Controls on ground surface deformation in thrust and reverse fault earthquakes

逆断层地震和逆断层地震对地表变形的控制

• 批准号: 2207119
• 负责人: John Shaw
• 金额: $ 23.81万
• 依托单位: Harvard University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-08-01 至 2025-07-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2207119&HistoricalAwards=false
• 关键词: Controls; ground; surface; deformation; thrust

Ground surface rupture during large earthquakes poses significant hazards to urban environments, critical information and energy transmission infrastructure, transportation systems, as well as other sensitive facilities in the United States and other parts of the world. This research will develop a robust physical understanding of the factors that control the style, distribution, and intensity of ground surface ruptures during thrust and reverse faults earthquakes. This will provide a basis for better forecasting the patterns of ground surface deformation during future earthquakes, with the goal of helping to reduce the loss of life and property. The research will also support the training of undergraduate and graduate students, and research results will be incorporated in new college classes, K-12 education programs, and public outreach through the Harvard Museum of Natural History.The study will employ the discrete element method (DEM) to generate a large suite of 2-dimensional models (~6,000) that will identify the role of various properties (e.g., fault dip, sediment strength, sediment thickness) in controlling the patterns of ground surface deformation. In addition, the study will develop 3-dimensional models that address inherent variability in surface deformation patterns along strike. The DEM method is well suited to this purpose as it effectively reproduces both the geologic processes of faulting and folding at depth, as well as the granular mechanics of soil and sediment deformation in the shallow subsurface. DEM enables the development of emergent features, such as fractures/fissures, secondary faults, flexural slip surfaces, and folds that comprise ground surface deformation patterns during large earthquakes. By systematically varying fault and sediment parameters in their models, the researchers will develop a mechanics-based understanding of controls on ground surface rupture patterns that can help to assess site-specific hazards. Through large suites of models, they will statistically assess the patterns of ground surface deformation to inform and enhance Probabilistic Fault Displacement Hazard Analysis (PFDHA) methods. PFDHA is established as the standard for hazard forecasting related to ground surface rupture, but is particularly challenged by thrust and reverse fault earthquakes due to the complexity of these ruptures and the paucity of historic events to use for calibration. Their results will provide a robust database to assess how slip at depth is manifest in both direct fault displacements and distributed ground surface deformation. This will help to calibrate PFDHA methods used in forecasting rupture locations, displacements, and other characteristics that pose risks to critical infrastructure.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.

大地震期间的地表破裂对美国和世界其他地区的城市环境、关键信息和能源传输基础设施、交通系统以及其他敏感设施造成重大危害。这项研究将对逆断层地震和逆断层地震期间控制地表破裂的类型、分布和强度的因素产生强有力的物理理解。这将为更好地预测未来地震期间地表变形模式提供基础，以帮助减少生命和财产损失。该研究还将支持本科生和研究生的培训，研究成果将纳入新的大学课程、K-12 教育计划以及通过哈佛自然历史博物馆进行的公共宣传。该研究将采用离散元方法（ DEM）生成大量二维模型（约 6,000 个），用于识别各种属性（例如断层倾角、沉积物强度、沉积物厚度）在控制地表变形模式中的作用。此外，该研究还将开发 3 维模型，以解决沿走向的表面变形模式的固有变化。 DEM 方法非常适合此目的，因为它有效地再现了深层断层和褶皱的地质过程，以及浅层地下土壤和沉积物变形的颗粒力学。 DEM 能够开发新兴特征，例如断裂/裂隙、次生断层、弯曲滑动面和褶皱，这些特征构成大地震期间的地表变形模式。通过系统地改变模型中的断层和沉积物参数，研究人员将对地表破裂模式的控制形成基于力学的理解，这有助于评估特定地点的危险。通过大量模型，他们将统计评估地表变形模式，为概率断层位移危险分析 (PFDHA) 方法提供信息和增强。 PFDHA 是作为与地表破裂相关的灾害预报标准而建立的，但由于逆断层地震和逆断层地震的复杂性以及用于校准的历史事件的缺乏，尤其受到逆断层地震的挑战。他们的结果将提供一个强大的数据库来评估深度滑动在直接断层位移和分布式地表变形中的表现。这将有助于校准用于预测破裂位置、位移和其他对关键基础设施构成风险的特征的 PFDHA 方法。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力优点和更广泛的影响审查标准进行评估，被认为值得支持。