Spatiotemporal pattern of the Santorini - Amorgos 2025 seismic sequence in terms of non additive statistical mechanics

       In January 2025, the area between Santorini and Amorgos experienced the onset of intense seismic activity, with more than 8,500 seismic events of local magnitude ML ≥ 1.5 recorded, and a maximum‑magnitude event of Mw = 5.2. The swarm developed within a complex seismotectonic regime and attracted significant scientific interest because of its proximity to densely populated islands.

In this study, we investigated the spatiotemporal evolution and statistical properties of the seismic swarm to better understand the underlying physical processes, using a dataset extracted from the high-resolution catalogue developed by Fountoulakis et al. (2025), covering the period from 27/01/2025 to 04/03/2025 and including seismic events of magnitude ML ≥ 1.5. The seismic activity initiated beneath the Santorini caldera and progressively migrated northeast towards the Kolumbo submarine volcano and the offshore region of Amorgos, following a NE–SW-trending extensional fault system approximately 60 km long.

    The spatiotemporal analysis revealed two distinct phases of activity, separated by a short transition period (Zaccagnino et al., 2025). The primary phase, from 1 to 9 February 2025, is characterised by rapid spatial expansion and an abrupt increase in the seismicity rate. The secondary phase, from 11 February to 4 March 2025, shows a more coherent migration pattern and a normal decay in the seismicity rate. Using non-additive statistical physics, we estimated the entropic parameters of the inter-event times and distances for both phases and found that they were well described by q-exponential distributions, with entropic parameters qT=1.15, Tq=3.453sec (R2=0.953), qD=0.8 and Dq=4.225Km (R2=0.998) for the primary phase, and qT=1.54, Tq=4.357sec (R2=0.924) and qD=0.72, Dq=8.791Km (R2=0.999) for the secondary phase. These results demonstrate that the 2025 Santorini Amorgos seismic sequence was governed by a non‑additive dynamics, with distinct physical characteristics between the two phases of activity.

References 

Fountoulakis, I., Evangelidis, C. P. (2025). The 2024–2025 seismic sequence in the Santorini-Amorgos region: Insights into volcano-tectonic activity through high-resolution seismic monitoring. Seismica, 4 (1). https://doi.org/10.26443/seismica.v4i1.1663

Zaccagnino, D., Michas, D., Telesca, L., Vallianatos, F. (2025). Precursory patterns, evolution and physical interpretation of the 2025 Santorini-Amorgos seismic sequence, Earth and Planetary Science Letters, 671, 119656. https://doi.org/10.1016/j.epsl.2025.119656.