Volcano's Ear: Fiber Optic Cable Listens for Eruption

An active underwater volcano near Santorini, Greece, has been transformed into a sensitive undersea "ear" using a fiber-optic cable. Scientists are now monitoring the Kolumbo volcano crater to detect signs of an impending eruption.

Kolumbo, located approximately 7 kilometers northeast of Santorini, last erupted in 1650, resulting in toxic gases and a tsunami that claimed dozens of lives. With Santorini attracting millions of visitors annually, the need for enhanced monitoring became critical after a swarm of over 30,000 earthquakes occurred nearby in early 2025.

The HYDROSENSE mission, a collaboration involving research institutions from Greece, the United States, and Italy, is lowering approximately 500 meters of cable into the crater at depths nearing 500 meters. This advanced technique, known as distributed acoustic sensing, uses laser pulses to convert the ordinary cable into hundreds of sensors capable of detecting faint tremors and seabed gas bubbling.

Researchers emphasize that this technology represents a significant scientific advancement, particularly for monitoring undersea environments where direct observation is challenging. The mission has deployed robotic submersibles to guide the cable into the volcano's steep crater. Following the mission's conclusion, the cable will be retrieved, prompting calls for sustained funding to establish a permanent observatory at Kolumbo.