Spatio-temporal variations of slip on active norma faults in central and southern mainland Greece

了解地震在空间和时间上是如何发生的一直是一个复杂的问题。地震预测中的两个关键问题是不可预测的地震复发时间和不可预测的地震规模。对这些问题缺乏了解导致了地震发生时的破坏性后果。这些问题可能仍然无法解决，但我们可以开始通过调查几个因素，如断层位置，几何形状，运动学，几千年的滑动率历史和断层阵列的应变率，来提高对地震危险性的认识。这些因素很重要，在评估地震危险性时应予以考虑，因为它们涉及以下方面。(a)断层几何学可能涉及与地震有关的破裂运动学。断层几何学和运动学的分析可能有助于描述断裂的类型，并可能解释地震如何迁移。(b)几千年的滑动率历史分析时间周期足够长，以确定断层上的多次地震，并确定模式;集群和平静。(c)断层阵列的应变率揭示了数千年时间尺度上的总地震或应变如何在各地区分布。希腊是研究这些因素的完美天然实验室，因为该国包含复杂的活动断层网络。希腊海沟俯冲带和北安纳托利亚走滑断层形式的大型构造的组合导致了早期裂陷过程，产生了几个不同方向的正断层阵列。这些正断层经常表现出地震活动的形式，这些地震被认为是地壳拉伸与破坏性地震（Ms ~ 6.0或更大）发生约十年一次。博士项目的总体目标是调查不同的空间尺度从单一故障到整个故障阵列，同时结合时间方面，以帮助揭示千年规模的地震集群和平静的重要性。这将通过评估上述因素进行;断层位置;几何学;运动学;几千年滑动率历史;和断层阵列的应变率。一般来说，该项目将包括分析一个历史地震序列的具体例子，并为多个断层阵列制作一套应变率图。(Part 1）首先，将对在历史地震序列中破裂的两个断层进行局部空间调查，以分析断层几何形状可能对控制破裂类型的作用。(Part 2）将以36 Cl宇宙成因核素导出的两个断层的断层滑动历史的形式进行伴随的时间研究，将比较这两个断层，以试图了解邻近断层在其滑动历史方面如何或是否相关。(Part 3）应变率填图是在整个断层序列尺度上进行的时空调查，目的是显示全新世地震活动的区域分布。全新世应变率也将与已发表的历史应变率进行比较，以显示地震危险性在不同时间尺度上的空间变化。研究断层的时间和空间活动性将对改进地震危险性分析和改进地震预报产生重要影响。希腊构造环境复杂，地震活动频繁，是研究断层活动的理想场所。希腊断层已被研究，但是，更广泛的现场数据，以帮助限制因素（断层位置，几何形状，运动学，多千年滑动率的历史和应变率的断层阵列）在希腊大陆中部，因此，提高认识的构造过程和地震危险性。

Understanding how earthquakes occur in space and time has been a complex problem. Two key problems in earthquake forecasting are unpredictable earthquake recurrence times and unpredictable size of earthquakes. The lack of understanding of these issues have resulted in destructive consequences when earthquakes do occur. The problems may remain unsolvable but we can start to improve the understanding of seismic hazard by investigating several factors, such as, fault location, geometry, kinematics, multi-millennia slip-rate histories and strain-rate of fault arrays. The factors are important and should be considered in assessing seismic hazard as they address the following. (a) Fault geometry may relate to rupture kinematics associated with earthquakes. Analysis of the fault geometry and kinematics may help describe the style of ruptures and potentially explain how earthquakes migrate. (b) multi-millennia slip-rate histories analyse time periods long enough to identify multiple earthquakes on faults and identify patterns; clustering and quiescence. (c) Strain-rates of fault arrays reveal how the total combined earthquakes or strain over the multi-millennia timescale is distributed across regions.Greece is a perfect natural laboratory for studying these factors as the country contains a complex network of active faults. The combination of large structures in the form of the Hellenic trench subduction zone and the North Anatolian strike-slip fault have resulted in early stage rifting processes which have produced several differently orientated normal fault arrays. These normal faults frequently show activity in the form of earthquakes which are felt as the crust stretches with destructive earthquakes (Ms ~ 6.0 or greater) occurring approximately once a decade.The overall aim of the PhD project is to investigate different spatial scales from single faults to entire fault arrays whilst incorporating temporal aspects to help reveal the importance of millennia-scale earthquake clustering and quiescence. This will be undertaken by assessing the factors mentioned above; fault location; geometry; kinematics; multi-millennia slip-rate histories; and strain-rate of fault arrays. Generally, the project will include analysis of a specific example of a historic earthquake sequence and the production of a suite of strain-rate maps for multiple fault arrays. (Part 1) Initially, a local spatial investigation of two faults, which have ruptured during a historic earthquake sequence, will be undertaken to analyse the role that fault geometry may have on controlling the rupture style. (Part 2) An accompanying temporal study will be undertaken in the form of 36Cl cosmogenic nuclide-derived fault slip histories of the two faults which will be compared in an attempt to understand how or if the proximal faults relate in terms of their slip histories. (Part 3) The strain-rate mapping will be a temporal and spatial investigation at the scales of entire fault arrays with the aim of displaying the regional distributions of Holocene earthquake activity. The Holocene strain-rates will also be compared to published historical strain-rates to show that seismic hazard varies spatially on different time scales.Studying the temporal and spatial activity of faults will have an important impact on improving seismic hazard analysis and refining earthquake forecasting. Greece is a suitable location for studying faulting due to the complex tectonic setting and frequent earthquake activity. Greek faults have been studied, however, more extensive field data are required in order to help constrain the factors (fault location, geometry, kinematics, multi-millenia slip-rate histories and strain-rate of fault arrays) in central mainland Greece and therefore, improve the understanding of tectonic processes and seismic hazard.