Interseismic strain accumulation across the central North Anatolian Fault from iteratively unwrapped InSAR measurements
Interseismic strain accumulation across the central North Anatolian Fault from iteratively unwrapped InSAR measurements
复制标题
DOI：
10.1002/2016jb013108
复制
发表时间：
2016-12-01
影响因子：
3.9
通讯作者：
Bekaert, David P. S.
中科院分区：
文献类型：
--
作者：
Hussain, Ekbal;Hooper, Andrew;Bekaert, David P. S.
北安纳托利亚断层（NAF）是中东的一个主要构造特征，也是土耳其最活跃的断层。 NAF 的中心部分是全球导航卫星系统 (GNSS) 稀缺的区域。先前对震间形变的研究主要集中在伊斯梅特帕夏镇附近的地震蠕变上，使用在单一视线方向上获取的雷达数据，需要几个建模假设。我们使用 2003 年至 2010 年间获取的 Envisat 卫星任务的上升和下降数据测量了整个 NAF 的震间变形。我们不是拒绝干涉图中错误展开的区域，而是开发了一种新的迭代展开程序，用于小基线干涉合成孔径雷达 (InSAR) 处理，扩大了空间覆盖范围。我们的方法迭代地纠正展开错误并提高展开过程的鲁棒性。我们使用 GNSS 观测结果从 InSAR 数据中去除长波长趋势，并将 InSAR 速度解卷积为断层平行运动。断层平行速度剖面显示，在大约 200 公里的距离内，断层滑移率系统性地向东下降，从 30 毫米/年（25-34，95% 置信区间 (CI)）降至 21 毫米/年（14-27，95% CI）。跨断层的直接偏移测量揭示了断层沿 NAF 中部类似 130 公里的部分蠕变，平均蠕变速率为 8 +/- 2 毫米/年，最大蠕变速率为 14 +/- 2 毫米/年，位于伊斯梅特帕夏以东 30 公里处。由于断层蠕变仅释放了浅层地壳长期应变的 30-40%，因此该断层仍然能够在该地区产生大型破坏性地震。
The North Anatolian Fault (NAF) is a major tectonic feature in the Middle East and is the most active fault in Turkey. The central portion of the NAF is a region of Global Navigation Satellite Systems (GNSS) scarcity. Previous studies of interseismic deformation have focused on the aseismic creep near the town of Ismetpasa using radar data acquired in a single line-of-sight direction, requiring several modeling assumptions. We have measured interseismic deformation across the NAF using both ascending and descending data from the Envisat satellite mission acquired between 2003 and 2010. Rather than rejecting incorrectly unwrapped areas in the interferograms, we develop a new iterative unwrapping procedure for small baseline interferometric synthetic aperture radar (InSAR) processing that expands the spatial coverage. Our method corrects unwrapping errors iteratively and increases the robustness of the unwrapping procedure. We remove long wavelength trends from the InSAR data using GNSS observations and deconvolve the InSAR velocities into fault-parallel motion. Profiles of fault-parallel velocity reveal a systematic eastward decrease in fault slip rate from 30 mm/yr (25-34, 95% confidence interval (CI)) to 21 mm/yr (14-27, 95% CI) over a distance of similar to 200 km. Direct offset measurements across the fault reveal fault creep along a similar to 130 km section of the central NAF, with an average creep rate of 8 +/- 2 mm/yr and a maximum creep rate of 14 +/- 2 mm/yr located similar to 30 km east of Ismetpasa. As fault creep is releasing only 30-40% of the long-term strain in the shallow crust, the fault is still capable of producing large, damaging earthquakes in this region.