Imaging faults at depth: the seismic transport properties of fault zones

深度断层成像：断层带的地震传输特性

• 批准号: NE/F019475/1
• 负责人: Ernest Rutter
• 金额: $ 14.22万
• 依托单位: University of Manchester
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2009
• 资助国家: 英国
• 起止时间: 2009 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FF019475%2F1
• 关键词: Imaging; faults; depth; seismic; transport

Earthquakes and fault slip are still relatively poorly understood phenomena. One of the principal reasons for this is that fault zones, at the crustal levels where earthquakes nucleate, are very difficult to observe. Field mapping of large faults at the surface can provide valuable information, but they are often incompletely exposed and/or have suffered continued slip and hence overprinting during exhumation. As a consequence seismology is one of the key tools used to investigate fault zone structure and properties at depth. It has the potential to show fault zone structure and dimensions, slip distributions, fracture damage, stress orientations and fault fluid pressures. However the seismic data have to be inverted to decipher fault zone structure and properties and these inversions often yield non-unique answers. In this research we aim to combine field mapping, laboratory measurements and seismic experiments on an exceptionally well-exposed and characterized fault zone in southern Spain in order to understand the sensitivity of the seismic signals to the observed surface structure and physical properties of the fault rocks as determined from detailed mapping and laboratory seismic measurements. As part of a tied studentship, we will also measure the seismic properties of rocks recovered from 3km depth on the San Andreas fault in California as part of the San Andreas Fault Observatory at Depth (SAFOD) project that recently drilled a scientific borehole through the fault near Parkfield. Natural seismicity recorded on borehole instruments will provide comparison with laboratory measurements and allow us to broaden the scope of the work by detailed analysis of another major fault zone. The combination of all these data will provide a greatly improved understanding of the controls on fault zone seismology leading to a clearer picture of fault zones at depth. Specifically, we will map in detail part of the Carboneras fault in southeastern Spain; a major strike-slip fault with 40km offset that has been exhumed from 4 to 6km depth. Samples from the fault zone will have their seismic properties measured in the laboratory, including the P and S wave velocity, the attenuation of the seismic waves, and the degree of the polarization the S waves. The field and laboratory data will be combined to create a synthetic 3D model of the fault zone in which earthquake events may be 'created' and the resultant seismic signals predicted. We will additionally conduct 'active' seismic experiments on the fault zone where controlled seismic sources from explosions will excite seismic waves that we can then measure with a carefully positioned seismic network within and around the fault zone. The signals from these experiments will help characterize the subsurface structure of the fault and can be compared with predicted signals from the detailed mapping and laboratory measurement program. The project will provide information on fault zone structure from direct observation of a major fault, measurements of the physical properties of a range of fault zone materials and direct seismic measurements of the fault zone that can be directly compared with the surface structure. These data will not only provide key insights in understanding fault zone structure and properties from seismic data, but they will also be of significant interest to the hydrocarbon and mining industries, as faults control the movement of subsurface fluids, leading to problems in the recovery of oil and gas, and also distribution of hydrothermally /transported, fault hosted ore deposits.

地震和断层滑动仍然是相对知之甚少的现象。其中一个主要的原因是，在地壳层面上，地震成核的断层带非常难以观察。对地表大断层的实地测绘可以提供有价值的信息，但它们往往暴露不完全和/或遭受持续滑动，因此在挖掘过程中出现叠印。因此，地震学是研究断裂带结构和深部性质的关键工具之一。它有可能显示断层带结构和尺寸，滑动分布，断裂损伤，应力方向和断层流体压力。然而，地震数据必须反演以破译断层带结构和性质，并且这些反演通常产生非唯一的答案。在这项研究中，我们的目标是结合联合收割机现场测绘，实验室测量和地震实验异常暴露和特征的断层带在西班牙南部，以了解地震信号的灵敏度，所观察到的表面结构和物理性质的断层岩确定从详细的测绘和实验室地震测量。作为一个捆绑的学生奖学金的一部分，我们还将测量从3公里深的圣安德烈亚斯断层在加州恢复岩石的地震特性作为圣安德烈亚斯断层观测深度（SAFOD）项目的一部分，最近通过帕克菲尔德附近的断层钻了一个科学钻孔。钻孔仪器记录的天然地震活动将提供与实验室测量的比较，并使我们能够通过对另一个主要断层带的详细分析来扩大工作范围。所有这些数据的结合将提供一个大大提高了对断层带地震学的控制，从而导致更清晰的断层带在深度的图片的理解。具体来说，我们将详细绘制西班牙东南部Carboneras断层的一部分;这是一个主要的走滑断层，偏移量为40公里，已从4至6公里的深度挖掘出来。将在实验室中测量断层带样品的地震特性，包括P波和S波速度、地震波衰减和S波偏振度。现场和实验室数据将被结合起来，以创建一个合成的断层带的三维模型，在该模型中，地震事件可能会被“创建”，并预测由此产生的地震信号。我们还将在断层带上进行“主动”地震实验，在那里，爆炸产生的受控震源将激发地震波，然后我们可以在断层带内和周围仔细定位地震网络进行测量。来自这些实验的信号将有助于表征断层的地下结构，并且可以与来自详细测绘和实验室测量程序的预测信号进行比较。该项目将通过直接观察一个主要断层、测量一系列断层带物质的物理性质以及对断层带进行可直接与地表结构进行比较的直接地震测量，提供有关断层带结构的信息。这些数据不仅将为从地震数据中了解断层带结构和性质提供关键见解，而且还将对油气和采矿业产生重大影响，因为断层控制地下流体的运动，导致石油和天然气的回收问题，以及热液/运输断层托管矿床的分布问题。

项目成果

Constraints on the movement history of the Carboneras Fault Zone (SE Spain) from stratigraphy and 40 Ar- 39 Ar dating of Neogene volcanic rocks

新近纪火山岩地层学和 40 Ar- 39 Ar 测年对卡沃内拉斯断裂带（西班牙东南部）运动历史的制约

• DOI: 10.1144/sp394.5
• 发表时间: 2013
• 期刊: Geological Society, London, Special Publications
• 作者: Rutter E

Seismic velocity modelling of the Carboneras Fault Zone, SE Spain

西班牙东南部卡沃内拉斯断层带的地震速度模拟

• DOI: 10.1016/j.tecto.2015.01.001
• 发表时间: 2015
• 期刊: Tectonophysics
• 影响因子: 2.9
• 作者: Taylor R

On the structure and evolution of the Sorbas basin, S.E. Spain

关于索尔巴斯盆地的结构和演化，S.E.

• DOI: 10.1016/j.tecto.2019.228230
• 发表时间: 2019
• 期刊: Tectonophysics
• 影响因子: 2.9
• 作者: Valetti L