Developing Methods for Detection and Analysis of Repeating Earthquakes and Low Frequency Earthquakes Using Cascadia Initiative Amphibious Network Data

利用卡斯卡迪亚倡议两栖网络数据开发重复地震和低频地震的检测和分析方法

• 批准号: 1434550
• 负责人: Susan Bilek
• 金额: $ 15.68万
• 依托单位: New Mexico Institute of Mining and Technology
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-08-15 至 2017-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1434550&HistoricalAwards=false
• 关键词: Developing; Methods; Detection; Analysis; Repeating

The Pacific Northwest is subject to earthquake and tsunami hazard associated with the Cascadia subduction zone, due to recurring slip on the plate boundary fault that separates the North America plate and the downgoing Pacific plate. Slip varies in time and space along the fault and understanding the slip patterns can lead to new insights about which fault sections are most likely to produce damaging 'megathrust' events (greater than magnitude 8). By studying smaller events that occur throughout a seismic cycle (loading, rupture, post seismic, reloading etc) this study can provide context for updated regional hazard assessment. An undergraduate intern and a PhD student will receive seismology training using both onshore and offshore data. A portion of the spectrum of slip behaviors along the Cascadia megathrust fault will be studied using seismic data from the Amphibious Array- reoccupied EarthScope Transportable Array sites and OBSIP ocean bottom seismometers. Small repeating earthquakes will be documented for the 4-yr duration of Cascadia Initiative (CI) and their distribution will be interpreted in terms of fault character and possible along-strike variation in structure within the subducting plate. The offshore coverage is expected to eliminate a current bias in observations where onshore-only results suggest that low frequency events (LFE) only occur in the down-dip part of the seismogenic zone. A pilot study confirms that the planned automated spectral detection method can succeed on CI ocean bottom seismometer data. There is potential for shallow repeating events to occur in the up-dip portion of the megathrust zone and there may be variations in level and type of source signature, including possibly new LFE, along the Cascadia subduction zone. A lesson designed for an undergraduate course will be developed and archived on the IRIS InClass and SERC servers. The event catalog and source parameter results will be made available via publication supplements and at least one NSF-supported open database (IEDA).

西北太平洋地区受到与卡斯卡迪亚俯冲带相关的地震和海啸危害，这是由于在板边界断层上反复滑动，将北美板块和下去太平洋板块分开。沿断层的时间和空间有所不同，了解滑移模式可能会导致新见解，即哪些故障部分最有可能产生破坏性的“巨型”事件（大于8幅度）。通过研究整个地震周期中发生的较小事件（负载，破裂，地震后，重新加载等）可以为更新的区域危害评估提供背景。本科实习生和博士生将使用陆上和近海数据接受地震学培训。将使用来自两栖阵列的地震数据来研究沿Cascadia Megathrust断层沿Cascadia Megathrust断层的一部分频谱，并重新占地可转移的可运输阵列位点和粘合海底震震。在Cascadia倡议（CI）的4年持续时间内，将记录小型重复地震，其分布将以断层特征和俯冲板内结构的影响变化来解释。预计海上覆盖范围将消除当前的观测偏差，在观测结果中，仅在陆上的结果表明低频事件（LFE）仅发生在地震生成区的下dip部分。一项试点研究证实，计划的自动光谱检测方法可以在CI海洋底部地震计数据中成功。在大型区域的上浸区的浸入部分中，可能发生浅重复事件，并且在卡斯卡迪亚俯冲带沿线的水平和源签名类型（包括可能是新LFE）的水平和类型可能有所不同。专为本科课程设计的课程将在Iris含的和SERC服务器上开发和存档。事件目录和源参数结果将通过出版补充剂和至少一个NSF支持的开放数据库（IEDA）提供。