Collaborative Research: Hikurangi Ocean Bottom Investigation of Tremor and Slow Slip (HOBITSS)

合作研究：Hikurangi 海底地震和慢滑移调查 (HOBITSS)

• 批准号: 1334654
• 负责人: Laura Wallace
• 金额: $ 38万
• 依托单位: University of Texas at Austin
• 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: 2013-11-01 至 2016-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1334654&HistoricalAwards=false
• 关键词: Collaborative; Research; Hikurangi; Ocean; Bottom

Deployment of a network of pressure gauges and seismometers on the Hikurangi portion of the subduction zone off North Island New Zealand is designed to record a slow-slip event (SSE) expected to occur on the plate boundary fault in the 2014-2015 timeframe. SSE occur every ~18 months in this region, so documenting the deformation associated with this type of event and comparing that couple-week activity with ongoing microseismicity should illustrate the evolution of forces and associated hazards in this region. Twenty US seafloor instruments, including 10 from OBSIP, will be combined with a similar number of Japanese instruments for ~12 months. These data will be evaluated together with data from onshore geodetic and seismic stations in this international collaboration. Results will inform planning for possible future seafloor drilling by IODP and subsequent in-situ measurements.Due to the shallow dip of the subducting plate, the Hikurangi site offers a unique opportunity to document the small signals associated with SSE, for which motion is too minor for human perception. Insights into this newly-recognized mode of plate interaction are expected to be applicable to other convergent margins. How far 'up-dip' the slip extends, whether all the way to the seafloor near the subduction trench or not, is a key unknown in current estimates of earthquake shaking and tsunami hazard. The extent of slow slip can indicate how much stress on the plate boundary fault is relieved versus building up toward an eventual megathrust earthquake.

在新西兰北岛外俯冲带的Hikurangi部分部署了一个压力计和地震仪网络，旨在记录预计在2014-2015年期间发生在板块边界断层上的慢滑事件（SSE）。SSE在该地区每18个月发生一次，因此记录与此类事件相关的变形，并将两周的活动与正在进行的微震活动进行比较，应该说明该地区的力量演变和相关危害。20台美国海底仪器，其中10台来自OBSIP，将与类似数量的日本仪器结合使用约12个月。在这项国际合作中，这些数据将与陆上大地测量站和地震站的数据一起进行评估。结果将为未来可能通过IODP进行海底钻探和随后的原位测量提供信息。由于俯冲板块的浅倾角，Hikurangi站点提供了一个独特的机会来记录与SSE相关的小信号，这些信号的运动对于人类感知来说太小了。对这种新认识的板块相互作用模式的见解预计将适用于其他收敛边缘。在目前对地震和海啸危险的估计中，“上倾”滑动延伸多远，是否一直延伸到俯冲沟附近的海底，是一个关键的未知因素。慢滑的程度可以表明，板块边界断层上的应力得到了多大程度的缓解，而不是最终形成的大逆冲地震。