In the southeastern Tibetan Plateau, the Xianshuihe-Xiaojiang fault system (XXFS) and its neighboring fault systems collectively accommodate the crustal extrusion of the Tibetan Plateau. However, we do not clearly understand how these faults interact with each other and how the fault interaction impacts fault slip rate, strain partitioning and crustal extrusion in this region. Through building a 3D viscoelastoplastic finite element model, we investigate the effects of fault geometry, fault configuration, lithospheric rheology and topographic loading on fault slip rate and crustal deformation. We find that the geometrical irregularity of Anninghe-Zemuhe faults in XXFS (a concave bend) prevents the crustal extrusion of the Chuandian (Sichuan-Yunnan) block, and tends to cause the inception of their subparallel Daliangshan fault on their east. On the other hand, the active Daliangshan fault decreases the slip rates on the Anninghe-Zemuhe faults, causing faster crustal extrusion of the Chuandian block. The active Lijiang-Xiaojinhe fault decreases the slip rates of faults in the south and hence hinders the crustal extrusion of the Chuandian block. Besides, the topographic loading plays an important role in the crustal extrusion of the southeastern Tibetan Plateau, by redistributing regional deformation and fault slip rates. Modeling results demonstrate that all faults in this region are kinematically connected and mechanically coupled: the slip rate change of one fault, both induce strain repartitioning and variations of slip rates on all other faults in such a system. Our research reveals the significant impact of fault interaction on fault activity and crustal extrusion in the southeastern Tibetan Plateau.

在青藏高原东南部，鲜水河-小江断裂系统（XXFS）及其邻近的断裂系统共同容纳了青藏高原的地壳挤压。然而，我们并不清楚这些断层之间如何相互作用以及断层相互作用如何影响该地区的断层滑动速率、应变分区和地壳挤压。通过建立 3D 粘弹塑性有限元模型，我们研究了断层几何形状、断层配置、岩石圈流变学和地形载荷对断层滑动速率和地壳变形的影响。我们发现XXFS（凹弯）安宁河-则木河断裂的几何不规则性阻碍了川店（四川-云南）地块的地壳挤压，并倾向于导致其东部平行的大凉山断裂的开始。另一方面，活动的大凉山断裂降低了安宁河-则木河断裂的滑动速率，导致川店地块的地壳挤压速度加快。活跃的丽江-小金河断裂降低了南部断裂的滑动速率，从而阻碍了川店地块的地壳挤压。此外，地形载荷通过重新分布区域变形和断层滑动速率，在青藏高原东南部的地壳挤压中起着重要作用。建模结果表明，该区域内的所有断层都是运动连接和机械耦合的：一个断层的滑移率变化，都会引起此类系统中所有其他断层的应变重新分配和滑移率变化。