权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

Remote Triggering of Deep Earthquakes

远程触发深层地震

基本信息

批准号：
NE/X009807/1
负责人：
David Dobson
金额：
$ 10.25万
依托单位：
University College London
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2023
资助国家：
英国
起止时间：
2023 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=NE%2FX009807%2F1
关键词：
Remote Triggering Deep Earthquakes

项目摘要

Deep earthquakes are enigmatic because at very high pressures friction should stop rocks from rupturing. So we find in most of the Earth's mantle there are no earthquakes and rocks deform plastically. However in subducting slab regions there are significant numbers of really quite large earthquakes occurring down to almost 700 km depth - these are deep earthquakes. In order for seismicity at this depth we need a mechanism which will allow stresses to build up to a critical level and then produce very rapid strains, sufficiently fast for seismic waves to be produced and recorded at the Earth's surface. Laboratory experiments have shown that phase transformation from the main upper mantle mineral olivine to its high-pressure polymorphs can provide this kind of stress critical process, known as anticrack faulting. But anticrack faulting does not occur all the way down to 700 km depth and indeed the largest deep earthquakes do not occur in a region where metastable olivine persists.One possibility is that faults produced in the transforming region then cause stresses to increase in regions outside transformation and the rupture can slowly propagate from the anticrack faulting region into the surrounding slab. This model is known as remote triggering, and is popular among seismologists who study deep earthquakes, but it has yet to be proven demonstrated in experimental simulations of faulting processes. This study will investigate ways in which anticrack fulting can cause larger earthquakes away from the region of transformation. In studying this remote triggering process we will develop new tests for faulting mechanisms which will be applicable to both the deep Earth and also to monitoring man-made seismicity such as might occur during resource abstruction and carbon sequestration.

深源地震是神秘的，因为在非常高的压力下，摩擦力应该阻止岩石破裂。所以我们发现在大部分的地幔中没有地震，岩石是塑性变形的。然而，在俯冲板块区域，有相当数量的真正相当大的地震发生在近700公里的深度-这些都是深地震。为了使地震活动在这个深度，我们需要一个机制，将允许应力建立到一个临界水平，然后产生非常快速的应变，足够快的地震波产生和记录在地球表面。实验室实验表明，从主要的上地幔矿物橄榄石到其高压多晶型物的相变可以提供这种应力临界过程，称为反裂断层。但是，在700公里深处并不存在逆断层，而且最大的深震也不会发生在亚稳橄榄石存在的地区。一种可能性是，在转换区产生的断层导致转换区以外的应力增加，破裂可以从逆断层区缓慢地传播到周围的板块。这种模型被称为远程触发，在研究深源地震的地震学家中很受欢迎，但它还没有在断层过程的实验模拟中得到证实。这项研究将调查的方式，在反裂纹fulting可以导致更大的地震远离该地区的转换。在研究这种远程触发过程时，我们将开发新的断层机制测试，这些测试既适用于地球深处，也适用于监测资源破坏和碳封存期间可能发生的人为地震活动。