Quantifying the variability and migration of active normal faulting during the Late Pleistocene-Holocene using 36Cl cosmogenic nuclide techniques

使用 36Cl 宇宙成因核素技术量化晚更新世-全新世期间活动正断层的变化和迁移

• 批准号: NE/M019020/1
• 负责人: Laura Gregory
• 金额: $ 67.93万
• 依托单位: University of Leeds
• 依托单位国家: 英国
• 项目类别: Fellowship
• 财政年份: 2016
• 资助国家: 英国
• 起止时间: 2016 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FM019020%2F1
• 关键词: Quantifying; variability; migration; active; normal

Much of the Earth is prone to damaging earthquakes. Earthquakes cannot be predicted, and the variability of earthquake occurrence makes this natural hazard difficult to anticipate. There are many fault lines that have not had an earthquake during human history, and whilst these faults are indeed active and capable of having big seismic events, they are often not realised to be a threat. This is particularly true on the continents, where the strain that results from the collision of tectonic plates is distributed such that faults occur over huge areas and in complex networks, which may interact. The interaction of faults, and how they behave on prehistoric timescales, is poorly understood due to difficulties in measuring the past fault motion.During my fellowship, I will investigate the brittle faults that cause earthquakes on timescales longer than human history. During my fellowship, I will aim to measure how earthquake occurrence is variable over the last several tens of thousands of years. Some scientists have suggested that faults may have periods of intense earthquake activity, interspersed in quiet intervals, and I aim to quantify whether this occurs on faults in western Turkey. I will also produce models of this behaviour that will help to understand the fundamental variability of earthquakes.Each time a fault has a large earthquake, a portion of the ground along the fault line is moved relative to the ground next to it. On extensional faults, the fault plane is uplifted and preserved for many thousands of years. As the fault plane is uplifted, it is exposed to the cosmogenic radiation that is constantly bombarding the earth's surface. This high-energy radiation produces isotopes that are otherwise not found on Earth; the result is akin to sunburn of the fault plane. The longer the plane has been exposed to cosmogenic rays, the higher the concentration of isotopes (the darker the tan). I will measure profiles of cosmogenic isotope concentrations on exposed fault planes in order to determine the history of fault exposure due to earthquakes. My results will quantify how long periods of intense seismicity last, how frequently they occur, whether they occur on every fault in a network, and whether faults in the network switch on and off relative to one another. I will also incorporate my data into models of fault behaviour. Many models assume that earthquakes occur in regular intervals, but it is important to model what is driving irregular recurrence. The models will also help to understand the physical interaction between faults in complex networks.My research will have impact on understanding earthquake hazard both locally, in western Turkey, and worldwide. During my fellowship whilst conducting field work in Turkey, I will conduct a ShakeOut drill in local communities, in collaboration with Prof Hasan Sozbilir. This drill is already practised in earthquake prone regions across the globe, including in the USA and Japan (www.shakeout.org). By having a mock earthquake once per year, the drill helps to increase disaster preparedness by encouraging participants to go through an earthquake checklist that includes building an earthquake-ready kit with essential survival items, practicing how to take cover during an earthquake, and determining what to do after the event. The greater impact of my research will be realised by communication of my results with scientists and policy makers alike, and efforts to increase the uptake of new understanding of fundamental earthquake behaviour.

地球的大部分地区都容易发生破坏性地震。地震是无法预测的，地震发生的可变性使这种自然灾害难以预测。有许多断层线在人类历史上没有发生过地震，虽然这些断层确实是活跃的，能够发生大地震事件，但它们往往没有意识到是一种威胁。在大陆上尤其如此，那里由于构造板块碰撞而产生的应变分布，使得断层出现在巨大的区域和复杂的网络中，这些网络可能相互作用。断层的相互作用，以及它们在史前时间尺度上的行为，由于难以测量过去的断层运动而知之甚少。在我的研究期间，我将研究在比人类历史更长的时间尺度上引起地震的脆性断层。在我的研究期间，我将致力于测量地震发生在过去数万年中的变化。一些科学家认为，断层可能有强烈的地震活动期，穿插在平静的间隔，我的目标是量化这是否发生在土耳其西部的断层。我还将建立这种行为的模型，这将有助于理解地震的基本可变性。每次断层发生大地震时，断层线上的一部分地面沿着相对于旁边的地面移动。在伸展断层上，断层面被抬升并保存了数千年。当断层面被抬升时，它暴露在不断轰击地球表面的宇宙射线之下。这种高能辐射产生的同位素在地球上是找不到的;结果类似于断层面的晒伤。飞机暴露在宇宙射线下的时间越长，同位素的浓度就越高（棕褐色越深）。我将测量暴露断层面上宇宙成因同位素浓度的剖面，以确定地震导致的断层暴露历史。我的研究结果将量化强烈地震活动的持续时间，它们发生的频率，它们是否发生在网络中的每个故障上，以及网络中的故障是否相对于彼此打开和关闭。我还将把我的数据纳入故障行为模型。许多模型假设地震发生的时间间隔是有规律的，但重要的是要模拟是什么驱动了不规则的复发。这些模型也将有助于理解复杂网络中断层之间的物理相互作用。我的研究将对理解土耳其西部和全球的地震危险产生影响。在我的奖学金，而在土耳其进行实地工作期间，我将在当地社区进行ShakeOut演习，与教授哈桑Sozbilir合作。这种演习已经在包括美国和日本在内的地球仪地震多发地区进行（www.shakeout.org）。通过每年一次的模拟地震，演习有助于通过鼓励参与者通过地震检查表，包括建立一个地震准备工具包与基本的生存物品，练习如何在地震中采取掩护，并确定在事件发生后做什么来提高备灾能力。我的研究的更大影响将通过与科学家和政策制定者的交流来实现，并努力增加对基本地震行为的新理解。

项目成果

Vertical axis rotation (or lack thereof) of the eastern Mongolian Altay Mountains: Implications for far-field transpressional mountain building

• DOI: 10.1016/j.tecto.2018.03.020
• 发表时间: 2018-06
• 期刊: Tectonophysics
• 影响因子: 2.9
• 作者: L. Gregory;C. Mac Niocaill;R. Walker;G. Bayasgalan;T. Craig

Active faulting in western Turkey: the challenge of earthquake hazard estimation in a complex extensional regime based on cosmogenic isotope analyses

土耳其西部的活动断层：基于宇宙成因同位素分析的复杂伸展体系中地震危险性估计的挑战

• DOI: 10.5194/egusphere-egu2020-18658
• 发表时间: 2020
• 作者: Gregory L

Determining Histories of Slip on Normal Faults With Bedrock Scarps Using Cosmogenic Nuclide Exposure Data

• DOI: 10.1029/2020tc006457
• 发表时间: 2021-01
• 期刊: Tectonics
• 影响因子: 4.2
• 作者: H. Goodall;L. C. Gregory;L. Wedmore;K. J. W. McCaffrey;R. Amey;G. Roberts;Richard Shanks;R. Phillips;Andrew Hooper

Determining reliable histories of slip on normal faults with bedrock scarps using cosmogenic exposure data

使用宇宙成因暴露数据确定基岩陡坡正断层滑动的可靠历史

• DOI: 10.1002/essoar.10503783.1
• 发表时间: 2020
• 作者: Goodall H

Partitioned Off-Fault Deformation in the 2016 Norcia Earthquake Captured by Differential Terrestrial Laser Scanning

差分地面激光扫描捕获的 2016 年诺尔恰地震中的分区断层变形

• DOI: 10.1029/2018gl080858
• 发表时间: 2019
• 期刊: Geophysical Research Letters
• 影响因子: 5.2
• 作者: Wedmore L