BRASS: Bright Reflector Characterisation in a Geodynamically Active Region with Recurring Swarm Seismicity

西波希米亚/沃格特兰地区(WB/V)是一个具有重大构造意义的地区，因为其频繁的微震群。通常情况下，该地区的地震活动释放的能量很低，当地居民感觉不到。然而，在过去十年中，在11月份科斯特尔群区(捷克共和国)发生了几次规模更大的事件。这些事件，加上最近德国沃格特兰微震活动的增加，促使了几项新的研究。到目前为止，已经有许多关于微震群来源的研究。他们中的大多数人认为，从地壳深处迁移的流体聚集并触发了地震。然而，流体的路径尚未确定，也不知道为什么流体聚集在这些位置。因此，这项研究的目的是对震群附近的地下结构进行成像，并对这些结构进行模拟，以确定WB/V区内的整体构造和构造条件。为了实现这一目标，佛雷贝格理工大学地震和地震学工作组的研究人员最近对来自WB/V地区的两条活动震源地震剖面进行了重新处理。这些数据集成像了与震群地震空间相关的明亮反射体。在这项研究中，我将使用反射系数模型来描述在活动地震剖面中观察到的明亮反射体的特征。这些反射体可能代表了地质和/或构造边界，它们圈闭了流体，促进了微地震破裂。最近，我们的工作组成功地使用这种方法对晶体环境中的断层进行了建模和表征。在这里，我将使用这种方法来模拟9HR/91和MVE-90剖面中的明亮反射器，并确定它们是否成像相同的结构。为了模拟和绘制整个WB/V的明亮反射面，将采用这种方法，并将其应用于德国和捷克当地地震仪记录的地震记录。根据模拟结果和反射面地图，我将确定反射层是与群体活动有关，还是代表无关的结构。这项研究将对研究流体和地震之间的关系的科学家们产生兴趣。此外，这种方法将对有兴趣绘制局部地震台网良好但来自活跃震源研究的信息较少的地区的地下结构图的研究人员有用。

The West Bohemia/Vogtland region (WB/V) is an area of significant tectonic interest due to its frequent microseismic swarms. Typically, the seismic activity in this region has a low energy release that it is not felt by the local population. However, over the last decade several larger magnitude events occurred in the Nový Kostel swarm region (Czech Republic). These events, along with a recent increase in microseismic activity in Vogtland (Germany) has motivated several new studies. To date, there have been many studies relating to the source of the microseismic swarms. Most of them proposed that fluids migrating from the deeper crust accumulate and trigger the earthquakes. However, the fluid pathways have not been determined and it is not known why the fluids accumulate in these locations. Therefore, this study aims to image the subsurface structures in the vicinity of the swarm zones, and to model the structures in order to determine the overall structural and tectonic conditions within the WB/V region. In order to achieve this goal, two active source seismic profiles from the WB/V region were recently reprocessed by researchers in the Seismics and Seismology Working Group at TU Bergakademie Freiberg. These datasets imaged bright reflectors spatially correlated with the swarm earthquakes. In this study, I will use reflection coefficient modelling to characterise the bright reflectors observed in the active seismic profiles. These reflectors may represent geological and/or structural boundaries which trap fluids and facilitate the microseismic rupturing. Recently, our working group successfully used this method to model and characterise faults in a crystalline environment. Here, I will use this method to model the bright reflectors in the 9HR/91 and MVE-90 profiles, and to determine if they image the same structures. In order to model and map the bright reflectors throughout WB/V, the method will be adapted and applied to earthquake seismograms recorded by local German and Czech seismometers. Based on the modelling results and the reflector map, I will determine if the reflectors are associated with the swarm activity, or represent unrelated structures. This study will be of interest to scientists studying the relationships between fluids and earthquakes. Furthermore, the methodology will be useful to researchers interested in mapping the subsurface structures in regions with a good local seismic network, but little information from active source studies.