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.

构造活动区域的地形形状反映了构造力引起的岩石抬升与侵蚀力对岩石和沉积物的去除之间的平衡，后者是由当地气候细节和暴露的岩石类型调节的。如果气候和岩石类型细节受到限制，那么地形的各个方面（例如河流的形状）可以作为构造力细节的代理，并揭示例如地壳的位置和相对活动。在提供对活动构造的批判性见解的同时，这些方法倾向于将沿断层的岩石隆起理想化为一个稳定的过程，但实际上，岩石隆起和地形的生长通常是通过更间断的过程发生的，特别是在长期的缓慢分布变形过程中。地震和地震期间突然剧烈的变形，结合了数千年，导致了完整的、理想化的平均岩石隆起。这种“地震周期”的细节在地形中保留的程度尚不清楚。但解锁地形中存储的潜在记录将具有变革性，因为它可以通过相对快速、简单的方式对全球可用的廉价地形数据进行分析，从而深入了解对灾害评估至关重要的具体细节，例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地震周期各个方面的保存潜力，首先，使用一系列针对连续地震事件以及不同气候和岩性细节而发展的景观的综合模拟来开发一个项目。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区域，以审查和完善模拟结果。除了该项目的研究目标外，还提供了一系列工具，以更好地了解国内外缺乏全面地震灾害评估的地区的地震灾害，并提高生活在潜在灾害地区的居民的安全和保障。提供资源以帮助理解的工具地形更广泛地反映了正在开发的构造和气候力量。这项工作的成果包括景观图书馆，这是在各种受控条件下开发的大量景观模拟，将通过交互式网络向公众开放。此外，一系列使用 LandscapeLibrary 的教育练习正在开发中，适用于从中学到研究生的各种教育水平，提供了影响深远的教育资源，将有助于 STEM 劳动力的发展并促进对 STEM 的普遍理解。批判的活跃变形区域的构造历史的基本细节被编码在它们的河流地形中，但解释这些历史需要充分考虑促成其形成的一系列强迫机制，例如，重要的先前工作重点。空间或时间变化的降水、岩性抗侵蚀能力的变化或流域内的自生过程的影响，以及其他复杂化的因素，从地形对构造的解释以及这些额外的程度可以分解出强迫，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。从该地形解释的构造信号通常是断层系统的一阶特征，例如主要构造的位置和相对活动及其地下几何形状。 ，或平均滑移率的时间变化，但主要处理断层上的变形，以及由此产生的驱动地形发展的岩石隆起模式，简单地视为刚性块体运动。通常在地震上发生，并且在单个地震周期内表面变形具有显着的空间变化，并且实际上，可能在由断层非锁定部分上的震间蠕变驱动的地震周期和同震释放的断层锁定部分上的应变积累之间发生。地震周期对地形发展的影响基本上是未知的，但一般的假设是可以安全地忽略它，并且地形反映了平均滑移率和相关的岩石隆起率。质疑这一假设，特别是地震震间应变不完全恢复的信号是否会在地形中留下信号。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，但在该项目中重新发现它可能会发生。 ，特别是由于地震周期与其他强迫机制（例如空间和时间变化的降水）之间的相互作用，该项目正在通过综合建模研究和大规模地形分析工作来检验这一假设。 ) 使用耦合模拟震间和同震变形的地表过程和变形模型，以识别地震周期的地形特征；2）评估这些信号是否在自然景观中被识别，并且至少对其部分地震周期具有独立约束。活跃变形区域发展的长期地形与短期地震过程之间的联系，这是构造学和地球表面过程界的长期目标，该项目遵循最近的努力。尝试使用模拟景观的地形特征直接从地形中提取更多定量信息，例如估计滑移率幅度，但有望将我们的视野扩展到地震周期和断层行为的细节。地震灾害分析的基本输入，具有很大的社会相关性，但提取这些关键信息通常具有挑战性、费力且昂贵，因此，能够从以下方面评估有关断层系统地震周期的广泛信息。无处不在且全球可访问，因为地形将非常有益 - 并且是拟议工作的潜在成果，这项工作将与在不同强迫条件下开发的大量预先计算的合成景观一起开发，以构建景观库和界面。该资源以及由此开发的教育材料旨在帮助为各种课堂目的提供简单的景观演化可视化表示，为其他地球科学家提供宝贵的资源。最后，该项目将支持一名博士生和一名博士后研究员。该奖项反映了美国国家科学基金会的法定使命，并通过评估被认为值得支持。利用基金会的智力优势和更广泛的影响审查标准。