Modelling the seismic potential of active faults and the associated epistemic uncertainty is a fundamental step of probabilistic seismic hazard assessment (PSHA). We use SHERIFS (Seismic Hazard and Earthquake Rate In Fault Systems), an open-source code allowing us to build hazard models including earthquake ruptures involving several faults, to model the seismicity rates on the North Anatolian Fault (NAF) system in the Marmara Region. Through an iterative approach, SHERIFS converts the slip rate on the faults into earthquake rates that follow a magnitude frequency distribution (MFD) defined at the fault system level, allowing us to model complex multi-fault ruptures and off-fault seismicity while exploring the underlying epistemic uncertainties. In a logic tree, we explore uncertainties concerning the locking state of the NAF in the Sea of Marmara, the maximum possible rupture in the system, the shape of the MFD and the ratio of off-fault seismicity. The branches of the logic tree are weighted according to the match between the modelled earthquake rate and the earthquake rates calculated from the local data, earthquake catalogue and palaeoseismicity. In addition, we use the result of the physics-based earthquake simulator RSQSim to inform the logic tree and increase the weight on the hypotheses that are compatible with the result of the simulator. Using both the local data and the simulator to weight the logic tree branches, we are able to reduce the uncertainties affecting the earthquake rates in the Marmara Region. The weighted logic tree of models built in this study will be used in a following article to calculate the probability of collapse of a building in Istanbul.

中文翻译：

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模拟土耳其马尔马拉地区的地震率和相关不确定性

对活动断层的地震潜力和相关的认知不确定性进行建模是概率地震危险性评估 (PSHA) 的基本步骤。我们使用 SHERIFS（断层系统中的地震灾害和地震率），这是一个开源代码，允许我们构建灾害模型，包括涉及多个断层的地震破裂，以模拟马尔马拉地区北安纳托利亚断层 (NAF) 系统的地震活动率. 通过迭代方法，SHERIFS 将断层上的滑动率转换为遵循断层系统级别定义的震级频率分布 (MFD) 的地震率，使我们能够在探索潜在的地震活动的同时对复杂的多断层破裂和断层外地震活动进行建模认知不确定性。在逻辑树中，我们探讨了有关马尔马拉海 NAF 锁定状态的不确定性，系统中可能发生的最大破裂、MFD 的形状和非断层地震活动的比率。逻辑树的分支根据模拟的地震率与根据当地数据、地震目录和古地震计算的地震率之间的匹配进行加权。此外，我们使用基于物理的地震模拟器 RSQSim 的结果通知逻辑树并增加与模拟器结果兼容的假设的权重。使用本地数据和模拟器对逻辑树分支进行加权，我们能够减少影响马尔马拉地区地震发生率的不确定性。本研究中构建的模型的加权逻辑树将在接下来的文章中用于计算伊斯坦布尔建筑物倒塌的概率。