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Following the 11 March earthquake in Japan, the national telecoms network appears to have fared well.

Despite a burst of traffic after the quake as customers attempted to contact friends and family, traffic management was able to prevent disruption to emergency communications, causing some congestion for ordinary customers. Several submarine cables were damaged, but Japan's international infrastructure is highly diverse, and service disruption was manageable.

 

Japan's major telcos have been able to restore some fixed and mobile services in the worst affected areas, but the remaining problems will be harder to fix. We expect that some new problems will emerge in the coming weeks as stressed or damaged infrastructure fails, both on land and undersea.

 

Power shortages have led to rolling blackouts across the country, and these have disrupted access to fixed broadband and VoIP as terminal devices have been left without power.

 

Earthquakes damage telecommunications infrastructure in several ways. The vibrations from the quake, apart from shaking electronic equipment and civil infrastructure, can cause soil to liquefy, stressing or breaking pits, ducts, and cables. Liquefied soil can also enter pits and ducts.

 

Residual shearing, compression, and tension stresses in surrounding rock and soil also damage infrastructure, which can result in failure days or weeks after the initial earthquake.

 

Damaged ducts and pits can allow water to enter the system, which causes other failures, and undersea cables are particularly vulnerable to this threat. As a result, it is highly likely that further failures will occur. 

The two key infrastructure failures were the loss of fixed backhaul routes servicing fixed and mobile communications in the earthquake affected area, and losses of power as generator fuel and battery backups were depleted. On 14 March, the Japan Times quoted NTT East, the main service provider in northeastern Japan, which stated that 880,000 fixed lines were out of service in the region.

It also quoted the Internal Affairs and Communications Ministry, which stated that 11,400 mobile base stations were inoperative. Nationally, the majority of infrastructure remained functional, and data centers seem to have been largely unaffected.

 

While there was some disruption to international communications due to several reported cable breaks, international connectivity was surprisingly robust, particularly in comparison to the Taiwan earthquake of 2006, which severely disrupted communications in that country.

Since the earthquake, significant progress has been made towards repairing the damage. While fixed service disruptions are still a problem, service is gradually being restored. NTT DoCoMo, which reported that 6,720 of its mobile base stations were inoperative on March 12, announced that only 2,130 were still inoperative on March 15.