Seismic hazard assessment of slow active fault zones is challenging as usually only a few decades of sparse instrumental seismic monitoring is available to characterize seismic activity. Tectonic features linked to the observed seismicity can be mapped by seismic imaging techniques and/or geomorphological and structural evidences. In this study, we investigate a seismic lineament located in the Swiss Alpine foreland, which was discussed in previous work as being related to crustal structures carrying in size the potential of a magnitude M 6 earthquake. New, low-magnitude (−2.0 ≤ ML ≤ 2.5) earthquake data are used to image the spatial and temporal distribution of seismogenic features in the target area. Quantitative and qualitative analyses are applied to the waveform dataset to better constrain earthquakes distribution and source processes. Potential tectonic features responsible for the observed seismicity are modelled based on new reinterpretations of oil industry seismic profiles and recent field data in the study area. The earthquake and tectonic datasets are then integrated in a 3D model. Spatially, the seismicity correlates over 10–15 km with a N–S oriented sub-vertical fault zone imaged in seismic profiles in the Mesozoic cover units above a major decollement on top of the mechanically more rigid basement and seen in outcrops of Tertiary series east of the city of Fribourg. Observed earthquakes cluster at shallow depth (<4 km) in the sedimentary cover. Given the spatial extend of the observed seismicity, we infer the potential of a moderate size earthquake to be generated on the lineament. However, since the existence of along strike structures in the basement cannot be excluded, a maximum M 6 earthquake cannot be ruled out. Thus, the Fribourg Lineament constitutes a non-negligible source of seismic hazard in the Swiss Alpine foreland.

中文翻译：

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慢速活动断层带的多尺度成像：对改进瑞士高山前陆地震危险性评估的贡献

缓慢活动断裂带的地震危险性评估具有挑战性，因为通常只有几十年的稀疏仪器地震监测才能表征地震活动。可以通过地震成像技术和/或地貌和结构证据来绘制与观测到的地震活动有关的构造特征。在这项研究中，我们调查了位于瑞士阿尔卑斯山前陆的地震线，在先前的工作中曾讨论过这种地震线与地壳结构有关，该地壳结构的大小可能会引起M 6级地震。新的低震级（-2.0≤ML≤2.5）地震数据用于对目标区域中的地震成因特征进行时空分布成像。对波形数据集进行定量和定性分析，以更好地约束地震分布和震源过程。基于对石油工业地震剖面的新重新解释和研究区域的最新现场数据，对造成观测地震活动的潜在构造特征进行了建模。然后将地震和构造数据集整合到3D模型中。在空间上，地震活动与10-15 km以上的地震有关，与一个N-S定向的亚垂直断层带相关，该带在机械上较坚硬的地下室顶部较大弯折之上的中生代盖层单元的中剖面中的地震剖面中成像，并在第三系东部的露头中看到弗里堡市。观察到的地震聚集在沉积覆盖层的浅深度（<4 km）。给定所观察到的地震活动的空间扩展，我们推断出可能在沿线上发生中等规模的地震。然而，由于不能排除地下室中沿走向构造的存在，因此不能排除最大的M 6地震。因此，弗里堡风貌是瑞士阿尔卑斯山前陆地区不可忽视的地震危险源。