Collaborative Research: Rheology of asthenosphere in the Kuril-Kamchatka subduction zone from postseismic GPS observations after great earthquakes

合作研究：大地震后震后 GPS 观测的千岛堪察加俯冲带软流圈流变学

• 批准号: 1546998
• 负责人: Mikhail Kogan
• 金额: $ 18.5万
• 依托单位: Columbia University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-06-15 至 2017-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1546998&HistoricalAwards=false
• 关键词: Collaborative; Research; Rheology; asthenosphere; Kuril

The project relates to the region of the Kuril subduction zone in the northwest Pacific Ocean subject to disastrous earthquakes. In 2006-2007, a doublet of great (MW 8) earthquakes partly ruptured one of the most conspicuous gaps in subduction-zone seismic activity. An immediate focus of this project is to acquire post-earthquake GPS measurement spanning the time period 2007-2016. These data will allow scientists to better understand the long-term earthquake cycle and will be important for understanding seismic hazards here and in other similar settings. This project will continue and strengthen collaboration between US universities and institutions of the Russian Academy of Sciences. The data provided by the project will be available for use by the broad scientific community. The complete 10-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-Kamchatka subduction zone with the linear viscous mantle or is a stress-dependent rheology required? These problems are especially important after the giant 2011 MW 9.0 Tohoku (Japan) earthquake, which made the scientists question the validity of precursors of imminent large earthquakes: location of seismic gaps (spatial gaps in seismic activity) and location of asperities (patches of high frictional locking at a subduction interface). Observations of postseismic deformation of this length are rare and can significantly improve understanding of the rheology of the mantle. Preliminary results of the 3-D modeling of viscoelastic relaxation now include the effect of slab geometry for linear and nonlinear mantle rheologies with a focus on matching station velocities observed five years and later. The proposed work will extend the modeling efforts based on a significantly increased interval of the data (20% longer). This relatively late stage data is critical in testing the hypothesis of non-linear rheology.

该项目涉及西北太平洋库里尔俯冲带的区域，受到灾难性地震的影响。在2006年至2007年，一场巨大的（MW 8）地震的双打部分破裂了俯冲区域地震活动中最明显的差距之一。该项目的直接重点是获得跨越2007 - 2016年时间段的地球后GPS测量。这些数据将使科学家能够更好地理解长期地震周期，对于在此处和其他类似情况下理解地震危害非常重要。该项目将继续并加强美国大学和俄罗斯科学院机构之间的合作。该项目提供的数据将由广泛的科学界使用。需要完整的10年数据集来解决基本问题：从北美板块下面的太平洋板块（Okhotsk海）下方的俯冲板所建立的菌株已于2006年和2007年在库里尔（Kuril）地震上播出，从而在地球上和后雄性上释放？是否可以用线性粘性地幔解释在Kuril-Kamchatka俯冲带上的地震后表面变形，还是需要应力依赖性流变学？在巨大的2011 MW 9.0 Tohoku（日本）地震之后，这些问题尤其重要，这使科学家质疑即将发生的大地震的前体的有效性：地震差距的位置（地震活动中的空间间隙）和浅绿色的位置（在俯冲界面上的高摩擦锁定斑块）。观察到这一长度的后震动变形很少见，并且可以显着提高对地幔的风湿病的理解。现在，粘弹性弛豫的3-D模型的初步结果包括平板几何形状对线性和非线性地幔流动性的影响，重点是观察到五年及以后的匹配站速度。拟议的工作将根据数据间隔显着增加（长20％），扩大建模工作。该相对较晚的阶段数据对于测试非线性流变学的假设至关重要。