The Upper Transition From Seismic To Aseismic Faulting on Subduction Megathrusts

俯冲巨型逆冲上从地震到抗震断层的上部过渡

• 批准号: 0648331
• 负责人: Chris Marone
• 金额: $ 39万
• 依托单位: Pennsylvania State Univ University Park
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-04-01 至 2011-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0648331&HistoricalAwards=false
• 关键词: Upper; Transition; Seismic; Aseismic; Faulting

Intellectual Merit: This research investigates the cause of the world's largest earthquakes, which occur along subduction plate boundaries. These "megathrust" earthquakes rupture sections of the plate boundary, but we still do not understand how the limits of these rupture patches are determined. Goals of the work are to identify reasons why some sections of subduction plate boundaries fail catastrophically in large earthquakes whereas other sections fail by aseismic creep. Identifying these processes is essential to understanding the seismic cycle and predicting the behavior of subduction zones on time scales relevant to tsunami generation and seismic hazard. The research tests two hypotheses for the up dip limit of the seismogenic zone using a complementary set of laboratory-based approaches that focus on (1) frictional properties, including the effect of lithification and consolidation state, clay mineralogy, effective stress, and drainage conditions on frictional constitutive properties; and (2) fluid transport properties between lithification and consolidation state, composition, permeability, and rheology. Samples from ocean drilling cores, exhumed faults, and synthetic fault gouge will be analyzed in carefully controlled laboratory experiments on natural and synthetic samples over P-T, fluid, mineralogical, cementation, and compaction conditions that span the stability transition. Experiments include friction measurements, consolidation tests, measurement of elastic properties and permeability to constrain elastic stiffness, and measurements of effective stress. Biaxial and frictional shear experiments will be carried out as will uniaxial deformation and flow through tests. Broader Impacts: This research has the potential for significant societal impact from an improved understanding of fault mechanics and earthquake physics including tsunami generation and seismic hazard assessment. The effort also complements the NSF IODP and MARGINS programs. The project will train two graduate students and four undergraduate students with the students also getting opportunities to present the results of their research at professional meetings.

智力价值：这项研究调查了沿俯冲板块边界发生的世界上最大地震的原因。这些“巨型逆冲断层”地震使板块边界部分破裂，但我们仍然不明白这些破裂斑块的界限是如何确定的。这项工作的目标是确定俯冲板块边界的某些部分在大地震中灾难性破坏而其他部分因地震蠕变而破坏的原因。识别这些过程对于了解地震周期和预测俯冲带在与海啸发生和地震灾害相关的时间尺度上的行为至关重要。 该研究使用一套互补的基于实验室的方法测试了关于发震带上倾角极限的两个假设，这些方法侧重于 (1) 摩擦特性，包括岩化和固结状态、粘土矿物学、有效应力和排水条件的影响关于摩擦本构特性； (2)岩化和固结状态之间的流体传输特性、成分、渗透率和流变学。 来自海洋钻探岩心、挖出的断层和合成断层泥的样品将在严格控制的实验室实验中对天然和合成样品在跨越稳定过渡的 P-T、流体、矿物学、胶结和压实条件进行分析。实验包括摩擦测量、固结测试、限制弹性刚度的弹性特性和渗透性测量以及有效应力测量。 将进行双轴和摩擦剪切实验以及单轴变形和流动测试。更广泛的影响：这项研究有可能通过提高对断层力学和地震物理学（包括海啸产生和地震灾害评估）的理解而产生重大社会影响。这项工作还补充了 NSF IODP 和 MARGINS 计划。该项目将培训两名研究生和四名本科生，学生还有机会在专业会议上展示他们的研究成果。