Insights from the Methana Magmatic Observational Experiment (MeMaX): Seismological Monitoring of Magmatic and Tectonic Activity in the Western Saronic Gulf Region, Greece

The South Aegean Volcanic Arc remains active, presenting not only primary volcanic hazards such as ashfall and lava flows but also secondary hazards from active submarine and coastal volcanoes with the potential to trigger tsunamis. These tsunamis pose a threat even to far-distant coastlines, as shown by the destructive history of large-scale eruptions in the Mediterranean, including the Thera/Santorini explosion (~1600 BCE). With growing population density, expanding infrastructure development, and seasonal tourism, both primary and secondary volcanic risks along the Aegean coasts are increasing, even with respect to smaller, more frequent eruptions.

This study focuses on the western Saronic Gulf region within the Aegean Sea, as possible impacts may even extend into the greater Athens metropolitan area. In this region, the dormant volcanoes of the Methana volcanic system, which last erupted in 230 BCE, and the submarine Pausanias Volcanic Field represent underappreciated hazards. To address this, we search for evidence of possibly yet undetected magmatic activity through the identification of related microseismic events.

Since 2019, the National Observatory of Athens and the University of Patras operate six seismic stations on Methana and the nearby Peloponnese mainland. In March 2024, an additional 15 seismic recording stations were deployed across Methana, Aegina, Agistri, Kyra, and Poros islands and the mainland Peloponnese for a two-year period.

This expanded network configuration provides a dense and robust azimuthal coverage of seismic ray paths for earthquake location and structural analysis. The continuous recordings enhance the observational capacities for earthquake detection, e.g. first results indicate low noise levels at the recording sites and that low magnitude events to ML ca. 0 can be recorded with very good signal-to-noise ratios. This geophysical experiment is part of the DAM mission ‘mareXtreme’ under the MULTI-MAREX project.