Variations of seismic b-value at different stages of the seismic cycle along the North Anatolian Fault Zone in northwestern Turkey
Variations of seismic b-value at different stages of the seismic cycle along the North Anatolian Fault Zone in northwestern Turkey
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DOI：
10.1016/j.tecto.2017.05.028
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发表时间：
2017-08
期刊：
影响因子：
2.9
通讯作者：
C. Raub;P. Martínez‐Garzón;G. Kwiatek;M. Bohnhoff;G. Dresen
中科院分区：
文献类型：
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作者：
C. Raub;P. Martínez‐Garzón;G. Kwiatek;M. Bohnhoff;G. Dresen
我们研究了土耳其西北部北安纳托利亚断裂带(NAFZ)的时空变化，重点是1999年Izmit和Düzce组合破裂以及马尔马拉东部海。我们使用了伊兹米特-杜兹斯地区当地的地震活动目录，涵盖了伊兹米特地震前2.5年到杜兹塞主震后14个月的时间跨度，以及马尔马拉海东部四年的震源目录。我们始终如一地计算矩大小，以确保数据集均匀，并应用严格的质量标准。这使得研究整个地区和地震周期不同阶段的B值的变化成为可能。用标准网格法绘制了深度剖面图和时间序列图，揭示了研究区内b值分布的不均一性。B值观测的多样性不能被明确地解释，因为b值很可能取决于断裂带特征的组合，如局部应力条件、地壳的非均质性和损伤分布。通过提出一套全面的可能的解释，我们指出，对结果偏向于压力或另一个单独参数的讨论可能会导致错误的结论。此外，应用的数据离散化方案会影响最终b值分布的外观，从而导致潜在的误解。
We studied spatiotemporalb-value variations along the North Anatolian Fault Zone (NAFZ) in northwestern Turkey with a focus on the combined 1999 Izmit and Düzce rupture and the eastern Sea of Marmara. We used a local seismicity catalog of the Izmit-Düzce region covering a time span from 2.5 years prior to the Izmit until 14 months after the Düzce mainshock and a four-year hypocenter catalog in the eastern Sea of Marmara. We consistently calculated moment magnitudes to ensure a homogeneous dataset and applied strict quality criteria. This allows studying variations ofb-values throughout the region and at different stages of the seismic cycle. With a standard gridding techniqueb-value maps, depth sections and time series were calculated which reveal a very heterogeneousb-value distribution in the study area. The variety ofb-value observations cannot be interpreted unambiguously, given that theb-value most likely depends on a combination of fault-zone characteristics like local stress conditions, heterogeneity of the crust and damage distribution. By presenting a comprehensive set of possible interpretations we point out that a biased discussion of the results towards stress or another individual parameter may lead to erroneous conclusions. Furthermore, the applied data discretization scheme influences the appearance of the finalb-value distribution leading to potential misinterpretations.