Collaborative Research: Strain Rate and Moment Accumulation Rate along the San Andreas Fault System from InSAR and GPS

合作研究：InSAR 和 GPS 沿圣安地列斯断层系统的应变率和力矩累积率

• 批准号: 1147435
• 负责人: David Sandwell
• 金额: $ 22万
• 依托单位: University of California-San Diego Scripps Inst of Oceanography
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-06-15 至 2015-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1147435&HistoricalAwards=false
• 关键词: Collaborative; Research; Strain; Rate; Moment

The San Andreas Fault System (SAFS) is a natural laboratory for investigating the physics of the earthquake cycle along a major continental transform boundary. Two of the key parameters that can be used for seismic hazard assessment are seismic moment accumulation rate and strain accumulation rate. The GPS component of the Plate Boundary Observatory (PBO) provides accurate vector velocities ( 1 mm/yr accuracy) at a spacing of 10 to 20 km along the SAFS. However, the velocity gradient (strain rate) varies most rapidly within 20 km of the major faults, so strain rate is not well resolved by the GPS data alone. Radar interferometry (InSAR) provides deformation maps at 100 m spatial resolution, although factors such as temporal decorrelation and atmospheric path errors have made it difficult to achieve this full resolution with sufficient precision to improve upon the GPS measurements. The L-band data provided by the ALOS satellite (JAXA) retains phase coherence over longer time intervals than the prior C-band missions. This improvement, combined with stacking techniques to reduce atmospheric errors, now makes it possible to image the entire SAFS using InSAR with unprecedented spatial coverage and resolution.The primary focus of this research is to construct high spatial resolution vector surface deformation measurements by combining the high accuracy point measurements provided by PBO GPS data with the high spatial resolution InSAR measurements available through WInSAR from foreign and domestic SAR missions. The research has four main objectives:- Resolve secular plate boundary deformation using new GPS and InSAR measurements provided by EarthScope (PBO and WInSAR). This involves the development of community software to preprocess the new data streams to be provided by the ALOS-2 and Sentinel-1 InSAR satellites (2013 launch);- Use an integrated GPS-4D model-InSAR technique to better constrain fault slip rates and determine the depth of the locked/creeping transition on active faults of the SAFS;- Generate high-resolution estimates of strain rate and seismic moment rate along major faults of the SAFS; and- Explore methods for isolating non-tectonic deformation contributions common in both InSAR and GPS data.Non-technical summaryIs California prepared for the next big earthquake? Estimates of earthquake potential along major faults, such as the San Andreas Fault System (SAFS), are used for developing scenario earthquakes, for setting regional building codes, and for setting earthquake insurance rates. While the timing of a major earthquake cannot be accurately predicted, the moment magnitude can be accurately estimated from geodetic measurements of present-day crustal deformation. The current array of 700 continuously operating GPS stations in western North America does not completely resolve the crustal deformation gradients (strain) along the major faults because the average station spacing is too large. This research is refining the crustal deformation measurements by computing and modeling the synthetic aperture radar data (SAR) archived at the Western North America InSAR consortium (WInSAR) and the Alaska Satellite Facility. This involves the generation and archive of large-scale (1000 km scale) crustal deformation grids at 0.5 km spatial resolution in a near-automatic fashion. Funding from this grant is supporting two Ph.D. students at SIO and UTEP (a Hispanic Serving Institute) and is being used for further development of undergraduate and graduate courses. This funding is also being used to develop a ?How InSAR Works? module for use in IRISʼs Active Earth interactive kiosks on display around the country. In addition, funding is being used to move the GMTSAR software into the GMT distribution system where it is available to 15,000 users worldwide. We are distributing all high-resolution vector deformation data and maps to the scientific community and archive the results at UNAVCO.

圣安德烈亚斯断层系统（SAFS）是研究沿着大陆转换边界地震周期物理学的天然实验室。地震矩累积率和应变累积率是地震危险性评估的两个关键参数。板块边界观测站的全球定位系统部分提供了沿南亚板块边界沿着10至20公里间距的精确矢量速度（1毫米/年精度）。然而，速度梯度（应变率）变化最快的20公里内的主要故障，所以应变率是不能很好地解决了GPS数据。雷达干涉测量法（干涉合成孔径雷达）提供了100米空间分辨率的变形图，尽管诸如时间去相关和大气路径误差等因素使得难以以足够的精度实现这一全分辨率，以改进全球定位系统测量。ALOS卫星（日本宇宙航空研究开发机构）提供的L波段数据在比以前的C波段飞行任务更长的时间间隔内保持相位相干性。这一改进，结合叠加技术，以减少大气误差，本研究的主要目的是将PBO GPS数据提供的高精度点测量值与国外WInSAR提供的高空间分辨率干涉合成孔径雷达测量值相结合，构建高空间分辨率的矢量地表形变测量值，并将其应用于卫星遥感影像中。国内搜救任务- 利用新的全球定位系统和EarthScope提供的干涉合成孔径雷达测量结果（PBO和W干涉合成孔径雷达），解决长期板块边界变形问题。这涉及开发社区软件，对ALOS-2和Sentinel-1干涉合成孔径雷达卫星提供的新数据流进行预处理- 使用综合GPS-4D模型-InSAR技术，以更好地限制断层滑动速率，并确定SAFS活动断层上锁定/蠕动过渡的深度;- 生成沿着SAFS主要断层的应变率和地震矩率的高分辨率估计值;探索隔离干涉合成孔径雷达和全球定位系统数据中常见的非构造变形影响的方法。技术概述加州为下一次大地震做好准备了吗？对圣安德烈亚斯断层系统（SAFS）等主要断层沿着地震潜力的估计用于制定地震情景、制定区域建筑规范以及制定地震保险费率。虽然大地震发生的时间无法准确预测，但矩震级可以通过对现今地壳变形的大地测量准确估计。目前在北美西部有700个连续运行的全球定位系统台站，但由于平均台站间距太大，它们不能完全分辨出沿着主要断层的地壳形变梯度（应变）。这项研究是通过计算和模拟在北美西部干涉合成孔径雷达联合会（W干涉合成孔径雷达）和阿拉斯加卫星设施存档的合成孔径雷达数据（SAR）来改进地壳变形测量。这涉及以近乎自动的方式生成和存档0.5公里空间分辨率的大规模（1 000公里尺度）地壳形变网格。该基金资助两名博士。SIO和UTEP（西班牙裔服务学院）的学生，并被用于进一步开发本科和研究生课程。这笔资金也被用于开发一个？干涉合成孔径雷达是如何工作的？用于IRIS #700;的Active Earth交互式信息亭的模块在全国各地展出。此外，还利用资金将全球监测和搜索系统软件转移到全球监测和搜索系统分发系统，供全世界15 000名用户使用。我们正在向科学界分发所有高分辨率矢量变形数据和地图，并将结果在联合国志愿人员组织存档。