Collaborative Research: Numerical modeling of fluid flow and transport during out of sequence thrusting and underplating: Application to the NanTroSEIZE investigation area

了解无序逆冲、流体排出、底侵和板块边界断层行为之间的相互作用对南开海槽地震孕育区实验(NantroseIZE)具有重要意义，但这些过程以前没有通过流体流动和变形模拟来检验。因此，这项模拟研究将解决这些主要过程对棱柱、巨型展布断层和板块边界断层内孔隙压力和流体流动的影响。建模将使用现有的软件包ABAQUS来实现。这个程序包提供了模拟对此模拟很重要的主要特征的能力，将允许其他研究人员重现模拟结果，并且足够灵活，以适应未来俯冲带模拟的需要。模型将应用于南开俯冲带的KII断面，并用于检验以下相关假设：假设1：巨型断裂系统显著改变了增长复合体内的超孔压和孔隙度损失的模式。假设2：通过观察孔隙压力、孔隙度、假设3：底侵作用通过将沉积物转移到不同的应力状态，并将滑脱带移动到较少脱水的区域，使增生棱柱底部的流体排出变得年轻。尽管这种模拟应用于南开俯冲杂岩的Kii断面，但对底侵作用和无序推覆作用对俯冲带降水和变形的重要性的评估将对其他俯冲带以及褶皱和冲断带的工作人员有用。展布断裂和底侵作用是许多俯冲带中可能极大改变孔隙压力和孔隙度分布(从而改变地震成因)的常见特征。广泛的影响了解孕震带过程具有与地震和海啸灾害相关的重大社会影响。这项研究将是地震孕育区长期调查的第一步。在调查过程早期进行的建模有助于在钻探和监测过程中形成科学的战略。ABAQUS软件包的使用将扩大俯冲带建模界的能力。模型输入数据集将提供给其他研究人员。作为NantroSEIZE的积极支持者，Liz Screaton将直接与其他支持者以及在未来的研讨会和NantroSEIZE相关会议上交流建模结果。此外，普遍感兴趣的结论将发表在科学期刊上，并在国家科学会议上发表。该项目将对研究生进行培养。在佛罗里达大学，它将适用于一名博士或两名硕士学生。在科罗拉多大学，项目工作将有一名学生(硕士或博士)参与建模。研究生将在科学会议上发言，该项目将是他们论文或论文的重要组成部分。

Understanding the interplay between out-of-sequence thrusts, fluid expulsion, underplating, and the behavior of the plate boundary fault is of fundamental importance to the Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE), but these processes have not previously been examined through fluid flow and deformation modeling. Accordingly, this modeling study will address the impact of these major processes on pore pressures and fluid flow within the prism, mega-splay fault, and plate boundary fault. The modeling will be implemented using an existing software package ABAQUS. This package offers the ability to simulate the major features important to this modeling, will allow modeling results to be reproducible by other researchers, and is flexible enough to accommodate needs of future subduction zone modeling.The model will be applied to the Kii transect of the Nankai subduction zone and used to test the following interrelated hypotheses:Hypothesis 1: The mega-splay fault system significantly alters the patterns of excess pore pressures and porosity loss within the accretionary complex.Hypothesis 2: The hydrologic role of the Nankai mega-splay system can be illuminated through observation of pore pressures, porosities, and fluid chemistry.Hypothesis 3: Underplating rejuvenates fluid expulsion at the base of the accretionary prism by transferring sediments to a different stress state and by moving the decollement zone to a less dewatered area.Although this application of the modeling is to the Kii transect of the Nankai subduction complex, an assessment of the importance of underplating and out-of-sequence thrusting for subduction zone dewatering and deformation will be useful for other subduction zones, as well as for workers in fold and thrust belts. Splay faulting and underplating are commonly inferred features that could greatly alter pore pressure and porosity distributions (and thus seismogenesis) in many subduction zones.Broader ImpactUnderstanding seismogenic zone processes has great societal impact related to earthquake and tsunami hazards. This study will constitute an initial step in the long-term investigation of the seismogenic zone. Modeling conducted early in the investigative process can help to shape scientific strategies during drilling and monitoring. The use of the ABAQUS software package will expand the ability of the subduction zone modeling community. Model input data sets will be made available to other researchers. As an active proponent in NanTroSEIZE, Liz Screaton will directly communicate modeling results to fellow proponents and at future workshops and NanTroSEIZE-related meetings. In addition, general interest conclusions will be published in scientific journals and presented at national scientific meetings. This project will result in the training of graduate students. At University of Florida, it will be adapted to either one PhD or two M.S. students. At University of Colorado, the project work will involve a student (either MS or PhD) in the modeling. The graduate students will present at scientific meetings and the project will be a significant component of their dissertation or thesis.