Today's 8.9 magnitude earthquake in Japan has had surprisingly limited impacts on the structure and routing dynamics of the regional Internet. Of roughly 6,000 Japanese network prefixes in the global routing table, only about 100 were temporarily withdrawn from service — and that number has actually decreased in the hours since the event. Other carriers around the region have reported congestion and drops in traffic due to follow-on effects of the quake, but most websites are up and operational, and the Internet is available to support critical communications.
Those who have been following our blogs on Libya will be familiar with the excellent Google Transparency Report, which summarizes the rate of queries coming from each country over time. Despite terrible fires, floods, and power outages, traffic from Japanese clients just keeps going. It's quite a remarkable plot.
Why have we not seen more impact on international Internet traffic from this incredibly devastating quake? We don't know yet, but we'll keep studying the situation. Compared to the 2006 Taiwan earthquake, which resulted in a larger number of major cable breaks, it appears that the majority of the region's submarine cables have escaped the worst damage, and diverse capacity remains to carry traffic around the points of damage.
In- and out-bound traffic at the Japan Internet Exchange dropped by some 25 gigabits per second after the quake .. and then climbed back to robust levels by the end of the day.
Traffic at the JPNAP also seems to be down by only about 10% over its historical rates from the last two weeks.
The primary effects seen during the hours after the quake seem to have been related to breaks in 2 segments of Pacnet's EAC cable system. The plot at right shows prompt increases in unreachable networks in Japan and the Philippines, with follow-on events several hours later in Hong Kong and the Philippines. Various Philippine companies (BellTel, Eastern Telecoms, and Bayan) experienced outages that correlated in time with the initial Japan and subsequent Hong Kong events, suggesting common routing on the affected cable. But again, it's important to note that these are very small numbers of affected networks, relative to the total Internet presence of these countries.
Since the initial event, the Pacific Crossing system has also gone down. Based on experience from the Taiwan quake, it's possible that lingering damage to fibers, repeaters, and landing station equipment may continue to generate new problems over the coming days and weeks, even in cable systems that survived the initial event.
Still, it's clear that Internet connectivity has survived this event better than anyone would have expected. The engineers who built Japan's Internet created a dense web of domestic and international connectivity that is among the richest and most diverse on earth, as befits a critical gateway for global connectivity in and out of East Asia. At this point, it looks like their work may have allowed the Internet to do what it does best: route around catastrophic damage and keep the packets flowing, despite terrible chaos and uncertainty.
[Saturday 23:30 UTC] Added JPNAP traffic graph per comments. Thanks!