Collaborative Research: Strain accumulation and release at the Kuril subduction zone from postseismic observations on the Kuril GPS Array in 2007-2014

合作研究：2007-2014年千岛GPS阵列震后观测中千岛俯冲带的应变积累和释放

• 批准号: 1141792
• 负责人: Mikhail Kogan
• 金额: $ 34万
• 依托单位: Columbia University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-06-01 至 2016-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1141792&HistoricalAwards=false
• 关键词: Collaborative; Research; Strain; accumulation; release

The 1,200-km-long Kuril megathrust in the northwest Pacific Ocean is one of the most seismically active regions on the Earth. It was the last major subduction zone totally unexplored by methods of space geodesy. In 2006?2007, a doublet of great earthquakes in this region partly ruptured one of the most conspicuous gaps in subduction-zone seismic activity (the 15 November 2006 Mw 8.3 thrust event and the 13 January 2007 Mw 8.1 extensional event). A large 15 January 2009 Mw 7.4 thrust earthquake in the same region demonstrated the heightened seismic hazard. The Kuril GPS Array was installed several months before the 2006?2007 earthquakes in collaboration between US and Russian scientists. Observations on the array documented coseismic and postseismic surface deformation following the great Kuril earthquakes. The immediate focus of this final phase of the project is on acquiring irreplaceable, transient postseismic data spanning the time period 2007?2014. This project will continue collaboration between US universities and institutions of the Russian Academy of Sciences.The data from the Kuril GPS Array collected in 2006?2011 allowed us to develop models of coseismic slip and models of postseismic mechanisms. It was shown that most of the postseismic motion was caused by the viscoelastic relaxation of shear stresses in the weak Maxwell viscosity asthenosphere. From experience with other postseismic studies, longer time series will allow us to develop more robust models of postseismic deformation and models of interseismic frictional coupling on the subduction interface. The complete 8-year-long data set is required to address fundamental problems: How much of the strain built up from subduction of the Pacific plate beneath the North American plate (the Sea of Okhotsk) has been released in the 2006 and 2007 Kuril earthquakes coseismically and postseismically? Is it possible to explain postseismic surface deformation at the Kuril subduction zone with the linear viscous mantle or a stress-dependent rheology is required? These problems are especially important after the giant 2011 Mw 9.0 Tohoku earthquake, which made the scientists question the validity of conventional precursors of large earthquakes: location of seismic gaps and location of asperities (patches of high frictional locking at a subduction interface).

西北太平洋的1,200公里长的Kuril Megathrust是地球上最活跃的地区之一。这是最后一个主要的俯冲带，完全没有被太空测量方法所探索的。在2006年？2007年，该地区的一场大地震局部发生了部分破裂，这是俯冲区域地震活动中最明显的差距之一（2006年11月15日MW 8.3 8.3推力事件和2007年1月13日MW 8.1扩展事件）。 2009年1月15日的大型MW 7.4在同一地区推动地震表明地震危险增加。 Kuril GPS阵列是在2006年2006年2007年与俄罗斯科学家之间合作的几个月之前安装的。对阵列的观察记录了大库里尔地震后的coseis震和后表面变形。该项目的最后阶段的直接重点是获取不可替代的，短暂的后震后数据，该数据涵盖2007年时间段？2014年。该项目将继续在美国大学和俄罗斯科学院的机构之间进行合作。2006年收集的Kuril GPS阵列的数据2011年，我们能够开发出Coseismisic Slip的模型和后观察机制的模型。结果表明，大多数的后震动运动是由弱麦克斯韦粘度软化量中的剪切应力的粘弹性松弛引起的。从其他地震后研究的经验，更长的时间序列将使我们能够开发出更强大的后视性变形模型和俯冲界面上的间歇性摩擦耦合模型。需要完整的8年数据集来解决基本问题：从北美板块下方的太平洋板块（Okhotsk海）下方的俯冲造成的菌株已于2006年和2007年释放，在2006年和2007年的Kuril地震上，在地球上和之后？是否可以使用线性粘性地幔或需要应力依赖性的流变来解释库里尔俯冲带的后震后表面变形？在2011年巨大的2011 MW 9.0 Tohoku地震之后，这些问题尤为重要，这使科学家质疑大地震的常规前体的有效性：地震缝隙的位置和浅绿色的位置（俯冲界面处高摩擦锁定的斑块）。