Characterizing source properties of NW Bohemia / Vogtland earthquake swarms exploiting novel network and waveform processing tools (CHASING).

• Applicant: Pinar Buyukakpinar, Ph.D.
• Subject Area: Geophysics
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 517982028

One of the main goals of the ICDP-Eger is to unravel the cause of the earthquake swarms in the NW Bohemia / Vogtland region, understanding the role of fluids or magmas. The most precise way to do this is to accurately record earthquakes and the anatomy and temporal changes of earthquake swarms and compare them with models of earthquake swarm generation. Due to the recently employed unique measurement conditions with a combination of close-meshed seismological bedrock stations with small-scale high-frequency 3D arrays and ICDP monitoring boreholes, it is now possible to gather the necessary source information using innovative approaches for these goals. Since 2020, the 60-channel Landwüst 3D array has already recorded, with a sampling frequency of 1000 Hz, three massive earthquake swarms with thousands of earthquakes at a distance of about 7 km to 30 km. The project aims to design a novel automatic processing to exploit this rich and unique dataset, including waveform-based detection, re-location, and Bayesian full moment tensor inversion. Utilizing template matching and machine learning techniques, we intend to significantly increase the catalog size with a completeness magnitude Mc<-0.5. Moreover, it is purposed to reveal the source characteristics of the smallest micro-earthquakes by applying a relative moment tensor inversion method in combination with the Bayesian moment tensor inversions of larger events. The relative method was applied in the region 25 years ago but never applied to newer data. Empirical Green’s Functions (EGFs) can be extracted based on the recordings of smaller earthquakes during highly clustered earthquake swarms and source time functions (STFs) can be reconstructed. Rupture directions can be estimated from the azimuthal variations of amplitudes of STFs. The combination of the set of relative locations, relative source mechanism, rupture direction changes with fluid-induced seismicity and emplacement models can decipher the processes that lead to earthquake swarms and answer the question of whether swarms in the region have a common origin, and whether the exceptional strong activity beneath Nový Kostel since 1984 indicates that magma penetrated into the upper crust at this location.

• DFG Programme: Infrastructure Priority Programmes
• Subproject of: SPP 1006: International Continental Scientific Drilling Program (ICDP)
• International Connection: Czech Republic, Italy, Spain
• Co-Investigators: Professor Dr. Torsten Dahm; Privatdozent Dr. Sebastian Hainzl; Dr. Sebastian Heimann; Dr. Gesa M. Petersen
• Cooperation Partners: Dr. Flavio Cannavo; Dr. Jana Doubravová; Dr. Josef Horálek; Dr. Jose Angel Lopez Comino, Ph.D.; Dr. Josef Vlcek