CAREER: Impacts of Earthquake Shaking on Seafloor Sediment Stability and Landslide Hazards

海底滑坡移动的大量沉积物对沿海地区和海底基础设施，包括海底电缆构成危险。该项目将综合利用日本近海和太平洋西北部近海地震活跃区的实地观察沿着地球物理数据和沉积物岩心，以及模拟自然地震引起的震动的实验室实验，以更好地了解海底滑坡发生的原因。该项目使用国际海洋发现计划和美国地质调查局新获得的数据和遗留数据。将对每个现场的样品进行实验室实验，以了解地震震动、沉积物物理性质、沉积物强度和滑坡可能性之间的关系。教育和推广计划的一个关键要素是解决第一代大学生在STEM领域代表性不足的问题。该项目将为地球科学STEM领域的第一代大学生提供研究经验。教育和推广的第二个主要因素是与其他五所大学（密歇根州，宾夕法尼亚州立大学，内布拉斯加州，威斯康星州和华盛顿）合作的一个合作项目，以测量“fanquakes”，通过类比体育赛事期间体育场的震动，向数十万学生和公众提供地震科学方面的推广。该项目支持研究生的培训。该项目研究地震震动与最上层100米海底沉积物稳定性之间的关系，这是最有可能发生海底滑坡的关键区域。地震可能引发海底滑坡，大量沉积物对全球人口稠密的沿海地区和海底基础设施（包括传输99%全球互联网数据的海底电缆）构成社会经济危害。该项目的目标是了解地震震动、沉积速率和沉积物岩性对整体边坡稳定性的相对影响。假设是：1）在静水孔隙压力条件下，暴露于地震震动的海底沉积物产生的剪切强度比没有地震震动的海底沉积物产生的剪切强度更大; 2）沉积速率高到足以产生超压，这将抵消由于固结停止而产生的地震强度增益。这些假设将进行测试，结合使用从三个活跃的边缘网站的地球物理数据和核心，控制动态震动实验室实验，和数值模拟的现场观测。实地地点跨越两种主要类型的活动边缘（会聚型巨型逆冲俯冲带（卡斯卡迪亚和日本海沟）和走滑型（夏洛特女王断层边缘）），并依赖于国际海洋发现计划和美国地质调查局新获得的数据和遗留数据。将对每个现场的样品进行受控实验室实验，使用最先进的动态剪切实验，以澄清地震震动、沉积物物理性质和在一系列材料和震动强度范围内的剪切强度响应之间的关系。为了了解非均质边缘地层在多个维度上的更复杂行为，数值模型将量化深度限制（垂直有效应力），沉积物不再受到地震强化，以及地震强化如何在具有不同岩性，沉积速率，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。

The massive amount of sediment moved by seafloor landslides is a hazard to coastal areas and to seafloor infrastructure including undersea cables. This project will use a combination of field observations from seismically active regions offshore Japan and offshore the Pacific Northwest along with geophysical data and sediment cores, and laboratory experiments that simulate the shaking induced by natural earthquakes to obtain a better understanding of why submarine landslides occur. The project uses newly acquired and legacy data from the International Ocean Discovery Program and the United States Geological Survey. Laboratory experiments will be performed on samples from each field site to understand the relationships between earthquake shaking, sediment physical properties, strength of the sediment, and the potential for a landslide. A key element of the education and outreach plan is to address under-representation of first-generation college students in STEM fields. This project will provide research experiences to first-generation college students majoring in the STEM field of earth sciences. A second major element of the education and outreach is a collaborative project with five other universities (Michigan, Penn State, Nebraska, Wisconsin, and Washington) to measure ‘fanquakes’, to provide outreach to hundreds of thousands of students and the public on the science of earthquakes by analogy to stadium shaking during sporting events. The project supports the training of graduate students. This project examines the relationship between earthquake shaking and stability of the uppermost 100 meters of ocean seafloor sediments, which is the critical zone where submarine landslides are most likely to occur. Earthquakes can trigger submarine landslides, and the massive sediment mobilized is a socio-economic hazard to populated coastal areas worldwide and seafloor infrastructure including undersea cables that route 99% of global internet data. The project goal is to understand the relative influence of earthquake shaking, sedimentation rate, and sediment lithology on overall slope stability. The hypotheses are 1) in hydrostatic pore pressure conditions, seafloor sediments exposed to earthquake shaking develop an enhanced shear strength greater than would be achieved without earthquake shaking, and 2) sedimentation rates high enough to develop overpressure will offset seismic strength gains because of the arrested consolidation. These hypotheses will be tested using a combination of field observations from three active margins sites with geophysical data and cores, controlled dynamic shaking laboratory experiments, and numerical simulations. The field sites span two primary types of active margins (convergent megathrust subduction zones (Cascadia and Japan Trench) and strike-slip (Queen Charlotte Fault Margin), and rely on both newly acquired and legacy data from the International Ocean Discovery Program and the United States Geological Survey. Controlled laboratory experiments will be performed using state-of-the-art dynamic shear experiments on samples from each field site to clarify relationships between seismic shaking, sediment physical properties, and shear strength response over a range of materials and shaking intensities. To understand more complex behavior in multiple dimensions within heterogeneous margin stratigraphy, numerical models will quantify depth limits (vertical effective stress) where sediments are no longer subjected to seismic strengthening, and how seismic strengthening varies between different active margins with differing lithologies, sedimentation rates, and earthquake histories.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.