RAPID: Observations of Vertical Deformation From Tidal Time Series for the 2010 Slow Slip Event in Cascadia

RAPID：2010 年卡斯卡迪亚慢滑事件潮汐时间序列垂直变形观测

• 批准号: 1042253
• 负责人: Ray Weldon
• 金额: $ 4.84万
• 依托单位: University of Oregon Eugene
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-07-01 至 2011-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1042253&HistoricalAwards=false
• 关键词: RAPID; Observations; Vertical; Deformation; Tidal

This project will characterize the next slow slip earthquake on the Cascadia Subduction zone interface using uplift measured by a dense network of tide gauges. 12 temporary tide gauges are being deployed on the Olympic Peninsula of Washington, the portion of the Cascadia subduction zone expected to experience a M ~6.5 slow slip earthquake in ~August of 2010. Because the recurrence interval of slow slip on this part of the subduction zone is ~14 months and the ocean is an order of magnitude quieter during the summer, the ~August 2010 event provides an opportunity to catch an event at the calmest time of year that will not recur for at least 7 years. Data from this temporary network and the existing sparse NOAA network of tide gauges are providing a detailed image of the vertical deformation associated with the 2010 event, which is poorly resolved by GPS or seismic techniques that have been used to study the last 12 of these events. The vertical deformation, combined with horizontal deformation from GPS and source location and timing information from seismology, allows us to accurately determine the distribution of slip and the release of strain on the subduction interface. This improved understanding of slip on the deep subduction zone interface will provide the necessary data to build better models that link the time-dependent release of strain along the subduction zone, including the timing and extent of rupture of M~9 megathrust earthquakes that occur on average 300-500 years on the Cascadia subduction zone. It has been speculated that a future slow slip earthquake will trigger the next megathrust earthquake and tsunami, so it is critically important to understand these events and how they relate to damaging seismogenic earthquakes.Undergraduate students from NSF's UCORE program, who are participating in a summer research at the University of Oregon, are carrying out most of the instrument deployments. The UCORE program brings community college students to the University of Oregon to learn to carry out scientific research by actively participating in ongoing projects. The UCORE students are installing and calibrating the tide gauges, downloading and interpreting the data, and will present the results of their work in a formal poster session at the end of the program.In addition to the primary goal of characterizing the 2010 slow slip earthquake, our deployment allows us to calculate the long-term relative sea level change at each site, because most of our sites have been occupied intermittently over the past century. This means we can compare the long term uplift rate to the uplift associated with individual slow slip earthquakes and thus determine how much of the strain provided by plate tectonics is available for megathrust rupture and permanent landscape development. Finally, our project is allowing us to improve our methodology for finding tectonic transients in tidal records, and potentially to apply this method to generate a catalog of slow slip events that extends back ~100 years in this area.

该项目将使用由密集的验潮仪网络测量的隆起来表征卡斯卡迪亚俯冲带界面上的下一次慢滑地震。 正在华盛顿奥林匹克半岛部署12个临时验潮仪，该半岛是卡斯卡迪亚俯冲带的一部分，预计将于2010年8月发生M ~6.5级慢滑地震。 由于俯冲带这一部分缓慢滑动的复发间隔约为14个月，海洋在夏季安静一个数量级，因此2010年8月的事件提供了一个机会，可以在一年中最平静的时候捕捉到至少7年内不会复发的事件。 来自这个临时网络和现有的稀疏NOAA验潮站网络的数据提供了与2010年事件相关的垂直变形的详细图像，这是通过GPS或地震技术来解决的，这些技术已经用于研究最近12次事件。 垂直变形，结合水平变形从GPS和震源位置和定时信息，从地震学，使我们能够准确地确定分布的滑动和应变的释放俯冲界面。 对深俯冲带界面滑移的进一步理解将为建立更好的模型提供必要的数据，这些模型将应变沿着俯冲带随时间的释放联系起来，包括卡斯卡迪亚俯冲带上平均300-500年发生的M~9大逆冲断层地震的破裂时间和程度。 据推测，未来的慢滑地震将引发下一次大推力地震和海啸，因此了解这些事件以及它们与破坏性地震的关系至关重要。美国国家科学基金会UCORE项目的本科生正在参加俄勒冈州大学的夏季研究，他们正在进行大部分仪器部署。 UCORE计划将社区大学的学生带到俄勒冈州大学，通过积极参与正在进行的项目来学习开展科学研究。 UCORE的学生正在安装和校准验潮仪，下载和解释数据，并将在项目结束时在正式的海报会议上展示他们的工作成果。除了描述2010年慢滑地震的主要目标外，我们的部署使我们能够计算每个地点的长期相对海平面变化，因为在过去的世纪，我们的大部分土地都被断断续续地占用。 这意味着我们可以比较长期的隆起率与个别缓慢滑动地震相关的隆起，从而确定板块构造提供的应变中有多少可用于巨型逆冲断层破裂和永久景观发展。 最后，我们的项目使我们能够改进在潮汐记录中寻找构造瞬变的方法，并有可能应用这种方法来生成该地区可追溯到100年前的慢滑事件目录。