CAREER: Microfossils as Drivers for Submarine Landslides?

水下滑坡是具有潜在社会和社会经济后果的自然灾害。全球都会发生山体滑坡，可能引发海啸，并对人民和基础设施构成威胁，尤其是沿海地区。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理解至关重要。这个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，尚不清楚生活在海洋中并最终进入海洋沉积物的微生物骨骼遗骸如何可能削弱这些沉积物，并使这些沉积物成为破坏和水下滑坡的先决条件。教育活动的目标是为高中生、本科生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）代表性不足群体的学生，该领域缺乏地球科学课程要求。这将通过与当地布莱恩高中的年度经常性教育项目来实现，包括课堂参观、为期一天的研讨会和为期两周的暑期研究活动。将开设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合作，以推进知识和减轻自然灾害。本研究项目将实验与数值相结合，旨在表征微化石在形成弱层中的作用，这些弱层可能成为海底滑坡的大规模滑动面。在这个项目中，海洋沉积物将在不同浓度和可重复的条件下系统地与硅藻土混合。研究目标是确定具有阈值行为的关键微化石浓度，沉积物包内的确切位置，以及在富含微化石的弱层内或之上可能引起超压和广泛破坏的埋藏条件。因此，这项拟议的研究不仅将提供对富含微化石沉积物的斜坡破坏机制的见解，而且还将有助于从岩心和/或海底和湖泊环境的测井数据中确定潜在的未来滑动面，这些环境可能在没有地震等外部触发因素的情况下发生滑坡。为了记录富含微化石的海洋沉积物的力学、水力和剪切特性，将在与常见滑坡起裂深度相对应的有效应力下进行单轴再沉积和恒速率应变固结以及直接剪切和三轴剪切实验。微观结构变化、微化石变形和剪切破坏面的发展将通过整合变形实验和微尺度成像观测的流体力学数据分析来定性和定量地表征。数值斜坡稳定性模型将提供对升级测量属性的见解，并引入非均质层状系统，分析富含微化石的弱层与上下非生物沉积物之间的相互作用。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。

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.