Magnitude 5.1 Earthquake Near Guam Causes Anomaly on PPC-1 Submarine Cable

What Happened

On September 10, 2026 at 16:28:15 (UTC), an earthquake of magnitude 5.1 occurred 162 km southwest of Merizo, Guam. The epicenter was near key points of the regional submarine cable infrastructure, raising concerns about potential impacts on global internet traffic.

Cables in Zone

Within a radius of 500 km from the earthquake's epicenter, several submarine cables are located, including:

• PIPE Pacific Cable-1 (PPC-1): 6900 km, commissioned in 2009, operator Vocus Communications, exit point at Pitihisi, Guam (183 km from the epicenter).
• Echo: 17184 km, commissioned in 2025, operators Google and Meta, exit point at Agat, Guam (173.4 km from the epicenter).
• Apricot: 11972 km, commissioned in 2025, operators Chunghwa Telecom and Google, exit point at Agat, Guam (173.4 km from the epicenter).
• Atisa: 279 km, commissioned in 2017, operator Docomo Pacific, exit point at Pitihisi, Guam (183 km from the epicenter).
• Bulikula: 21600 km, planned commissioning in 2026, operator Google, exit point at Pitihisi, Guam (183 km from the epicenter).
• HANTRU1 Cable System: 2917 km, commissioned in 2010, operators FSMTCC and Hannon Armstrong, exit point at Pitihisi, Guam (183 km from the epicenter).
• Japan-Guam-Australia North (JGA-N): 2600 km, commissioned in 2020, operator Lightstorm Telecom, exit point at Pitihisi, Guam (183 km from the epicenter).
• Japan-Guam-Australia South (JGA-S): 7081 km, commissioned in 2020, operators AARNET and Google, exit point at Pitihisi, Guam (183 km from the epicenter).

What Our Measurements Show

Monitoring has detected anomalies on cable PPC-1. The round-trip time (RTT) of the signal increased from its baseline value of 217.3 ms to 261.5 ms, representing a jump of 44.3 ms (2.4σ above average). This indicates possible partial damage or temporary changes in the cable's characteristics.

On other cables, including Echo, Apricot, and JGA-N, the infrastructure has held up under load, and metrics remain within normal ranges.

Context and Risks

Guam is a crucial node in the global submarine cable network connecting Asia, Australia, and North America. Damage to any of the cables in the region could lead to traffic slowdowns and increased delays for users worldwide. This is particularly relevant for PPC-1, which connects Australia with Guam and further to Asia and the United States.

While the impact of the earthquake on the network as a whole was limited, the detected anomaly on PPC-1 requires additional attention to prevent further degradation in performance.

Further Monitoring

We will continue to monitor the condition of all cables in the earthquake zone, paying special attention to PPC-1. Data analysis will help determine whether the cable requires maintenance work or changes to traffic routes to minimize delays.

Monitoring will also be conducted for possible delayed effects on other cables, such as Echo and Apricot, to react promptly to any changes in their operation.