Compiled locations of subduction deformation front, downdip end of high coupling, shelf break, and coastline

Compilation of data used to support the article: "Co-location of the downdip end of seismic coupling and the continental shelf break" (Malatesta et al., 2020). Along subduction margins, the morphology of the near shore domain records the combined action of erosion from ocean waves and permanent tectonic deformation from the convergence of plates. We observe that at subduction margins around the globe, the edge of continental shelves tends to be located above the downdip end of seismic coupling on the megathrust. Coastlines lie farther landward at variable distances. This observation stems from a compilation of well-resolved coseismic and interseismic coupling datasets. The permanent interseismic uplift component of the total tectonic deformation can explain the localization of the shelf break. It contributes a short wave-length gradient in vertical deformation on top of the structural and isostatic deformation of the margin. This places a hinge line between seaward subsidence and landward uplift above the downdip end of high coupling. Landward of the hinge line, rocks are uplifted in the domain of wave-base erosion and a shelf is maintained by the competition of rock uplift and wave erosion. wave erosion then sets the coastline back from the tectonically meaningful shelf break. We combine a wave erosion model with an elastic deformation model to illustrate how the downdip end of high coupling pins the location of the shelf break. In areas where the shelf is wide, onshore geodetic constraints on seismic coupling is limited and could be advantageously complemented by considering the location of the shelf break. Subduction margin morphology integrates hundreds of seismic cycles and could inform seismic coupling stability through time.

本数据集汇编了用于支撑论文《地震耦合下倾端与大陆陆架坡折带（continental shelf break）的空间重合》（"Co-location of the downdip end of seismic coupling and the continental shelf break"，Malatesta 等，2020）的相关研究数据。在俯冲带边缘（subduction margins），近岸区域的地貌形态记录了海浪侵蚀与板块汇聚引发的持续构造变形的共同作用。我们在全球范围内的俯冲带边缘观测到，大陆陆架的边缘往往位于大型逆冲断层（megathrust）上地震耦合（seismic coupling）下倾端的上方，而海岸线则以不等距离向陆地方向后撤。这一观测结论基于一套经过高精度解析的同震（coseismic）与震间（interseismic）耦合数据集汇编而成。总构造变形中的持续震间抬升分量，可解释陆架坡折带的空间定位：该分量在俯冲带边缘的构造变形与均衡变形之上，叠加了垂直变形的短波长梯度，从而在高耦合区域的下倾端上方，形成了海域沉降与陆域抬升之间的枢纽线。在枢纽线向陆一侧的区域，岩石处于浪基面（wave-base）侵蚀范围内并发生抬升，陆架的维持则取决于岩石抬升与海浪侵蚀之间的动态竞争。随后，海浪侵蚀使得海岸线偏离了具有构造意义的陆架坡折带。我们结合海浪侵蚀模型与弹性变形模型（elastic deformation model），阐释了高耦合区域的下倾端如何约束陆架坡折带的位置。在陆架较宽的区域，针对地震耦合的陆上大地测量约束（geodetic constraints）较为有限，此时可通过考量陆架坡折带的位置来有效补充相关数据。俯冲带边缘的地貌形态整合了数百个地震周期的演化信息，可为地震耦合的长期稳定性提供时空参考依据。