m (5 ft 3 in) and 1.3 m (4 ft 3 in), respectively. A rupture area of about 80 km (50 mi) x 20 km (12 mi) was estimated, extending from Ngamring County to southern Tingri County near the border with Nepal. Seismologists at the China Earthquake Networks Center said the mainshock originated within the Lhasa terrane, a crustal block that forms part of the plateau.
  
  InSAR analysis of before and after images from the European Space Agency Sentinel 1A satellite shows evidence of subsidence to the west of the surface rupture and uplift to the east. Combined with the observed focal mechanism, these observations confirm that this earthquake was caused by normal faulting on a west- dipping fault. The causative fault has been identified as the Deng Me Cuo Fault.
  
  The China Earthquake Administration evaluated that the entire rupture occurred within 24 seconds, releasing a seismic moment estimated at 4.0469 × 10 19 Nm. The greatest moment release occurred 14 seconds after the rupture initiated. The rupture propagated bilaterally along a normal fault, but most of it was directed northward. Remote sensing and ground surveys indicated a surface rupture of 25–32 km (16–20 mi) and maximum displacement of 3 m (9.8 ft). About 11 km (6.8 mi) of the rupture was along the eastern shore of Dengme Co Lake, where field surveysors discovered a 100 m (330 ft) wide zone of fissures and some sinistral displacement. The remaining rupture continued towards the north of the lake. The Ministry of Natural Resources projected a 50 km (31 mi) rupture extending to 16 km (9.9 mi) depth by using seismic inversion of InSAR data. Much of the coseismic slip occurred at 1 to 5 km (0.62 to 3.11 mi) depth and a maximum slip of 6 m (20 ft) was Inferred at 1 to 2 km (0.62 to 1.24 mi) depth. In Changsuo Township vertical scarps of 3 m (9.8 ft) were measured along a zone of ruptures nearly 4 km (2.5 mi) long at 5,300 to 5,500 m (17,400 to 18,000 ft) elevation.
  
  In a survey by the China Earthquake Administration, intensity VI or higher on the China seismic intensity scale was felt for more than 23,986 km 2 (9,261 sq mi) along a general north–south trend. A 411 km 2 (159 sq mi) area was assigned IX including Changsuo, Quluo, Cuoguo, Nixia and Jiacuo townships. Intensity VIII formed a band around the meizoseismal area for 869 km 2 (336 sq mi) which encompassed 8 townships. Twenty townships across Tingri, Lhazi, Dinggye, Sakya and Angren counties were within the VII isoseismal band that was assigned to a 5,350 km 2 (2,070 sq mi) area. At least 3,614 aftershocks followed the mainshock by 14 January.