Seismicity, Structure and Dynamics of the Gorda Deformation Zone

戈尔达变形带的地震活动、结构和动力学

• 批准号: 1131767
• 负责人: John Nabelek
• 金额: $ 26.4万
• 依托单位: Oregon State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-01-15 至 2018-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1131767&HistoricalAwards=false
• 关键词: Seismicity; Structure; Dynamics; Gorda; Deformation

Plate Tectonics is the notion that the Earth?s surface is comprised of large plates that form at mid-ocean ridges and are consumed by the process of subduction, largely near the margins of ocean basins. The plate tectonic model explains many observable phenomena, including the distribution of great earthquakes and violent volcanic eruptions. A central assumption of plate tectonic theory is that the plates are rigid. This assumption applies to most of the Earth?s surface, but there are exceptions. One exceptional region is the Gorda Basin, which is located west of northern California and southern Oregon. There is compelling evidence that the seafloor in this region is actively deforming ? including the occurrence of numerous earthquakes ? but just how the seafloor is deforming and why has eluded unambiguous interpretation for several decades. This deployment of Ocean Bottom Seismographs (OBS) has the objective of yielding a more detailed picture of earthquake seismicity in the Gorda Basin, and thereby resolving the manor and cause of the deformation. There is added interest in this problem because the Gorda Basin is being actively subducted beneath the adjacent continent, where major ?megathrust? earthquakes are known to have occurred. How deformation of the Garda Basin affects the potential for large damaging earthquakes in this region is unknown, but of considerable societal interest. An added broader impact of this project is that the deployment of OBSs for this project will supplement the Cascadia Initiative, an amphibious deployment of OBSs offshore and seismic stations onshore. A principal aim of the Cascadia Initiative is to develop a better understanding of seismicity and of megathrust earthquake risk along the Cascadia margin, which extends from northern California to southern British Columbia.

板块构造学是指地球？南极洲的表面由形成于大洋中脊的大板块组成，这些板块在俯冲过程中被消耗掉，主要是在海洋盆地的边缘附近。板块构造模型解释了许多可观察到的现象，包括大地震和剧烈火山爆发的分布。板块构造理论的一个核心假设是板块是刚性的。这个假设适用于地球的大部分地区吗？这是表面现象，但也有例外。一个特殊的地区是戈尔达盆地，它位于北方加州和俄勒冈州南部的西部。有令人信服的证据表明，该地区的海底正在积极变形？包括多次地震的发生？但几十年来，海底是如何变形的，以及为什么变形，一直没有得到明确的解释。部署海底地震仪的目的是更详细地了解戈尔达盆地的地震活动，从而解决变形的范围和原因。人们对这个问题更感兴趣，因为戈尔达盆地正在积极地俯冲到邻近的大陆之下，主要在哪里？大推力？地震是已知的。加尔达盆地的变形如何影响该地区发生大破坏性地震的可能性尚不清楚，但具有相当大的社会利益。该项目的另一个更广泛的影响是，为该项目部署海洋生物系统将补充卡斯卡迪亚倡议，即海上海洋生物系统和陆上地震站的两栖部署。卡斯卡迪亚倡议的一个主要目的是更好地了解从北方加州延伸到不列颠哥伦比亚省南部的卡斯卡迪亚边缘的地震活动性和沿着的巨型逆冲断层地震风险。