The possible transition of brittle failure to an aseismic process due to alteration of juvenile fluids in the NW-Bohemia/ Vogtland earthquake swarm region

在目前的情况下，由于震群的发生遵循典型的扩散特征，因此在西北-波希米亚/沃格特兰地区的震群活动被解释为孔隙流体压力变化的结果。我们将这些结果应用于我们的震群触发模型，但我们不能解释这些超压流体的触发效应起源于上地幔的岩浆储集层。我们的初步研究表明，必要的孔隙流体压力脉冲是由水文事件(暴雨、积雪融化)引起的地表压力瞬变。根据相互连接的管道、断裂带的局部水力扩散率，从最上面的地下水库到震中的孔压扩散过程需要几个月的时间。我们的初步结果是基于两个长期数据集的分析和对比：Bad Brambach矿泉流量约30年的连续记录和这一时期诺伊克斯泰尔震中区的震群活动。这一重要结果支持了水震活动是本区震群活动的主要触发机制的假说。这个项目的主要目标是详细调查和验证这一假说，特别是对每个震中集群及其断裂带。此外，由于破裂过程中热力学P-T条件的变化，沿剪切带的额外孔压脉冲的研究将被视为理解完整触发过程的一个特定目标。除了触发过程外，当地震群周期的近似将被用作进一步的重要假设，以建立一个简化的震群活动长期预报系统，以减轻该地区的灾害。

At the present state, the earthquake swarm activities at the NW-Bohemia/Vogtland region are interpreted as results of pore fluid pressure changes because the occurrence of earthquake swarms follow a diffusion-typical signature. We apply these results for our earthquake swarm trigger model but we prevent the explanation that these trigger effects of over-pressurized fluids are originated at magmatic reservoirs in the upper mantle. Our preliminary investigations suggest significant results that the necessary pore fluid pressure pluses are pressure transients from the surface which are induced by hydrological events (heavy rain, snowmelt). This pore pressure diffusion process from the uppermost groundwater reservoirs to the hypocenters needs several months according to the local hydraulic diffusivity of the interconnected conduits, the fault zones. Our preliminary results base on the analysis and correlation of two long term data sets: the continuously record of the Bad Brambach mineral spring discharge of about 30 years and the earthquake swarm activity of the Nový Kostel epicentral area at this period. The significant results give reason to the hypothesis that hydroseismicity can be considered as main trigger mechanism of the earthquake swarm activity at our area of investigation. The main goal of this project is to investigate and verify this hypothesis in detail, in particular for each epicentral cluster with their fault zones. Further, an investigation of additional pore pressure pulses along the shear zones due to the variations of the thermodynamic P-T-conditions during the rupture process will be considered as one specific target to understand the complete trigger processes. Besides the trigger processes, the approximation of the local earthquake swarm cycles will be used as a further important presumption to install a simplified long-term forecast system of the earthquake swarm activity for hazard reduction in that region.