Collaborative Research: Constraints on Interseismic Deformation Offshore Oregon from Calibrated Continuous Pressure Records

合作研究：校准连续压力记录对俄勒冈州近海震间形变的约束

• 批准号: 1558477
• 负责人: William Wilcock
• 金额: $ 22.99万
• 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: 2016
• 资助国家: 美国
• 起止时间: 2016-05-15 至 2020-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1558477&HistoricalAwards=false
• 关键词: Collaborative; Research; Constraints; Interseismic; Deformation

The Cascadia Subduction zone lies off the coast of the Pacific Northwest and is of both scientific and public interest because it is the site of catastrophic earthquakes similar to those that have occurred over the last decade in Japan, Chile, and Sumatra. On land, networks of instruments are available to measure the build-up of strain across the Cascadia subduction zone fault. Similar observations are required offshore to understand the dynamics of the subduction zone better, and to place stronger constraints on the earthquakes and tsunamis the fault produces every few hundred years. This project uses calibrated seafloor pressure sensors to make accurate measurements of the elevation of the seafloor at six sites off the coast of central Oregon. The project will initiate a decadal study that will measure changes in seafloor elevation that result from the build-up, and potentially the release, of strain across the subduction zone fault. The study will constrain the width of the locked portion of the fault that will break in the next large subduction zone earthquake. The project will involve two graduate students, and include at least four undergraduates on each research expedition.High-quality offshore vertical geodetic measurements will be used to provide a baseline suitable for resolving secular strain caused by locking across the Cascadia subduction zone, and for detecting slow slip events. Several previous studies have shown that seafloor pressure measurements can detect slow-slip events, but the drift of seafloor pressure sensors has limited their application to measuring secular strain. The University of Washington (UW) and Scripps Institution of Oceanography (SIO) have collaborated to build and successfully test a campaign version of the SIO seafloor calibrated pressure recorder, the Absolute Seafloor Calibrated Pressure Recorder (ASCPR). This instrument measures absolute pressures to an accuracy equivalent to ~1 cm of water depth. Repeat measurements with the ASCPR on stable seafloor benchmarks equipped with a continuously recording bottom pressure gauge will be used to remove the drift from pressure time series and enable measurements of secular strain. The UW and SIO have deployed a trench-perpendicular profile of 6 benchmarks and bottom pressure recorders off central Oregon. This project supports repeat campaign-style absolute pressure measurements over two years on each benchmark to fully characterize the repeatability of ASCPR measurements and initiate a decadal study required to measure secular strain. By utilizing stable, undisturbed benchmarks to make accurate absolute pressure measurements, this effort could transform our capabilities for making long-term geodetic observations offshore. Complementary geodetic and physical oceanographic modeling studies are being used to further understand the expected geodetic signals and develop improved methods to separate geodetic and oceanographic components of pressure.

卡斯卡迪亚俯冲区位于太平洋西北沿海地区，既具有科学和公共利益，因为它是与过去十年在日本，智利和苏门答腊过去十年发生的灾难性地震所在地。在陆地上，可以使用仪器网络来衡量卡斯卡迪亚俯冲带断层的应变的积累。需要类似的观察结果，才能更好地了解俯冲带的动力学，并在地震和海啸上对断层产生更强的约束。 该项目使用校准的海底压力传感器来准确测量俄勒冈州中部六个地点海底的海拔。 该项目将启动一项十年研究，该研究将衡量由俯冲带跨俯冲带断层造成的堆积，可能是释放的海底海拔变化。 该研究将限制断层锁定部分的宽度，这将破坏下一个大型俯冲区地震。该项目将涉及两名研究生，并在每次研究探险中包括至少四名本科生。高质量的垂直测量测量值将用于提供一个基线，适合于解决由锁定Cascadia俯冲区锁定引起的世俗应变的基线，以及检测慢速滑移事件。先前的几项研究表明，海底压力测量可以检测到慢滑动事件，但是海底压力传感器的漂移限制了其在测量世俗应变中的应用。华盛顿大学（UW）和Scripps海洋学研究所（SIO）已合作构建并成功测试了Sio Seafiror校准压力录音机的活动版本，即绝对海底校准的压力录像机（ASCPR）。 该仪器的绝对压力达到相当于〜1 cm的水深的精度。 与ASCPR进行的重复测量在配备有连续记录的底部压力表的稳定海底基准测试上，将用于清除压力时间序列中的漂移，并启用对世俗应变的测量。 UW和SIO部署了俄勒冈州中部的6个基准和底部压力记录器的沟槽垂直轮廓。该项目在两年内支持重复运动风格的绝对压力测量，以充分表征ASCPR测量的重复性，并启动一项测量世俗菌株所需的十年研究。通过利用稳定的，不受干扰的基准来进行准确的绝对压力测量，这项工作可以改变我们在海上进行长期大地测量观测的能力。互补的大地测量和物理海洋学建模研究被用来进一步了解预期的大地测量信号，并开发了改进的方法，以分离压力的大地测量和海洋学成分。