A proposed study of the dynamics of the Hikurangi New Zealand margin.

拟对希库朗吉新西兰边缘的动态进行研究。

• 批准号: 1753660
• 负责人: Harlan Johnson
• 金额: $ 30万
• 依托单位: University of Washington
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-04-01 至 2022-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1753660&HistoricalAwards=false
• 关键词: proposed; study; dynamics; Hikurangi; New

This multi-disciplinary study will investigate the processes that trigger submarine slope failures on the New Zealand continental margin. The investigation will explore how many failures occur and their frequency, whether small landslides in an area make the slope resistant to large landslides, and what types of landslides generate tsunamis. Recent work off the northwest coast of the U.S. has shown that small landslides on continental margins occur more frequently than previously thought. The small landslides are caused by shaking generated by both local and remote earthquakes. Changes in the overlying water column were also found to be important in generating the small landslides. In this new study off New Zealand, seafloor sensor data will be combined with other available geophysical, water column, and meteorological data, to evaluate whether the results of the Cascadia work on the stability of submarine slopes can be generalized to other subduction zone margins. The results of this study will improve the capability to identify past large earthquakes in the sedimentary record. In addition, this study will provide constraints for models of submarine landslides and aid in predicting areas of potential slope failure. The study supports the training of a postdoctoral investigator.Accretionary margins that overlie active subduction zones undergo continuous re-surfacing by repeated sediment slope failures and gravity flows. Studies done off Cascadia show that slope failures can occur either spontaneously or be triggered by identifiable events that include oceanographic processes or by seismic waves generated by local or remote earthquakes. The mechanisms and key attributes of these triggering seismic waves (e.g., frequency content, duration, etc.) remain speculative. Preliminary results also indicate that the geologic structure and topography of the accretionary wedge have profound impacts on the seismic loading. Sediment slope failures and flows also can be triggered by storms, tides, upper water column eddies and circulation changes. This study tests these ideas by analyzing new data from seafloor sensors that were deployed on the Hikurangi margin off New Zealand in 2015. These data will also be used to examine the signature of slow slip events on the shallow plate interface. A Regional Ocean Modeling System hindcast will provide insight into the nature of signals at the seafloor that originate from ocean surface forcing in this area. By combining seafloor pressure, temperature and seismic ground motion measurements, with other available geophysical, water column and meteorological data, and the oceanographic context provided by the regional model, it will be possible to improve the fidelity of seafloor temperature and pressure signals associated with sediment slope failures and flows, with the side-benefit of characterizing near-surface eddies and ocean circulation changesThis award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

这项多学科研究将调查引发新西兰大陆边缘海底斜坡破坏的过程。这次调查将探讨有多少破坏发生和它们的频率，一个地区的小滑坡是否使斜坡抵抗大滑坡，以及哪种类型的滑坡会产生海啸。最近对美国西北海岸的研究表明，大陆边缘的小型山体滑坡发生的频率比以前想象的要高。小型滑坡是由本地和远程地震产生的震动引起的。上覆水柱的变化也被发现是产生小型滑坡的重要因素。在新西兰海域的这项新研究中，海底传感器数据将与其他可用的地球物理、水柱和气象数据相结合，以评估卡斯卡迪亚对海底斜坡稳定性的研究结果是否可以推广到其他俯冲带边缘。这项研究的结果将提高在沉积记录中识别过去大地震的能力。此外，该研究将为海底滑坡模型提供约束条件，并有助于预测潜在的边坡破坏区域。这项研究支持培养一名博士后研究员。位于活动俯冲带上的增生边缘通过反复的沉积物斜坡破坏和重力流不断地重新表面化。在卡斯卡迪亚进行的研究表明，边坡破坏既可能是自发发生的，也可能是由可识别的事件引发的，包括海洋过程，也可能是由当地或偏远地震产生的地震波引发的。这些触发地震波的机制和关键属性（例如，频率内容，持续时间等）仍然是推测性的。初步结果还表明，吸积楔的地质构造和地形对地震荷载有深远的影响。泥沙斜坡的破坏和流动也可能由风暴、潮汐、上层水柱涡流和环流变化引发。这项研究通过分析2015年部署在新西兰Hikurangi边缘的海底传感器的新数据来验证这些想法。这些数据还将用于研究浅层板块界面上慢滑事件的特征。区域海洋模拟系统的后预报将使我们深入了解该地区源自海洋表面强迫的海底信号的性质。通过将海底压力、温度和地震地面运动测量与其他可用的地球物理、水柱和气象数据以及区域模式提供的海洋学背景结合起来，就有可能提高与沉积物斜坡破坏和流动有关的海底温度和压力信号的保真度。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。