Collaborative Research: Chain Transform Fault: Understanding the dynamic behavior of a slow-slipping oceanic transform system

合作研究：链变换断层：了解慢滑海洋变换系统的动态行为

• 批准号: 2318854
• 负责人: Daniel Lizarralde
• 金额: $ 79.94万
• 依托单位: Woods Hole Oceanographic Institution
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2024
• 资助国家: 美国
• 起止时间: 2024-02-01 至 2028-01-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2318854&HistoricalAwards=false
• 关键词: Collaborative; Research; Chain; Transform; Fault

A longstanding goal of Earth Science is to understand why some sections of faults slip in large earthquakes while other sections do not. Oceanic transform faults are ideal for studying fault slip due to their simple composition and predictable motion - yet the spectrum of behavior on these faults is poorly understood. This study will employ a range of techniques to study the Chain transform fault in the equatorial Atlantic, which is an ideal locality due to its variable seismicity and its bathymetric expression that is typical of many transform faults. This project will train early career scientists in interdisciplinary marine science through their participation in research cruises and their analyses of data and samples. A broader cross-section of students will be engaged through a multi-institution virtual course on marine geology and geophysics. Oceanic transform faults consist of sections that slip in large earthquakes separated by sections that are primarily aseismic. Oceanic transform faults also display a variety of structural features – valleys, transverse ridges, median ridges, flower structures, fault segmentation – whose origins are linked to stress, strain, and material properties. A two-cruise experiment will be used to probe these fault dynamics. The first cruise aboard the R/V Langseth will collect multi-channel seismic data and deploy 20 ocean bottom seismometers. A year later, a second cruise will recover seismometers, deploy the autonomous underwater vehicle Sentry for high-resolution geophysical surveys, and use dredging to sample the active fault zone. These datasets will connect surface observations of fault structure and composition to seismic constraints at depth. Goals include:• Substantially advancing current understanding of slow-slipping transform faults.• Surface-to-depth images of fault structures from seismic data and Sentry micro-bathymetry.• Identification of active fault strands and areas of active uplift based on linking microseismicity patterns and focal mechanisms to fault structures.• Deciphering how strain is accommodated on poorly coupled portions of the fault, and whether, and at which depth, those portions are characterized by swarms of microseismicity, as has been observed at faster slipping transform faults.• Determination of the dominant lithologies in the fault zone—including in uplifted structures—using samples, photo transects, and seismic velocity.• Elucidation of the role of fluids in modifying fault-slip behavior, based on sample analyses, chemical-sensor datasets, seismic-velocity variations, and microseismicity distribution.• Location of sites of magmatic activity within a slow spreading transform and evaluation of source variability, melting systematics, and storage depths from magma compositions.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.

地球科学的一个长期目标是了解为什么某些断层在大地震中滑落，而其他部分则没有。海洋变换断层是由于其简单组成和可预​​测的运动而导致断层滑动的理想选择 - 但这些断层行为的范围却鲜为人知。这项研究将采用一系列技术来研究赤道大西洋的链变换断层，这是一个理想的位置，因为其可变地震性及其测深表达，这是许多变换断层的典型特征。该项目将通过参与研究巡游及其数据和样本的分析来培训跨学科海洋科学的早期职业科学家。通过有关海洋地质和地球物理学的多机构虚拟课程，将参与更广泛的学生横截面。海洋变换断层由截面组成，这些断层在大地震中滑落，而大地震被截面的海洋变换断层隔开，还显示了各种结构特征 - 山谷，横向脊，中间脊，花结构，断层分割 - 其起源与压力，应变和材料特性有关。将使用两次裂缝实验来探测这些故障动力学。 R/V Langseth上的第一次巡航将收集多通道地震数据并部署20个海洋底部地震米。一年后，第二次巡航将恢复地震仪，部署自动驾驶水下车辆哨兵进行高分辨率地球物理调查，并利用投资对活动断层区进行采样。这些数据集将将故障结构和组成的表面观测与深度的地震约束联系起来。目标包括：•实质上提高了对缓慢滑动变换故障的当前理解。•来自地震数据和哨兵微型聚合物的故障结构的表面对深度图像。•确定主动故障链和主动升高区域的识别，基于将微震动模式和焦点机制连接起来的链接到缺陷结构的不良范围。部分的特征是微量抗震动的特征，如在更快的滑动变换断层时观察到的。•确定断层区域中的主要岩性（包括隆起的结构中）的主要岩性（包括样品，照片样本和地震速度）。•基于对模式的分析式分析的作用，是在修改中的作用。 •岩浆活动变化的位置和岩浆构成的源变异性，熔化系统和储存深度的评估。该奖项反映了NSF的法定任务，并已被认为是通过基金会的知识分子的智力和更广泛的影响来评估CRITERIA，这是值得通过评估，这奖项反映了NSF的法定任务。