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Understanding the physical processes causing surface creep on faults.

了解导致断层表面蠕变的物理过程。

基本信息

批准号：
2278788
负责人：
金额：
--
依托单位：
University of Oxford
依托单位国家：
英国
项目类别：
Studentship
财政年份：
2019
资助国家：
英国
起止时间：
2019 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=studentship-2278788
关键词：
Understanding physical processes causing surface

项目摘要

Faults have been knownto slip aseismicallyor creep at the surface since the 1960s when creep was observed along the San Andreas Fault following the 1966 Parkfield Earthquake 1. The San Andreas Fault has since been observed to be creeping along a 150km long sectionbetween San Juan Bautista and Parkfield. Since the discovery of creep along this section of the San Andreas Fault, creepmeters and alignment arrays have been installed to monitor the creep2. Surface creep has been observed on many other fault systems around the world. Creephas been observed on other large strike-slipfaults such as the North Anatolian Fault near Ismetpasa, Turkey 3and the Philippine Fault on the Island of Leyte 4. Strike-slip faults are not the only type of faults that have surface creep, with creep observed on reverse faults in Taiwan 5,6.Creep on faults has been observed to occur in bursts known as creep events; these can be identified on the recordings oncreepmeters(Figure 1).Creep events have variations in slip characteristics (slip rate, duration,and slip) as a result ofphysical processesthat causes creep events. Despite the observation of surface creep since the 1960s,thephysical processby which creep is produced is not yet known. Many models have been proposed for creep including,viscous rheology 7, rate-and state-friction 8, size-limited friction 9and shear-induced dilatancy 10. Each modelhas its own merits.However,the debate over which one process produces surface creep is still ongoing. Another fundamental question still tobeanswered is howmuch of the fault is involved in creep events are.Given creep eventsare recorded at point locations using creepmeters, we do not know how much of the fault is creeping during these events.By using complementary creepmeters, creep propagation along the Calaveras Faulthas been observed 11. By investigating creep propagation, thesize extent of these creep events maybe uncovered leading to a new understanding of the role surface creep plays in the wider earthquake cycle. AimsDetermine how big creep eventsare.Discriminate between physical models proposed for creep events.Implementand developa time-lapse imaging-based technique for monitoring surface creep.

自20世纪60年代以来，人们就知道断层会在地表滑动或蠕动，当时人们在1966年帕克菲尔德地震后沿着圣安德烈亚斯断层观察到蠕动。从那时起，人们就观察到圣安德烈亚斯断层正在沿着圣胡安鲍蒂斯塔和帕克菲尔德之间150公里长的路段蠕动。自从发现圣安德烈亚斯断层的这一段沿着有蠕变以来，已安装了蠕变仪和校准阵列来监测蠕变2。在世界各地的许多其他断层系统上都观察到了地表蠕动。在其他大型走滑断层上也观察到蠕动现象，如土耳其伊斯梅帕萨附近的北安纳托利亚断层3和莱特岛上的菲律宾断层4。走滑断层并不是唯一具有表面蠕动的断层类型，在台湾逆断层上也观察到了蠕动5，6.断层上的蠕动被观察到以称为蠕动事件的突发形式发生;这些可以在蠕动仪的记录上识别（图1）。蠕动事件具有不同的滑动特性（滑动速率、持续时间和滑动），这是导致蠕动事件的物理过程的结果。尽管自20世纪60年代以来就观察到了表面蠕变，但产生蠕变的物理过程尚不清楚。已经提出了许多蠕变模型，包括粘性流变学7，速率和状态摩擦8，尺寸限制摩擦9和剪切诱导的剪切力10。每一种模型都有其优点，但究竟是哪一种过程导致了表面蠕变，至今仍存在争论。另一个尚待回答的基本问题是蠕变事件涉及到断层的多少.由于蠕变事件是用蠕变仪在点位置记录的，我们不知道在这些事件期间有多少断层在蠕变.通过使用补充蠕变仪，已经观察到沿沿着卡拉维拉斯断层的蠕变传播11.通过研究蠕变传播，这些蠕变事件的大小范围可能会被揭示出来，从而对地表蠕变在更广泛的地震周期中所起的作用有了新的认识。目的确定蠕变事件有多大，区分为蠕变事件提出的物理模型，实施并开发一种基于时间推移成像的技术来监测表面蠕变。