Abstract
The Eastern Gulf of Corinth (EGoC) is one of the most seismically active areas in Greece. It is monitored by local and regional seismic stations of the Hellenic Unified Seismic Network (HUSN). In 2020, a high-yield seismic sequence, lasting over five months, occurred at the Perachora peninsula. This provided a unique opportunity to investigate the anisotropic properties of the upper crust in the area, which lacks relevant studies. The sequence exhibited characteristics of a seismic swarm, with the strongest event having a magnitude of 3.7. In the herein analysis, we use recordings from suitable HUSN stations for two periods: (a) 2008 to 2019, a period of scarce seismicity, to identify background anisotropy and (b) the 2020 seismic swarm period. We used a fully automated method to measure shear-wave splitting properties. After considering a shear-wave window of 45° and several quality criteria, we determined a complex state of anisotropy, with NE-SW directions of polarization (𝜑) prevailing pre-2020, while a dominant WNW-ESE orientation was observed during the swarm (with secondary NE-SW and N-S trends). The spatial distribution of 𝜑 did not offer any strong correlation with local faults. Additionally, 𝜑 seemed to rotate in 2015 and 2020, with variations of normalized time-delays being present during the crisis. These observations, along with indications regarding fluid diffusion during the swarm, led us to hypothesize that shear-wave splitting in the EGoC is mainly driven by high pressure gradients. A better understanding of pre‑2020 seismicity and more local stations to record future seismicity would be required to further specify the connection between fluid processes and seismic anisotropy in the area.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.