Rupture process of the 2021 M7.4 Maduo (Tibet) earthquake and its implication to the deformation mechanism of the Songpan-Ganzi Terrane

岳汉 助理教授

北京大学 理论与应用地球物理研究所

2022.03.04（星期五）15:00，理科二号楼2821

报告摘要：

The deformation mode of the Tibetan Plateau is of crucial importance for understanding its construction and extrusion processes, as well as for the assessment of the regional earthquake potential.  Block motion and viscous flow models have been proposed to describe the deformation field, which, however, are not fully supported by modern geophysical observations. The 2021 Mw 7.4 Maduo earthquake occurred inside the Songpan-Ganzi terrane (SGT) in central-east Tibet, which provides a new chance to evaluate the associated deformation mode of the region. We conduct a joint inversion for this earthquake and resolve a bi-lateral rupture process, which is characterized by super- and sub-shear rupture velocities, respectively. We interpret this distinct rupture behavior as the result of the respective slip concentration depths of the two ruptured segments. We analyze geological, seismic, and geodetic evidence, and find that the SGT upper crust shows distributed shear deformation and distinct transverse anisotropy, which are associated with folded structures originated from the compression of the paleo-Tethys ocean accretional prism and re-aligned by the followed shear deformation. The SGT receives lateral shear loading from sidewalls and accommodates a left-step sinistral motion across terrane boundary faults. The unique tectonic setting of the SGT defines locations and behaviors of internal faulting and earthquakes such as the 2021 Maduo earthquake, with the latter occurring on slow-moving faults at a couple of thousands of years interval.

报告人简介：

教育以及科研经历

2007          北京大学地球物理专业    学士

2010          北京大学地球物理专业    硕士

2014          加州大学圣克鲁兹分校    博士

2014-2017          加州理工大学           博士后

2017-今       北京大学地球物理专业    助理教授/特聘研究员

荣誉及人才计划

2021   中国地震协会李善帮青年科技成果奖（一等奖）

2016   国家级人才计划青年项目入选者

2014   加州理工大学地震实验室博士后奖学金

2013   教育部优秀自费留学生奖学金

学术任职

2021-今  JGR：Solid Earth 副主编