NSFGEO-NERC: Latest Pleistocene-Holocene incremental slip record of the Kekerengu-Jordan fault system, northern South Island, New Zealand

大地震沿着走滑断层破裂的标准模型是，产生地震的滑动发生在单一表面上。2016年11月14日新西兰凯库拉7.8级地震动摇了这种关于断层滑动行为的思考。最初似乎是一个事件造成的滑动沿着一个单一的故障，原来是更复杂的滑动跳跃从一个故障到另一个网络的故障称为马尔伯勒故障系统。在该项目中，来自英国南加州大学和新西兰的研究团队将使用多种尖端方法重建马尔伯勒断层系统断层之一--凯克伦古-约旦断层系统的滑动和古地震历史，该断层系统在2016年的事件中经历了约12米的滑动。该项目中收集的数据将与系统中其他断层的数据结合使用，以更好地了解地震复发率，更重要的是，这些断层之间的时空联系，这在凯库拉地震之前显然还没有得到很好的理解。了解大地震对日益城市化的美国人口的威胁对于促进积极有效的措施以减少未来的生命和财产损失至关重要。然而，由于目前缺乏关于整个相互连接的地震断层系统如何在大的、潜在的破坏性地震中储存和释放地震能量的信息，对大地震在时间和空间上发生的预期的理解仍然受到严重限制。全面的数据集，如将从这个项目中产生的数据集，将揭示断层系统中的主要断层如何相互作用，以产生潜在的破坏性地震。反过来，这类观测将有助于更好地预测美国类似断层网的情况，特别是在地震多发的加州，但更普遍的是，对美国大部分地区的所有主要断层。该项目有可能通过以下方式造福社会或促进预期的社会成果：妇女充分参与STEM，通过外联活动提高公众对STEM的科学素养，通过更好地了解地震的基本过程改善社会中个人的福祉，这将提高模拟地震灾害的能力，通过研究生培训发展多样化的具有全球竞争力的STEM劳动力，主要目的是促进对区域断层网络集体行为的理解，特别是对地震集群和应变瞬变等紧急现象的重要性的理解，这些现象在目前对地震物理学的理解中可能无法预料，并且在目前的地震灾害评估策略中也没有考虑到。越来越多的证据表明，大地震的发生在单一的故障和故障系统是不是一个随机的过程，越来越多的时间和空间的地震集群的观察，增量断层滑动率的变化，在故障加载率的变化，以及潜在的协调上蜡和上蜡的滑动区域断层系统中的机械互补故障。尽管对这些现象的原因和普遍性的透彻理解对于断层力学、地震物理学和更准确地评估地震危险性具有基本的重要性，但对这些行为的重要性的评估一直受到严重的数据限制。特别是，有太少的全面的古地震和增量断层滑动速率数据集，以充分评估的集体行为的主要板块边界断层系统在时间和空间。这项研究的重点是太平洋-澳大利亚板块边界在新西兰南岛北方，以记录一个完整的最新更新世-全新世（15 ka-目前）的增量板块边界滑动记录，包括所有主要结构的系统。研究小组将在以前工作的基础上，为Kekerengu-Jordan断层系统开发可靠的记录，这是一个85公里长的斜向反向右旋断层系统，是板块边界陆上部分滑动最快的断层，速度为25-30毫米/年。Kekerengu-Jordan断层系统的滑动在2016年Mw=7.8的Kaikoura地震中产生了大部分的力矩释放。新的红外后IRSL 225发光测年协议将用于Kekerengu-Jordan断层系统的关键站点，以及新西兰政府收集的新的地震后高分辨率激光雷达数据的其他站点。这种新的发光测年技术提供了精确和可重复的测年的贫碳沉积物的典型研究领域的精度大致相当于放射性碳测年。将增量断层偏移和海沟观测与后IR IRSL 225测年和碳-14分析相结合，将产生详细的断层滑动速率和地震年龄，沿着断层系统跨越几十次地震中的单个断裂。结合来自陆上和海上断层的现有数据集，包括位于Kekerengu-Jordan断层系统下方的俯冲巨型逆冲断层，该研究将促进全面，晚更新世以来板块边界应变时空释放系统分析该奖项反映了NSF的法定使命，并通过使用基金会的知识产权进行评估，优点和更广泛的影响审查标准。

The standard model for rupture of large earthquakes along strike-slip faults is that the slip that generates the earthquake occurs on a single surface. The November 14, 2016 Kaikoura, New Zealand, magnitude 7.8 earthquake shook up this thinking about fault slip behavior. In what initially seemed to be an event resulting from slip along a single fault, turned out to be more complex with slip jumping from one fault to another within a network of faults called the Marlborough fault system. In this project, a research team from the University of Southern California, United Kingdom, and New Zealand will use a variety of cutting-edge methods to reconstruct the slip and paleo-earthquake history of one of the Marlborough fault system faults, the Kekerengu-Jordan fault system, which experienced about 12 meters of slip in the 2016 event. Data collected in this project would be used in conjunction with data from other faults in system to better understand earthquake recurrence rates and, more importantly, the temporal and spatial linkage between these faults, something that was clearly not well understood before the Kaikoura earthquake. Understanding the threat from major earthquakes to an increasingly urbanized American population is of critical importance for facilitating proactive and efficient measures to reduce future loss of life and property. Yet understanding of what to expect in terms of the occurrence of large earthquakes in time and space remains severely limited by the current lack of information about how entire systems of inter-connected earthquake faults store and release seismic energy in large, potentially damaging earthquakes. Comprehensive data sets, such as those that will result from this project will reveal how the major faults in a fault system interact with one another to generate potentially damaging earthquakes. These kinds of observations will, in turn, allow for better forecasting of what to expect from similar fault networks in the United States, particularly in earthquake-prone California, but more generally for all of the major faults that underlie large parts of the country. The project has potential to benefit society or advance desired societal outcomes through full participation of women in STEM, increased public scientific literacy with STEM through outreach activities, improved well-being of individuals in society by better understanding of fundamental processes underlying earthquakes that would improve the capability to model earthquake hazards, development of a diverse, globally competitive STEM workforce through graduate student training, and increased partnerships through international collaboration.The primary aim is to advance understanding of the collective behavior of regional fault networks, particularly the importance of emergent phenomena such as earthquake clusters and strain transients that may not be expected in the current understanding of earthquake physics and that are not accounted for in current seismic hazard assessment strategies. Mounting evidence suggests that the occurrence of large earthquakes on both single faults and fault systems is not a random process, with increasing observations of temporal and spatial earthquake clustering, changes in incremental fault slip rates, variations in fault loading rates, and potentially coordinated waxing and waning of slip on mechanically complementary faults in regional fault systems. Although a thorough understanding of both the causes and generality of such phenomena is of basic importance for fault mechanics, earthquake physics, and more accurate assessment of seismic hazard, evaluation of the importance of these behaviors has been severely data limited. In particular, there are too few comprehensive paleo-earthquake and incremental fault slip rate data sets to fully assess the collective behavior of major plate-boundary fault systems in time and space. This study focuses on the Pacific-Australia plate boundary in northern South Island New Zealand in order to document a complete latest-Pleistocene-Holocene (15 ka-present) record of incremental plate boundary slip encompassing all major structures in the system. The research team will build on previous work by developing robust records for the Kekerengu-Jordan fault system, an 85-km-long, oblique reverse-dextral fault system, which is the fastest-slipping fault in the onshore part of the plate boundary at 25-30 mm/year. Slip on the Kekerengu-Jordan fault system generated most of the moment release in the 2016 Mw=7.8 Kaikoura earthquake. The new post-IR IRSL225 luminescence dating protocol will be used at key sites on the Kekerengu-Jordan fault system, and at additional sites located with the new post-earthquake high-resolution lidar data collected by the New Zealand government. This new luminescence dating technique provides precise and reproducible dating of carbon-poor sediments typical of those in the study area with precision roughly equal to that of radiocarbon dating. Combining incremental fault offsets and trench observations with post-IR IRSL225 dating, and carbon-14 analysis will yield detailed fault slip rates and earthquake ages along the fault system spanning individual ruptures back though several dozen earthquakes. In conjunction with existing data sets from both the onshore and offshore faults, including the subduction megathrust that underlies the Kekerengu-Jordan fault system, the research will facilitate a comprehensive, system-level analysis of plate-boundary strain release through time and space during latest Pleistocene-Holocene time.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.