A Living Laboratory for Improved Forecasting and Action Options for Multiple Geomarine Extreme Events, Cruise No. M215, Dec. 17, 2025 - Jan. 10, 2026, Heraklion (Greece) - Limassol (Cyprus)

Cruise MMC-3 forms part of the collaborative project MULTI-MAREX within the DAM mission mareXtreme. It investigated multi-source and cascading geomarine hazards in the Santorini–Kolumbo–Amorgos region, where seismogenic faulting, magma transport, and slope instabilities are mechanically coupled. The cruise targeted hazard indicators and triggering mechanisms using complementary seismological, geodetic, electromagnetic, and high-resolution mapping approaches. A primary objective was to advance monitoring concepts toward operational readiness through the continued deployment and evaluation of seafloor sensor networks. Five ocean-bottom seismometers (OBS) were installed between Santorini and Amorgos to improve earthquake and long-period event localization, while pressure and temperature sensors were deployed on the Santorini caldera floor to resolve vertical deformation and fluid migration. Temporary MOLA networks equipped with geophones, hydrophones, and acoustic telemetry were tested, including communication via a gateway buoy and an unmanned surface vehicle (Blue Boat). Subsurface fluid distributions were targeted through a three-week magnetotelluric survey across the Anhydros Block, above a shallow dike intrusion. Hydrothermal and morphologic change detection was addressed through repeated MOMO-based photogrammetry at Kolumbo and within the Santorini caldera (Nea Kallisti/Kallisti Pools; Kameni lava flows), complemented by multibeam and AUV micro-bathymetry of Kolumbo and the western Amorgos fault zone. Outreach and stakeholder engagement accompanied operations within the Santorini Living Laboratory to support hazard preparedness and response capacity.