4.6 Magnitude Earthquake Near Katoizi, Greece; Cable Jonah Shows RTT Increase

Earthquake in Greece

On September 8, 2026, at 10:46 local time, an earthquake with a magnitude of 4.6 occurred 1 km north-northwest of Katoizi, Greece. This region is located in a seismically active zone where tectonic movements may affect submarine cables providing international internet traffic.

Submarine Cables in the Earthquake Zone

Within a radius of 500 km from the earthquake's epicenter, several submarine cables are situated. Among them:

• Jonah (2297 km, commissioned in 2012, operated by Bezeq International Ltd.), the nearest connection point is Bari, Italy, 479.7 km from the epicenter.
• Adria-1 (440 km, RFS 1996, ALBtelecom and Hrvatski Telekom), the nearest connection point is Corfu, Greece, 175.3 km away.
• Thetis (660 km, RFS 2022, Vodafone), the nearest connection point is Aethos, Greece, 175.6 km away.
• Italy-Greece 1 (IG-1) (169 km, RFS 1995, WIS Telecom), the nearest connection point is Aethos, Greece, 175.6 km away.
• EMC West-1 (3639 km, RFS 2027, EMC Subsea Cable Company Limited), the nearest connection point is Athens, Greece, 223.3 km away.
• MedNautilus Submarine System (7000 km, RFS 2001, Sparkle), the nearest connection point is Athens, Greece, 223.3 km away.
• Medusa Submarine Cable System (8760 km, RFS 2026, AFRIX Telecom), the nearest connection point is Athens, Greece, 223.3 km away.
• Thetis Express (340 km, RFS 2027, Vodafone), the nearest connection point is Athens, Greece, 223.3 km away.

Cable monitoring data

According to our measurements, the cable Jonah demonstrated a significant increase in round-trip time (RTT). Prior to the earthquake, the base RTT was 87.2 ms, but after the event, it increased to 119.0 ms, representing an increase of 31.8 ms (3.1σ above the baseline level). This may indicate temporary changes in routing or physical impact on the cable.

For other cables in the epicenter area, such as Adria-1, Thetis, and IG-1, no anomalies in delay or bandwidth metrics were recorded. Their infrastructure withstood the seismic impact due to structural features and distance from the epicenter.

Potential Risks for Traffic

The increase in RTT on cable Jonah may affect traffic routes between Israel and Europe, particularly through nodes in Italy. This could lead to temporary delays for users and services dependent on this trunk line. However, due to the availability of alternative routes such as MedNautilus and Medusa, global internet traffic in the region remains resilient.

Undersea cables in the Mediterranean Sea regularly face risks associated with seismic activity, highlighting the importance of their protection and monitoring.

FUTURE MONITORING

We will continue to monitor the condition of the Jonah cable to determine whether the increase in RTT is a temporary phenomenon or related to physical damage. Attention will also be paid to the Adria-1, Thetis, and IG-1 cables, despite their stable performance, to rule out any possible hidden consequences.

Information about the condition of the cables will be updated in real-time to provide timely information for operators and users.