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) 是研究沿着主要大陆转换边界的地震周期物理现象的天然实验室。可用于地震危险性评估的两个关键参数是地震矩累积率和应变累积率。板块边界观测站 (PBO) 的 GPS 组件可沿 SAFS 以 10 至 20 公里的间隔提供精确的矢量速度（精度为 1 毫米/年）。然而，在主要断层20公里范围内，速度梯度（应变率）变化最快，因此仅靠GPS数据并不能很好地解析应变率。雷达干涉测量 (InSAR) 提供 100 m 空间分辨率的变形图，尽管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种全分辨率以改进 GPS 测量。 ALOS 卫星 (JAXA) 提供的 L 波段数据比之前的 C 波段任务在更长的时间间隔内保持了相位相干性。这一改进与减少大气误差的叠加技术相结合，现在可以使用 InSAR 以前所未有的空间覆盖范围和分辨率对整个 SAFS 进行成像。这项研究的主要重点是通过结合高空间分辨率矢量表面变形测量来构建高空间分辨率矢量表面变形测量。 PBO GPS 数据提供的精确点测量，以及通过 WInSAR 从国外和国内 SAR 任务获得的高空间分辨率 InSAR 测量。该研究有四个主要目标： - 使用 EarthScope（PBO 和 WInSAR）提供的新 GPS 和 InSAR 测量来解决长期板块边界变形。这涉及开发社区软件来预处理 ALOS-2 和 Sentinel-1 InSAR 卫星（2013 年发射）提供的新数据流； - 使用集成 GPS-4D 模型 - InSAR 技术更好地限制断层滑动率和确定 SAFS 活动断层上锁定/爬行转变的深度；- 生成沿 SAFS 主要断层的应变率和地震矩速率的高分辨率估计； - 探索隔离 InSAR 和 GPS 数据中常见的非构造变​​形贡献的方法。非技术摘要加州是否为下一次大地震做好了准备？对主要断层（例如圣安德烈亚斯断层系统 (SAFS)）沿线地震潜力的估计可用于开发地震情景、制定区域建筑规范以及制定地震保险费率。虽然无法准确预测大地震的时间，但可以通过当今地壳变形的大地测量来准确估计时刻震级。目前北美西部连续运行的 700 个 GPS 站阵列并不能完全解析沿主要断层的地壳变形梯度（应变），因为平均站间距过大。这项研究通过计算和建模北美西部 InSAR 联盟 (WINSAR) 和阿拉斯加卫星设施存档的合成孔径雷达数据 (SAR) 来完善地壳变形测量。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（1000 公里规模）地壳变形网格。这笔赠款的资金用于支持两名博士生。 SIO 和 UTEP（西班牙服务学院）的学生，并被用于本科生和研究生课程的进一步开发。这笔资金还用于开发“InSAR 的工作原理”。该模块用于在全国各地展示的 IRIS Active Earth 交互式信息亭。此外，资金还用于将 GMTSAR 软件转移到 GMT 分发系统中，全球 15,000 个用户可以使用该软件。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，并将结果存档在 UNAVCO 中。