The evolution of deformation mechanisms, physical conditions and physical properties in the seismogenic Alpine Fault zone: a pilot study

高山地震断裂带变形机制、物理条件和物理性质的演化：初步研究

基本信息

批准号：
NE/H012486/1
负责人：
Elisabetta Mariani
金额：
$ 10.31万
依托单位：
University of Liverpool
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2010
资助国家：
英国
起止时间：
2010 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=NE%2FH012486%2F1
关键词：
evolution deformation mechanisms physical conditions

项目摘要

The movement of large faults in the Earth's crust is controlled by the physical properties of the fault rocks: these are materials formed within the zone of fault movement. Earthquakes are generated in the top 10-20 km of the earth's crust (known as the seismogenic zone). The fault rocks in the seismogenic zone (brittle fault rocks) are formed by processes that produce material made up of lots of small particles that roll-around and slide past each other, with fluids playing an important role in controlling these processes. Understanding the physics of brittle fault rocks is crucial to understanding both the long-term movement of faults, on a time scale of millions of years, and to understanding the nucleation, rupture and cessation of large earthquakes. The Alpine Fault zone of New Zealand is a major plate-boundary fault that produces great earthquakes every 200-400 years. The fault movement involves a large component of dextral strike-slip - when one stands on one side of the fault the other side moves to the right (at about 35mm per year averaged over hundreds of thousands of years). It also involves reverse movement, so that the east side is sliding upwards and over the west side, at about 10 mm per year. There is a very-high rainfall on the west coast of the South Island and the uplifted material is eroded quickly so that the action of the fault over tens of thousands to millions of years is to bring materials from depth up to the Earth's surface. Materials from 10km get to the surface in a million years. What is unique about the Alpine Fault zone is that fault rocks at the surface have come from all depths in the fault zone and that equivalent fault rocks are being generated by the active fault today. We can sample brittle fault rocks at the surface that were formed at 5km depth and we can use geophysics (remote sensing into the Earth) to find out about what conditions exist today in the active fault at 5km depth, where equivalent fault rocks are being created. There is nowhere else where we can do this. In this proposal we aim to collect the first complete section of brittle fault rocks from the Alpine Fault zone and to use these to better understand the physics of processes in the seismogenic zone. The brittle fault rocks are often covered by river gravels and no complete section is exposed at the surface. So to collect the samples we plan to drill through about 150m of rock and collect cores from the drill hole. The core samples will be analysed in the laboratory so that we know their physical properties and can model better their behaviour on earthquake timescales and longer timescales. This project will involve significant international research collaboration and provides a stepping stone towards a more ambitious programme of deeper drilling and allied science supported by International Continental Drilling Programme. The ultimate goal is use the Alpine Fault Zone as a natural laboratory to understand the physics of rock deformation in the seismogenic zone and the physics of earthquake rupture.

地壳中大断层的运动由断层岩石的物理特性控制：这些是在断层运动区域内形成的材料。地震是在地壳的前10-20公里中产生的（被称为地震区）。地震区域中的断层岩石（脆性断层岩石）是由产生由许多小颗粒组成的过程形成的，这些材料由许多小颗粒组成，这些小颗粒互相滚动并彼此滑动，流体在控制这些过程中起着重要作用。了解脆性断层岩石的物理学对于在数百万年的时间范围内了解断层的长期运动以及理解大地震的成核，破裂和停止至关重要。新西兰的高山断层带是一个主要的板块边界断层，每200 - 400年一次会产生一次巨大的地震。断层运动涉及右旋滑动的很大一部分 - 当一个侧站立在断层的一侧时，另一侧向右移动（每年约35毫米，平均数十万年）。它也涉及反向运动，因此东侧每年约10毫米，向上和西侧滑行。南岛的西海岸有一个高的降雨量，而升起的材料迅速侵蚀，因此，超过数万到数百万年的断层的作用就是将材料从深度带到地球表面。 10公里的材料在一百万年内到达地面。高山断层区的独特之处在于，表面的断层岩石来自断层区域的所有深度，并且当今的活动故障正在生成等效的断层岩石。我们可以在5公里深度形成的表面上采样脆性断层岩石，我们可以使用地球物理（遥感到地球）来找出当今在5km深度的活动断层中存在哪些条件，在其中产生了等效的断层岩石。我们可以做到这一点。在此提案中，我们旨在从高山断层区收集脆性断层岩石的第一个完整部分，并利用这些岩石来更好地理解地震源性区域过程的物理。脆性断层岩石通常被河砾石覆盖，表面没有完整的部分。因此，要收集样品，我们计划钻探约150m的岩石，并从钻孔中收集岩心。核心样本将在实验室中进行分析，以便我们知道它们的物理特性，并可以更好地模拟其在地震时间尺度和更长时间尺度上的行为。该项目将涉及重要的国际研究合作，并为在国际大陆钻探计划支持的更深入的钻井和相关科学方面提供了更雄心勃勃的钻探计划。最终目标是将高山断层带作为天然实验室，以了解地震源区和地震破裂物理学中岩石变形物的物理。