The 2025 Santorini earthquake sequence unveils the tail of the magnitude-frequency distribution

We present a statistical analysis of the intense earthquake swarm near Santorini, Greece, in 2025. A change-point analysis of the b -value of the Gutenberg–Richter frequency-magnitude distribution indicates that, despite obvious spatiotemporal changes in seismicity characteristics during the crisis, there was no significant change of b with time. The high event rate provides a large statistical sample equivalent to a much longer catalog in terms of event numbers. This offers the chance to study the upper tail of the frequency-magnitude distribution in detail. While typical earthquake catalogs suffer from poor sampling in this domain, the Santorini crisis is suited for constraining the largest earthquakes. Assuming a truncated Gutenberg–Richter distribution and using well-established methods from frequentist statistics, like calculation of exact confidence intervals, we find that the maximum observed magnitude $$m=5.2$$ m = 5.2 is close to the estimated maximum possible magnitude. We conclude that with 95% confidence, no earthquake with magnitude $$m>5.35$$ m > 5.35 can be expected.