The 2024–2025 seismic sequence in the Santorini-Amorgos region: Insights into volcano-tectonic activity through high-resolution seismic monitoring
DOI:
https://doi.org/10.26443/seismica.v4i1.1663Keywords:
earthquake relocation, automated workflow, moment tensor, volcano seismology, machine learningAbstract
The 2024–2025 seismic sequence in the Santorini-Amorgos region demonstrates a complex evolution revealing the interaction between tectonic and volcanic processes. In this study, a detailed seismic catalog is presented, generated for operational monitoring using machine-learning-based phase picking and high-precision relocation methods. By late summer 2024, seismic activity emerged beneath Santorini and within the caldera. By late January 2025 the seismicity appeared at around 20 km beneath the Kolumbo volcano before migrating northeastward and shallower around Anydros island, aligning with southwest-northeast tectonic structures. The relocation process confirmed a diffuse back-and-forth migration along this trend, with some distinct shallow events. Non-double couple moment tensor solutions show predominantly positive isotropic components suggesting crack-opening processes driven by magmatic and fluid involvement. Spectral analysis metrics also support this, highlighting earthquake spatial variations with different frequency content linked to alternative source mechanisms. The results show a complex interaction between tectonic and magmatic processes, potentially indicating the upward migration of magmatic fluids from deep reservoirs or dike injection. Overall, during this intense seismovolcanic activity, we established an operational workflow to provide the authorities with updates on the ongoing evolution of this earthquake sequence. This high quality seismic catalog is now openly available for future studies.
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