# Aerial Mapping of Coseismic Surface Rupture of 2021 M\({}_{\rm w}\) 7.3 Maduo Earthquake, China
## 5 Discussion and Conclusions  
It can be seen from the comparison of D-InSAR and drone survey results that D-InSAR shows the range of surface rupture well on the whole, which can provide guidance for field surveys. The field survey also showed that D-InSAR could not fully reflect the details. For example, it is difficult for D-InSAR to identify the branch fractures at the east and west ends, and some small fractures around the main rupture. Although the surface rupture on D-InSAR is continuous, the actual investigation showed that the surface fractures are intermittent. In some areas, the ruptures are continuous, but in some places, they are difficult to find. This shows that the investigation of an earthquake surface rupture needs to combine different investigation methods, from the whole to the part. Only in this way can we have a further understanding of the surface rupture. The development of the peaty meadow layer on the surface may be the main reason for the formation of two different fracture types in the same earthquake. Alpine meadows are commonly found throughout the Qinghai-Tibet Plateau. Especially at the foot of the mountain, the dense surficial peaty meadow layer, which has a thickness of 20-50 cm, resides on top of a layer of loose sand and gravel (Figures 8C-E and S4B), whereas on the hillside, these meadow layers are not thick, only a few centimeters (Figure S4A). Where the meadow is thin, the R shears, R\({}^{\prime}\) shears, and T fractures are distributed in disorder (Figures 4 and 5A). Where the peaty meadow layer is thick, en-echelon shears and push-ups are the main structures, and they show a more orderly distribution pattern (Figures 5B, 6 and 7). These indicate that different material compositions and mechanical properties are responsible for different fracture patterns of the surface. The sand liquefaction and sand dune distribution widely developed along the fault show that there are a large number of loose materials both underground and on the surface (Figures S5 and S6). Although the surface rupture of this earthquake is as long as 160 km, there are long gaps between successive rupture (Figure 10). Especially in the area covered by two deserts, these two areas are the longest surface rupture discontinuities, which have only a few sporadic small fractures along the fault trace. When the D-InSAR result shows that there is deformation on both sides of the discontinuities (Figure 10A), this indicates that after the fault rupture reached the surface, the loose and unbound sand weakened and absorbed the on-fault slip. The geophysical inversions of the Maduo earthquake have showed that there is 5-10 m of sub-surface coseismic slip [1,3]; these results differ from the field observations that indicate that the maximum surface rupture slip does not exceed 2 m. This phenomenon is generally considered to be caused by inelastic deformation near the surface [22,23]. According to the field investigation, the loose sand layer on the surface affects the exposure of rupture and the offset of the fault. Convergence of the India-Eurasia plates leads to the continued uplift of the Tibetan Plateau [24] and the eastward extrusion of Tibet along the large strike-slip faults. There are currently two end-member deformation models for the Tibetan Plateau that are the rigid block motion model [25, 26, 27] and the continuous deformation model [28, 29, 30, 31, 32]. Other proposed models are typically a combination of these two end-member models [33]. Based on the historical seismicity in this area (Figure 1), it is generally concluded that the large boundary faults accommodated most of the deformation of the plateau. However, there is still some stress that accumulates within the block. Because the Maduo earthquake is one of the rare earthquakes that occurred inside the Bayan Har Block, studying this earthquake provides valuable insight into the internal deformation mechanisms of Tibet. This research was funded by the National Natural Science Foundation of China (Grant No. 41872226).