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CAREER: Microfossils as Drivers for Submarine Landslides?

职业：微化石是海底滑坡的驱动因素吗？

基本信息

批准号：
1945011
负责人：
Julia Reece
金额：
$ 52.61万
依托单位：
Texas A&M University
依托单位国家：
美国
项目类别：
Continuing Grant
财政年份：
2020
资助国家：
美国
起止时间：
2020-06-01 至 2025-05-31
项目状态：
未结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1945011&HistoricalAwards=false
关键词：
CAREER Microfossils Drivers Submarine Landslides

项目摘要

Underwater landslides are natural hazards with potential societal and socioeconomic consequences. Landslides occur globally, can cause tsunamis, and pose threats to people and infrastructure, especially near coasts. To reduce this impact on people and infrastructure, it is critical to advance our understanding of slope stability in ocean sediments. This project focuses on continental margins where earthquakes typically do not occur, and as such, do not act as triggers for landslides. In these sites, it remains unclear how the skeletal remains of microorganisms that live in the ocean and end up in ocean sediments could potentially weaken and precondition those sediments for failure and underwater landslides. The goal of the education activities is to provide high impact learning experiences and research opportunities for high school, undergraduate, and graduate students. This project is geared towards students from underrepresented groups in a STEM field, namely geosciences, in Texas, which lacks Earth science curriculum requirements. This will be achieved through an annually recurring education program with the local Bryan High School consisting of classroom visits, a one-day workshop, and two-week summer research activity. An undergraduate and graduate student course will be developed, which includes a domestic field trip to West Texas and New Mexico to study submarine slope channels and landslide deposits. Through all components, this project will foster next-generation researchers who can facilitate interdisciplinary science and broad collaboration to advance knowledge and mitigate natural hazards.This research project integrates experimental and numerical efforts and aims to characterize the role of microfossils in generating weak layers, which could become large-scale glide planes for submarine landslides. In this project, marine sediments will be systematically mixed with diatomite in varying concentrations and under repeatable conditions. The research goals are to determine key microfossil concentrations with threshold behavior, exact location within the sediment package, and burial conditions under which overpressure may be induced and wide-spread failure initiated within or above a microfossil-rich weak layer. Therefore, this proposed research will not only provide insights into slope failure mechanisms for microfossil-rich sediments but will also help in identifying potential future glide planes from cores and/or logging data from submarine and lacustrine settings where landslides may occur without external triggers like earthquakes. To document mechanical, hydraulic, and shear properties of microfossil-rich marine sediments, uniaxial resedimentation and constant rate of strain consolidation, as well as direct shear and triaxial shear experiments will be conducted at effective stresses corresponding to common landslide initiation depths. Microstructural changes, microfossil deformation, and development of shear failure planes will be qualitatively and quantitatively characterized by integrating analysis of hydromechanical data from deformation experiments with microscale imaging observations. Numerical slope stability models will provide insights into upscaling measured properties and introducing heterogeneous layered systems that analyze the interaction between microfossil-rich weak layers with over-and underlying non-biogenic sediments.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.

水下滑坡是具有潜在社会和社会经济后果的自然灾害。山体滑坡在全球范围内发生，可能引发海啸，并对人员和基础设施构成威胁，特别是在沿海地区。为了减少对人类和基础设施的影响，提高我们对海洋沉积物中斜坡稳定性的认识至关重要。该项目的重点是大陆边缘，那里通常不会发生地震，因此不会引发山体滑坡。在这些地点，目前尚不清楚生活在海洋中并最终进入海洋沉积物的微生物的骨骼遗骸如何可能削弱这些沉积物并使其成为失败和水下滑坡的先决条件。教育活动的目标是为高中，本科和研究生提供高影响力的学习经验和研究机会。该项目面向来自德克萨斯州STEM领域（即地球科学）代表性不足的群体的学生，德克萨斯州缺乏地球科学课程要求。这将通过与当地布莱恩高中每年定期举办的教育计划来实现，该计划包括课堂参观，为期一天的研讨会和为期两周的夏季研究活动。将开发一个本科生和研究生课程，其中包括到西德克萨斯州和新墨西哥州进行国内实地考察，研究海底斜坡通道和滑坡沉积物。通过所有组成部分，该项目将培养下一代研究人员，他们可以促进跨学科科学和广泛的合作，以提高知识和减轻自然灾害。该研究项目将实验和数值研究结合起来，旨在描述微化石在产生软弱层中的作用，这些软弱层可能成为海底滑坡的大规模滑动面。在该项目中，海洋沉积物将在不同浓度和可重复的条件下系统地与水混合。研究目标是确定具有阈值行为的关键微体化石浓度、沉积物包内的确切位置以及可能诱发超压并在富含微体化石的软弱层内或上方引发大范围破坏的埋藏条件。因此，这项拟议的研究不仅将为富含微体化石的沉积物提供边坡破坏机制的见解，而且还将有助于从海底和湖泊环境的岩心和/或测井数据中识别潜在的未来滑动面，在这些环境中，滑坡可能会发生，而不会发生地震等外部触发因素。为了记录富含微体化石的海洋沉积物的机械、水力和剪切特性，将在对应于常见滑坡起始深度的有效应力下进行单轴再沉积和恒定应变固结速率以及直接剪切和三轴剪切实验。微构造变化，微体化石变形，剪切破坏面的发展将定性和定量的特点，从变形实验与微尺度成像观测的流体力学数据的综合分析。数值边坡稳定性模型将提供对放大测量属性的见解，并引入异质分层系统，分析富含微化石的软弱层与上方和下方非生物沉积物之间的相互作用。该奖项反映了NSF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。