A Comprehensive Analysis of Geodetic Slip-Rate Estimates and Uncertainties in California
A Comprehensive Analysis of Geodetic Slip-Rate Estimates and Uncertainties in California
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DOI：
10.1785/0120170159
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发表时间：
2018-02-01
影响因子：
3
通讯作者：
Evans, Eileen L.
中科院分区：
文献类型：
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作者：
Evans, Eileen L.
建立一个全面的构造大陆变形模型需要评估(1)断层滑动率，(2)离断层变形率，以及(3)现实的不确定性。断层滑动率可以通过对断层系统进行建模来估算，该建模基于对地表活动位移的空间大地测量，如全球导航卫星系统（GNSS）和干涉合成孔径雷达（In-SAR）。由于测量和认知（模型）的不确定性，大地滑动率估计可能会有很大差异，这对估计滑动率和准确描述不确定性提出了挑战：模型可能在所表示的断层数量和这些断层的精确位置上有所不同。自2003年以来，33个已发表的大地形变模型产生了加州的滑动率估计。这些模型之间的变异性代表了有效模型选择之间的变异性，可以认为是大地滑动率估计中模型不确定性的代表。为了在大地测量滑动率估计之间进行严格的比较，我结合了地理参考网格上的模型，发现在542个网格单元（平均面积为1304公里/单元）中，滑动率的平均标准差接近1.5毫米/年。此外，在所有33项研究中，在每个网格单元中，平均走滑和张滑率可以被投影到统一加州地震破裂预报（UCERF） v.3.1断层上，以形成一个单一的大地测量滑动率汇总模型。不能完全投射到UCERF3.1断层上的滑动速率形成了非模型断层（OMF）变形的总结模型。大多数OMF变形发生在与UCERF3.1断层相交的网格单元中，这表明断层外变形可能在一定程度上是大地滑动率估计中认知不确定性的产物，并且可能在物理上被容纳在UCERF断层上或非常靠近UCERF断层。
Developing a comprehensive model of tectonic continental deformation requires assessing (1) fault-slip rates, (2) off-fault deformation rates, and (3) realistic uncertainties. Fault-slip rates can be estimated by modeling fault systems, based on space geodetic measurements of active surface ground displacement such as Global Navigation Satellite Systems (GNSS) and Interferometric Synthetic Aperture Radar (In-SAR). Geodetic slip-rate estimates may vary widely due to measurement and epistemic (model) uncertainties, presenting a challenge for both estimating slip rates and accurately characterizing uncertainties: models may vary in the number of faults represented and the precise location of those faults. Since 2003, 33 published geodetic deformation models have produced slip-rate estimates within California. Variability among these models represents variability among valid model choices and may be considered a proxy for model uncertainties in geodetic slip-rate estimates. To enable rigorous comparison between geodetic slip-rate estimates, I combine models on a georeferenced grid and find an average standard deviation on slip rate of similar to 1.5 mm/yr over 542 grid cells (average area of 1304 km(2)/cell). Furthermore, the average strike-slip and tensile-slip rates over all 33 studies, in each grid cell, may then be projected onto Unified California Earthquake Rupture Forecast (UCERF) v.3.1 faults for a single summary model of geodetic slip rates. Slip rates that do not project perfectly onto UCERF3.1 faults form a summary model of off-modeled-fault (OMF) deformation. Most of this OMF deformation occurs in grid cells that intersect UCERF3.1 faults, suggesting that off-fault deformation may be, in part, a product of epistemic uncertainty in geodetic slip-rate estimates and may be physically accommodated on, or very near, UCERF faults.