Maruyama: Global Cable Hub at Japan’s Pacific Coast

Where This Is and Why Cables Are Routed Here

The coordinates 35°N / 140°E mark the waters off Japan's Pacific coast, roughly opposite Chiba Prefecture and the entrance to Tokyo Bay. There is no narrow strait here in the classic sense: Maruyama is not a physical bottleneck but a functional one. The reason for the cable concentration is straightforward: Japan lies at the intersection of two major traffic axes: the Trans-Pacific (USA to Asia) and the Asian Arc (Southeast Asia to Northeast Asia). The shortest routes from North America to Asia skirt the Aleutian Arc and land precisely at Japan's Pacific coast. Laying cables across the open ocean farther west to Korea or China without an intermediate stop in Japan is neither technically nor economically viable. Additionally, Japanese operators-NTT, KDDI, SoftBank-have historically been co-investors in most trans-Pacific consortiums. The result: 25 cables converge in a relatively compact area.

What Passes Through Here

The list of main routes is impressive in scale. The longest is EAC-C2C (36,500 km), forming a loop from Japan to Australia via Southeast Asia. Following it is FLAG Europe-Asia / FEA (28,000 km), one of the oldest active Europe-to-Asia routes. Tata TGN-Pacific (22,300 km) and APCN-2 (19,000 km) round out the upper tier in terms of length. Among next-generation trans-Pacific systems passing through here are JUPITER (14,557 km), involving Facebook and Amazon, FASTER (11,629 km), a consortium of Google and Japanese operators, and New Cross Pacific / NCP (13,618 km). Regional Asian systems include SJC2 (10,500 km), Asia Pacific Gateway / APG (10,400 km), and Asia Direct Cable / ADC (9,988 km). Special mention goes to Unity/EAC-Pacific (9,620 km) and FLAG North Asia Loop/REACH North Asia Loop (9,504 km). The total length of the systems listed exceeds 270,000 km, meaning the Maruyama zone serves as a touchpoint for several percent of the planet's active submarine cable infrastructure.

Who Would Be Cut Off

If multiple cables in this zone were simultaneously damaged, 14 jurisdictions would immediately experience degradation. Direct traffic losses would affect:

• The USA and Guam: via trans-Pacific systems JUPITER, FASTER, TPE, NCP, Unity;
• Australia: Australia-Japan Cable / AJC (12,700 km) and EAC-C2C, with no alternative route northward;
• Taiwan, South Korea, and the Philippines: primarily through APG, ADC, SJC2, and APCN-2;
• China: despite having its own alternative routes via PEACE Cable and continental transit, a significant portion of international traffic transits through Japanese landing stations;
• Singapore, Malaysia, Thailand, Vietnam, and Brunei: via regional systems that connect to Japan as a key node.

Egypt appears on the list indirectly: FEA passes through the Suez Canal, and any disruption at the Japanese end impacts the throughput of this Europe-to-Asia route.

Real Risks in the Zone

Japan's Pacific coast is one of the most seismically active areas on the planet. The Nankai subduction zone and the Japan Trench create a constant background threat of underwater landslides that can physically displace or sever cables. The 2011 incident (the Tohoku earthquake, magnitude 9.0) caused damage to several systems in a zone similar to Maruyama-this is not hypothetical but a documented precedent. Vessel traffic in this area is extremely high: Tokyo Bay is one of the busiest port corridors globally, and anchor damage to cables in Japan's coastal zones occurs regularly. Fishing is another factor: Japanese and Chinese trawlers actively operate in these depths, and bottom trawling on the continental shelf reaches cable routes. Geopolitical considerations also play a role: the concentration of American and Asian commercial cables in one point makes it a theoretically attractive target during escalations in the Taiwan Strait or the Korean Peninsula-even without direct physical impact, the mere threat alters insurance and operational decisions for operators.

What GeoCables Monitors

In the Maruyama zone, GeoCables monitors all 25 cable systems in real time. Special attention is given to delays on the USA-to-Japan and Australia-to-Japan routes as early indicators of degradation: an RTT increase of 15-20 ms above the baseline on trans-Pacific routes signals congestion or partial failure even before official operator notifications. The vessel map in the zone is updated every 6 hours: cable-laying ships (such as Nexans Skagerrak or CS-class vessels) and ships anchored unusually long over known routes are tracked. When multiple signals coincide-delay increases, a vessel over a route, and a seismic event-the system automatically generates an alert for the zone.