Determining Histories of Slip on Normal Faults With Bedrock Scarps Using Cosmogenic Nuclide Exposure Data
Determining Histories of Slip on Normal Faults With Bedrock Scarps Using Cosmogenic Nuclide Exposure Data
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DOI：
10.1029/2020tc006457
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发表时间：
2021-01
期刊：
影响因子：
4.2
通讯作者：
H. Goodall;L. C. Gregory;L. Wedmore;K. J. W. McCaffrey;R. Amey;G. Roberts;Richard Shanks;R. Phillips;Andrew Hooper
中科院分区：
文献类型：
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作者：
H. Goodall;L. C. Gregory;L. Wedmore;K. J. W. McCaffrey;R. Amey;G. Roberts;Richard Shanks;R. Phillips;Andrew Hooper
宇宙成因暴露数据可用于计算具有暴露基岩陡坎的正断层上随时间变化的断层滑动速率。该方法依赖于与悬崖如何保存有关的假设，这些假设在沿着同一断层的多个位置应该是一致的。以前的工作通常依赖于宇宙成因的数据从一个单一的样本地点，以确定滑动速率的故障。在这里，我们表明，通过应用严格的采样标准，并使用贝叶斯推理马尔可夫链蒙特卡罗方法中的地质建模参数，可以在同一断层上的多个站点模拟类似的滑动率变化模式。因此，宇宙成因数据可用于解决沿沿着走向断层活动。我们目前宇宙成因的36 Cl浓度从七个网站上的两个故障在意大利亚平宁山脉。坎波费利切断层上不同地点的平均滑动速率不同（0.84 ± 0.23至1.61 ± 0.27 mm yr−1），所有地点都经历了0.5至2 ka之间高于平均滑动速率的时期和3 ka之前低于平均滑动速率的时期。在罗卡波罗断层上，断层中心的滑动速率为0.55 ± 0.11毫米/年，断层尖端的滑动速率为0.35 ± 0.05毫米/年。在同一断层沿着，距离上次地震的估计时间是相同的（Campo Felice为631 ± 620年，Roccaptello为2，603 ± 1，355年）。这些结果突出了宇宙成因暴露数据的潜力，以揭示详细的千年历史的地震滑动活动的正断层。
Cosmogenic exposure data can be used to calculate time‐varying fault slip rates on normal faults with exposed bedrock scarps. The method relies on assumptions related to how the scarp is preserved, which should be consistent at multiple locations along the same fault. Previous work commonly relied on cosmogenic data from a single sample locality to determine the slip rate of a fault. Here we show that by applying strict sampling criteria and using geologically informed modeling parameters in a Bayesian‐inference Markov chain Monte Carlo method, similar patterns of slip rate changes can be modeled at multiple sites on the same fault. Consequently, cosmogenic data can be used to resolve along‐strike fault activity. We present cosmogenic 36Cl concentrations from seven sites on two faults in the Italian Apennines. The average slip rate varies between sites on the Campo Felice Fault (0.84 ± 0.23 to 1.61 ± 0.27 mm yr−1), and all sites experienced a period of higher than average slip rate between 0.5 and 2 ka and a period of lower than average slip rate before 3 ka. On the Roccapreturo fault, slip rate in the center of the fault is 0.55 ± 0.11 and 0.35 ± 0.05 mm yr−1 at the fault tip near a relay zone. The estimated time since the last earthquake is the same at each site along the same fault (631 ± 620 years at Campo Felice and 2,603 ± 1,355 years at Roccapreturo). These results highlight the potential for cosmogenic exposure data to reveal the detailed millennial history of earthquake slip on active normal faults.