大地震破裂过程反演中的灵活性需求:现状及探讨

Advances and perspectives of flexibile inversion for earthquake rupture processes

对于大地震破裂过程的反演是震源研究的重要问题,也是震源物理研究的基础.虽然大地测量、地震精定位等方法和数据的引进为大陆内部地震破裂过程的精细研究提供了重要依据,但对于大洋底部、俯冲带等区域的地震复杂破裂过程依然需要灵活度高的方法来获得多样的断层几何结构,并支持破裂过程反演.本文集中讨论震源研究中的一类灵活度高的方法:多点源模型反演.并结合震源反投影、有限断层模型等方法,分析这些方法在大地震破裂过程反演中的优势互补,提出反投影→多点源→有限断层模型串行的思路.通过上游方法的稳定性获得下游算法的先验约束,最终获得具有高灵活性、高时效性以及高精度的串行反演策略.

To determine the rupture processes of big earthquakes is a fundamental problem of earthquake studies,which also supports earthquake physics research.Although the joint use of seismic,geodetic and seismicity data provides good constraints to determine the fault plane information of inland earthquakes,it is still challenging to unveil non-planar fault planes for oceanic earthquake ruptures.For complicated earthquakes,that ruptured more than one fault plane,a method to stably obtain focal mechanism changes is required to determine the fault plane information precisely.In this study,we analyze the stability and flexibility of multiple seismic methods,i.e.back-projections,multi-point-source inversion and finite fault inversion,to determine the rupture kinematics of big earthquakes,and find the stability spatial-temporal resolution and flexibility to resolve focal mechanisms that are not compatible in each single techniques.A sequential strategy is thus proposed to use back-projection results to prescribe the a priori information of multi-point-source inversion to achieve mechanism changing point source solutions with high spatial-temporal accuracy.Two strategies to connect these two techniques and other technique concerns are also discussed.