Deep crustal structure of the North Anatolian Fault Zone and the earthquake cycle

北安纳托利亚断裂带的深部地壳结构与地震周期

• 批准号: NE/I028017/1
• 负责人: Sebastian Rost
• 金额: $ 104.18万
• 依托单位: University of Leeds
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2011
• 资助国家: 英国
• 起止时间: 2011 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FI028017%2F1
• 关键词: Deep; crustal; structure; North; Anatolian

The Earth's surface is broken into numerous tectonic plates, which are continually moving. The movement of the plates relative to each other is the source for most earthquake activity on Earth, which is typically focussed into narrow fault zones where the plates collide, pull apart, or slide past each other. Within the fault zones the deformation in the upper 10-15 km of the Earth's crust is localised onto narrow fault planes. Earthquakes occur when the stresses on the fault planes caused by plate motions overcome frictional resistance, and these represent significant hazard for communities living in fault zones - in the first decade of the 21st century alone, earthquakes killed 700,000 people. In strike-slip fault zones, where plates slide past each other, earthquakes typically only break the upper crust. We know that the lower crust (deeper than 10-15 km) must be deforming continuously, because we can measure how the ground surface deforms between earthquakes. But because rock samples or other direct measurements cannot easily be obtained from these depths, we have a poor understanding of how the lower crust behaves and influences the loading of stresses in the upper crust to cause major earthquakes.We propose an inter-disciplinary project with the aim of understanding the earthquake loading cycle (how stresses build through plate motions and are released in earthquakes) along a major European fault, the North Anatolian Fault Zone (NAFZ) in Turkey. The NAFZ is a strike-slip fault comparable in length and slip rate to the San Andreas Fault in California. It crosses a densely populated region of northern Turkey and constitutes a major seismic hazard - over 1000 km of the fault ruptured during 12 large earthquakes in the 20th century. The western end of the NAFZ ruptured in two major earthquakes in 1999 at Izmit on 17 August and Düzce, 87 days later, killing more than 30,000 people. A seismic gap remains south of Istanbul, an urban centre of more than 10 million people, where there is ~60% chance of significant shaking within the next few decades (Parsons et al. 2000).We aim to measure the properties of the fault in the lower crust to set constraints on the earthquake loading cycle along the NAFZ. The project involves (i) a novel high-resolution seismic experiment aimed at resolving the fault zone structure at depth, (ii) geological analysis of an exhumed fault zone representative of the mid to lower crust under the fault, and (iii) analysis of satellite measurements of surface displacement. The results from these studies will be used to build computational models of the earthquake loading cycle. In this project we aim to explain how the movements of the tectonic plates interact with the fault zone and how this is affected by the lower crustal structure. This will ultimately contribute to better assessment of the seismic hazard associated with large fault zone. The resulting synthesis of the geophysical and geological data together with geodynamical modelling will guide future investigations for other major strike-slip fault zones.

地球表面被分成无数个不断移动的构造板块。板块之间的相对运动是地球上大多数地震活动的来源，地震活动通常集中在狭窄的断层带，在那里板块碰撞、拉开或相互滑动。在断裂带内，地壳上部10-15公里的变形被局限在狭窄的断裂面上。当板块运动引起的断层面上的应力超过摩擦阻力时，就会发生地震，这对生活在断层带的社区来说是一个重大的危险——仅在21世纪的头十年里，地震就造成了70万人死亡。在板块相互滑动的走滑断裂带，地震通常只破坏上层地壳。我们知道下地壳（深度超过10-15公里）一定在不断变形，因为我们可以测量地震之间地表是如何变形的。但是，由于岩石样本或其他直接测量不能轻易地从这些深度获得，我们对下地壳的行为和影响上地壳应力载荷导致大地震的理解很差。我们提出了一个跨学科项目，旨在了解沿欧洲主要断层，土耳其的北安那托利亚断层带（NAFZ）的地震加载周期（应力如何通过板块运动建立并在地震中释放）。NAFZ是一条走滑断层，其长度和滑动速度与加州的圣安德烈亚斯断层相当。它穿过土耳其北部人口稠密的地区，构成了一个主要的地震危险——在20世纪的12次大地震中，超过1000公里的断层破裂。1999年8月17日在伊兹米特和87天后在<s:1>兹埃奇发生的两次大地震中，NAFZ的西端破裂，造成3万多人死亡。伊斯坦布尔是一个拥有1000多万人口的城市中心，其南部仍然存在地震间隙，在未来几十年内有60%的机会发生重大震动（Parsons et al. 2000）。我们的目的是测量下地壳断层的性质，以限制沿南纬带的地震加载周期。该项目涉及(i)一项新的高分辨率地震实验，目的是在深度上解决断裂带结构，（ii）对断层下具有代表性的中下地壳出土断裂带进行地质分析，以及（iii）对地表位移的卫星测量进行分析。这些研究的结果将用于建立地震荷载循环的计算模型。在这个项目中，我们旨在解释构造板块的运动是如何与断裂带相互作用的，以及这是如何受到下地壳结构的影响的。这将最终有助于更好地评估与大断层带有关的地震危险性。由此产生的地球物理和地质数据综合以及地球动力学建模将指导未来对其他主要走滑断裂带的调查。

项目成果

Geodetic observations of postseismic creep in the decade after the 1999 Izmit earthquake, Turkey: Implications for a shallow slip deficit

• DOI: 10.1002/2015jb012737
• 发表时间: 2016-04-01
• 期刊: JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
• 影响因子: 3.9
• 作者: Hussain, Ekbal;Wright, Tim J.;Houseman, Gregory A.
• 通讯作者: Houseman, Gregory A.

Constant strain accumulation rate between major earthquakes on the North Anatolian Fault.

• DOI: 10.1038/s41467-018-03739-2
• 发表时间: 2018-04-11
• 期刊: Nature communications
• 影响因子: 16.6
• 作者: Hussain E;Wright TJ;Walters RJ;Bekaert DPS;Lloyd R;Hooper A
• 通讯作者: Hooper A

Interseismic strain accumulation across the central North Anatolian Fault from iteratively unwrapped InSAR measurements

• DOI: 10.1002/2016jb013108
• 发表时间: 2016-12-01
• 期刊: JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
• 影响因子: 3.9
• 作者: Hussain, Ekbal;Hooper, Andrew;Bekaert, David P. S.
• 通讯作者: Bekaert, David P. S.

Constraints from GPS measurements on the dynamics of deformation in Anatolia and the Aegean

• DOI: 10.1002/2016jb013382
• 发表时间: 2016-12-01
• 期刊: JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
• 影响因子: 3.9
• 作者: England, Philip;Houseman, Gregory;Nocquet, Jean-Mathieu
• 通讯作者: Nocquet, Jean-Mathieu

New constraints on micro-seismicity and stress state in the western part of the North Anatolian Fault Zone: Observations from a dense seismic array

• DOI: 10.1016/j.tecto.2015.06.022
• 发表时间: 2015-08
• 期刊: Tectonophysics
• 影响因子: 2.9
• 作者: S. Altuncu Poyraz;M. U. Teoman;N. Türkelli;M. Kahraman;D. Cambaz;A. K. Mutlu;S. Rost;G. Houseman;David Thompson;D. Cornwell;M. Utkucu;L. Gülen