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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受断层岩的物理性质控制：断层岩是在断层运动带内形成的物质。地震发生在地壳顶部10-20公里处（称为孕震区）。孕震区的断层岩（脆性断层岩）是由产生由许多小颗粒组成的物质的过程形成的，这些小颗粒相互滚动和滑动，流体在控制这些过程中发挥着重要作用。了解脆性断层岩的物理性质对于了解断层在数百万年时间尺度上的长期运动以及了解大地震的成核、破裂和停止都至关重要。新西兰的阿尔卑斯断层带是一个主要的板块边界断层，每200-400年产生一次大地震。断层运动包含了大量的右旋走滑成分-当一个人站在断层的一边时，另一边会向右移动（在数十万年的平均时间里，每年移动约35毫米）。它还涉及反向运动，因此东侧向上滑动并越过西侧，每年约10毫米。南岛西海岸的降雨量非常高，隆起的物质被迅速侵蚀，因此断层在数万至数百万年的时间里将物质从深处带到地球表面。10公里外的物质在100万年内到达地表。阿尔卑斯断层带的独特之处在于，地表的断层岩来自断层带的所有深度，而今天的活动断层正在产生等效的断层岩。我们可以在5公里深的地表上采集脆性断层岩的样本，我们可以使用地球物理学（遥感地球）来了解5公里深的活动断层中今天存在的条件，在那里产生了等效的断层岩。我们没有别的地方可以这样做。在这个建议中，我们的目标是收集第一个完整的部分脆性断层岩从阿尔卑斯山断层带，并使用这些更好地了解物理过程中的孕震区。脆性断层岩常被河流砾石覆盖，地表无完整剖面出露。因此，为了收集样本，我们计划钻透大约150米的岩石，并从钻孔中收集岩心。岩芯样本将在实验室进行分析，以便我们了解它们的物理特性，并能够更好地模拟它们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，并为国际大陆钻探计划支持的更雄心勃勃的深层钻探和相关科学计划提供垫脚石。最终目标是利用阿尔卑斯断层带作为天然实验室，了解孕震区岩石变形物理和地震破裂物理。