CAREER: Does long-term topography preserve details of the seismic cycle? Seeing through, and exploiting, the diverse forcings influencing actively deforming landscapes.

职业：长期地形是否保留了地震周期的细节？

• 批准号: 2237437
• 负责人: Adam Forte
• 金额: $ 47.55万
• 依托单位: Louisiana State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-06-01 至 2028-05-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2237437&HistoricalAwards=false
• 关键词: CAREER; Does; long; term; topography

The shape of topography in tectonically active regions reflects a balance between the uplift of rocks from tectonic forces and the removal of rock and sediment by erosive forces, the latter of which are mediated by the local details of the climate and the types of rocks exposed. If the climatic and rock type details are constrained, then aspects of topography, like the shape of rivers, can serve as proxies for details of the tectonic forces and reveal, for example, the location and relative activity of faults. While providing critical insight into active tectonics, these approaches tend to idealize rock uplift along faults as a steady process. However, in reality rock uplift and the growth of topography usually occurs through more punctuated processes, specifically long periods of slow distributed deformation between earthquakes and then sudden and violent deformation during earthquakes, which combined over millennia, result in the integrated and idealized average rock uplift. The extent to which details of this “seismic cycle” are preserved in topography is unclear, but unlocking potential records stored in topography would be transformative as it could provide insight into specifics critical for hazard assessments, like average time between earthquakes and the relative extents of earthquake ruptures, through relatively quick, easy, and cheap analyses from globally available topography data. This project explores the preservation potential of aspects of the seismic cycle through a two-pronged approach. First, a large and comprehensive suite of simulations of landscapes developing through successive earthquake events and with varying climate and lithology details are being used to develop a set of fingerprints for relating landscape form to earthquake details. Secondly, these fingerprints are being applied to regions with independently established histories of fault and earthquake activity to vet and refine the results from the simulations. The broad goal of this research is providing a critical set of tools for better understanding earthquake hazards, both domestically and abroad in regions that lack comprehensive seismic hazard assessments and improve the safety and security of populations living in regions of potential hazard. In addition to the research goals of this project, a set of unique educational tools to provide resources for understanding the ways in which topography more generally reflects the shaping tectonic and climatic forces is being developed. The results of this effort include a LandscapeLibrary, a large set of landscape simulations developed under a wide array of controlled conditions, which will be made available to the public through an interactive web interface. Additionally, a series of educational exercises which use the LandscapeLibrary are being developed for a range of education levels from secondary to graduate level, providing a far-reaching educational resource that will contribute to development of the STEM workforce and promote general understanding of the critical context for the surface of the Earth.Fundamental details of the tectonic history of actively deforming regions are encoded in their fluvial topography, but interpreting these histories requires full consideration of the array of forcing mechanisms contributing to their form. For example, significant prior work focused on the influence of spatially or temporally variable precipitation, variations in lithologic resistance to erosion, or autogenic processes within catchments, amongst others in complicating, the interpretation of tectonics from topography and the extent to which these additional forcings can be factored out and a meaningful tectonic signal can still be reliably extracted from fluvial topography. The tectonic signals interpreted from this topography typically are first-order characteristics of fault systems, e.g., the location and relative activity of major structures, their subsurface geometries, or temporal changes in their average slip rates, but which largely treat the deformation on faults, and resulting patterns in rock uplift driving topographic development, simplistically as rigid block motion. However, fault motion typically occurs seismically and with significant spatial variability in surface deformation within a single seismic cycle, and indeed, likely between seismic cycles driven by interseismic creep on non-locked portions of fault and strain accumulation on locked portions of faults which is released coseismically. The extent to which the seismic cycle influences the development of topography is fundamentally unknown, but a general assumption is that it can be safely ignored, and that topography reflects average slip rates and associated rates of rock uplift. However, some work has questioned this assumption, specifically whether a signal of incomplete recovery of interseismic strain by earthquakes may leave a signal in topography. More broadly, it remains unclear whether topography can record any details of the seismic cycle, but it is hypothesized in this project that it may, specifically because of interactions between the seismic cycle and other forcing mechanisms, such as spatially and temporally variable precipitation. This project is testing this hypothesis with an integrated modeling study coupled with a large-scale topographic analysis effort. Specifically, the project seeks to 1) use coupled surface processes and deformation models that simulate interseismic and coseismic deformation to identify topographic signatures of the seismic cycle and 2) assess whether these signals are recognizable in natural landscapes with independent constraint on at least parts of their seismic cycles. The project will provide crucial insight into the connections between the long-term topography developed in active deforming regions and short-term earthquake processes, which is a long-standing goal within both the tectonics and earth surface processes communities. This project follows recent efforts that attempt to use the topographic characteristics of simulated landscapes to extract more quantitative information from topography directly, e.g., estimation of slip rate magnitudes, but promises to extend our view to details of the seismic cycle and fault behavior. These details of the seismic cycle are a fundamental input for seismic hazard analysis, which is of great societal relevance, but extracting this critical information is often challenging, laborious, and expensive. As such, being able to assess even broad information about the seismic cycle of a fault system from something as ubiquitous and globally accessible as topography would be incredibly beneficial - and is a potential outcome from the proposed work. This effort will occur in tandem with the development of a large body of precomputed synthetic landscapes developed under diverse forcing conditions to build the LandscapeLibrary and an interface for easy access and visualization of this library. This resource, and educational materials developed with it, are designed to help provide an easy visual representation of landscape evolution for a variety of classroom purposes. The LandscapeLibrary will provide an invaluable resource for other geoscientist educators around the world who wish to provide their students an intuitive view of the diverse forcing on landscape evolution. Finally, this project will support one PhD student and a postdoctoral researcher.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.

构造活动区的地形形状反映了构造力对岩石的抬升和侵蚀力对岩石和沉积物的侵蚀之间的平衡，后者是由当地的气候细节和暴露的岩石类型所调节的。如果气候和岩石类型的细节受到限制，那么地形的各个方面，如河流的形状，可以作为构造力细节的代理，并揭示，例如，断层的位置和相对活动。虽然这些方法提供了对活动构造的关键见解，但它们倾向于将沿断层的岩石隆起理想化为一个稳定的过程。然而，在现实中，岩石隆起和地形的生长通常是通过更间断的过程发生的，特别是在地震之间的长时间缓慢分布变形和地震期间的突然和剧烈变形，这些过程结合在一起，形成了完整和理想的平均岩石隆起。这种“地震周期”的细节在多大程度上保存在地形中尚不清楚，但解锁存储在地形中的潜在记录将是革命性的，因为它可以通过相对快速、简单和廉价的全球可用地形数据分析，为灾害评估提供关键的细节，如地震之间的平均时间和地震破裂的相对程度。该项目通过双管齐下的方法探索了地震周期各方面的保护潜力。首先，通过连续的地震事件和不同的气候和岩性细节，对景观的发展进行了大量全面的模拟，以建立一套将景观形式与地震细节联系起来的指纹图谱。其次，这些指纹被应用于具有独立建立的断层和地震活动历史的地区，以审查和完善模拟结果。本研究的广泛目标是为国内外缺乏全面地震灾害评估的地区提供一套重要的工具，以更好地了解地震灾害，并提高生活在潜在危险地区的人口的安全保障。除了该项目的研究目标之外，一套独特的教育工具正在开发中，为理解地形更普遍地反映塑造构造和气候力量的方式提供资源。这一努力的结果包括一个景观图书馆，这是一个在各种受控条件下开发的大型景观模拟集，将通过交互式网络界面向公众提供。此外，正在为从中学到研究生的一系列教育水平开发一系列使用景观图书馆的教育练习，提供影响深远的教育资源，有助于STEM劳动力的发展，并促进对地球表面关键环境的一般理解。活跃变形区域的构造历史的基本细节在它们的河流地形中被编码，但是解释这些历史需要充分考虑促成它们形成的一系列强迫机制。例如，重要的先前工作集中在空间或时间变化的降水的影响，岩性抗侵蚀能力的变化，或集水区内的自生过程，以及其他复杂的因素，从地形解释构造，以及这些额外的强迫可以在多大程度上被剔除，并且仍然可以从河流地形中可靠地提取有意义的构造信号。从这一地形中解释的构造信号通常是断层系统的一级特征，例如，主要构造的位置和相对活动，它们的地下几何形状，或它们的平均滑动速率的时间变化，但它们在很大程度上将断层上的变形以及导致岩石隆起的模式简单地视为刚性块体运动驱动地形发展。然而，断层运动通常发生在地震上，并且在单个地震旋回内地表变形具有显著的空间变异性，实际上，在由断层非锁定部分的地震间蠕变和断层锁定部分的应变积累驱动的地震旋回之间也可能发生。地震周期对地形发育的影响程度基本上是未知的，但一般的假设是可以安全地忽略它，地形反映了平均滑动率和相关的岩石隆升率。然而，一些工作对这一假设提出了质疑，特别是地震对震间应变不完全恢复的信号是否会在地形上留下信号。更广泛地说，尚不清楚地形是否可以记录地震周期的任何细节，但在这个项目中假设它可能，特别是因为地震周期和其他强迫机制之间的相互作用，如空间和时间变化的降水。该项目通过综合建模研究和大规模地形分析工作来验证这一假设。具体来说，该项目寻求1)使用耦合的地表过程和变形模型来模拟地震间和同震变形，以识别地震周期的地形特征；2)评估这些信号在至少部分地震周期具有独立约束的自然景观中是否可识别。该项目将为活跃变形区域的长期地形与短期地震过程之间的联系提供重要的见解，这是构造学和地表过程社区的长期目标。该项目遵循了最近的努力，试图利用模拟景观的地形特征直接从地形中提取更多定量信息，例如，估计滑动率的大小，但承诺将我们的视野扩展到地震周期和断层行为的细节。地震周期的这些细节是地震危害分析的基本输入，具有重要的社会意义，但提取这些关键信息通常具有挑战性、费力且昂贵。因此，能够从像地形这样无处不在和全球可获得的东西中评估断层系统的地震周期的广泛信息将是非常有益的——这是拟议工作的潜在成果。这一努力将与在不同强迫条件下开发的大量预先计算的合成景观的发展相结合，以建立景观图书馆和一个易于访问和可视化的界面。该资源以及据此开发的教育材料，旨在为各种课堂目的提供景观演变的简单视觉表现。景观图书馆将为世界各地的地球科学家和教育工作者提供宝贵的资源，他们希望为他们的学生提供一个直观的景观演变的各种力量的观点。最后，该项目将支持一名博士生和一名博士后。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。