Postdoctoral Fellowship: EAR-PF: Does topographic stress connect subsurface to surface through influencing bedrock strength, clast size, and landslides?

博士后奖学金：EAR-PF：地形应力是否通过影响基岩强度、碎屑尺寸和山体滑坡将地下与地表连接起来？

• 批准号: 2305448
• 负责人: Justin Higa
• 金额: $ 18万
• 依托单位: Higa, Justin T
• 依托单位国家: 美国
• 项目类别: Fellowship Award
• 财政年份: 2024
• 资助国家: 美国
• 起止时间: 2024-01-01 至 2025-12-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2305448&HistoricalAwards=false
• 关键词: Postdoctoral; Fellowship; EAR; PF; Does

Dr. Justin Higa has been awarded an NSF Earth Sciences Postdoctoral Fellowship to carry out research and professional development activities under the mentorship of Dr. Scott Rowland at the University of Hawaiʻi at Mānoa. Dr. Higa will examine the effects of topographic stress weathering in the valleys of Mt. Kahālāwai, Maui, Hawaiʻi, USA. Landslides from rocky, fractured mountains are deadly natural disasters that kill thousands of people every year. Research suggests that the shape of the land surface, the topography, can alter stresses within mountains to create some of these fractures and may help cause landslides. This process, called topographic stress weathering, is a budding frontier for understanding how fractures form in mountains. These fractures may weaken rock and generate fragments of rock that fall from steep slopes and collect in streams. Thus, there is a need to study whether topographic stress weathering is a major or minor contribution to the number and size of dangerous landslides on a mountain. Comparing calculations of topographic stress to rock strength, the size of rock fragments in streams, and mapped landslides may show how topographic stress weathering might affect landslide hazards. This project is important because it presents a new way to study natural disasters by linking topographic stress with field observations. Scientists can use such information to help protect people from landslides. Higa aims to engage with landowners and stakeholders of Mt. Kahālāwai to understand how this research can benefit local communities. Higa will also use this project to partner with Earth science students and help train a geologic workforce for the next generation of natural hazard scientists in Hawaiʻi.Recent studies on topographic stress weathering target how subsurface stress fields affect the extent and width of bedrock fractures. However, it remains unclear if topographic stresses are a major control of surface processes and natural hazards, such as landslides. This project will attempt to understand the relative contributions of topographic stress weathering versus climate in the generation of fractured rock and landslides. Previous work suggests that steep, narrow valleys concentrate fracture-inducing topographic stress perturbations at valley bottoms, whereas wider valleys may have such perturbations over larger areas. The study here will build off such work and focus on the valleys of an extinct volcano, Mt. Kahālāwai (also known as the West Maui Mountains), characterized by narrow and wide valleys with steep walls, a strong orographic rainfall gradient, and a lack of regional tectonic activity. First, a boundary element computer model will be used to predict the spatial distribution of topographic stresses within valleys of various morphologies (i.e., narrow or wide) and climates (i.e., windward or leeward). Next, researchers will collect (1) rebound hammer strength measurements of exposed bedrock, (2) size distributions of stream clasts, and (3) satellite mapping of landslides over decadal timescales from these valleys. If topographic stress controls surface processes, wide valleys may have weaker rocks, smaller clasts, and more landslides than steep, narrow valleys in similar climates. Then, comparing models and observations from valleys of similar morphologies but different climates will classify the effect of precipitation on weathering. Together, these tests will examine how topographic stress and climate work to erode steep valleys. Determining connections between topographic stress and geomorphic transport processes will help quantify the impact of stress-induced fracturing on various landscape evolution problems, which researchers can implement worldwide. Thus, this project may showcase a globally applicable method for examining weathering, erosion, and landslide hazards by establishing a framework linking topographic stress weathering and field observations.This project is jointly funded by the Division of Earth Science Postdoctoral Fellowship Program and the Established Program to Stimulate Competitive Research (EPSCoR).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.

Justin Higa 博士获得了美国国家科学基金会地球科学博士后奖学金，在夏威夷大学马诺阿分校 Scott Rowland 博士的指导下开展研究和专业发展活动。Higa 博士将研究地形应力风化的影响。美国夏威夷毛伊岛卡哈拉威山山谷 研究表明，岩石破碎山脉的山体滑坡是致命的自然灾害，每年都会造成数千人死亡。地表的形状（地形）可以改变山脉内部的应力，从而产生一些裂缝，并可能有助于引发山体滑坡，这一过程称为地形应力风化，是了解山脉裂缝如何形成的一个新兴前沿。削弱岩石并产生从陡坡落下并聚集在溪流中的岩石碎片，因此，有必要研究地形应力风化是对山上危险山体滑坡的数量和规模的主要还是次要贡献。地形应力对岩石强度的计算、溪流中岩石碎片的大小以及绘制的滑坡地图可以显示地形应力风化如何影响滑坡灾害，该项目很重要，因为它提供了一种通过将地形应力与现场联系起来研究自然灾害的新方法。科学家可以利用这些信息来帮助保护人们免受山体滑坡的影响。Higa 旨在与卡哈拉瓦伊山的土地所有者和利益相关者合作，了解这项研究如何使当地社区受益。该项目旨在与地球科学专业的学生合作，帮助夏威夷培养下一代自然灾害科学家的地质队伍。最近关于地形应力风化的研究目标是地下应力场如何影响基岩裂缝的程度和宽度。然而，目前尚不清楚。地形应力是地表过程和自然灾害（例如山体滑坡）的主要控制因素，该项目将尝试了解地形应力风化与气候在断裂岩石和山体滑坡生成中的相对贡献。山谷中导致断裂的地形应力扰动集中在谷底，而较宽的山谷可能在更大的区域内产生这种扰动，这项研究将在此类工作的基础上进行，并重点关注死火山卡哈拉瓦伊山（也称为西部）的山谷。茂宜山脉），其特点是山谷狭窄而宽阔，山壁陡峭，地形降雨梯度强，缺乏区域构造活动。首先，将使用边界元计算机模型来预测其空间分布。接下来，研究人员将收集（1）暴露基岩的回弹锤强度测量值，（2）溪流碎屑的尺寸分布，以及不同形态（即狭窄或宽阔）和气候（即迎风或背风）的山谷内的地形应力。 (3) 这些山谷在十年时间尺度上滑坡的卫星测绘如果地形应力控制地表过程，那么宽阔的山谷可能具有比这些山谷更脆弱的岩石、更小的碎屑和更多的滑坡。然后，比较具有相似形态但不同气候的山谷的模型和观测结果，对降水对风化的影响进行分类，这些测试将共同研究地形应力和气候如何侵蚀陡峭的山谷。地形应力和地貌迁移过程之间的关系将有助于量化应力引起的断裂对各种景观演化问题的影响，研究人员可以在全球范围内实施，因此，该项目可能会展示一种全球适用的检查风化、侵蚀和滑坡的方法。该项目由地球科学部博士后奖学金计划和刺激竞争研究既定计划（EPSCoR）共同资助。该奖项是 NSF 的法定使命，并被认为值得通过使用基金会的智力优势和更广泛的影响审查标准进行评估来提供支持。