Communications were slowed down in several countries that rely on undersea cables near Japan. Chunghwa Telecom stated that the undersea cable, Asia-Pacific Cable Network 2 (APCN 2), suffered damages because of the recent Japanese earthquake, disrupting communications for many countries in East Asia.
In Korea, many major websites either loaded slowly or went totally offline. Some of the sites affected by the quake were Facebook, Yahoo, and Google.
Google, in particular, was severely affected by the earthquake's damage, as the portal and its many services such as Gmail, Google Translate, Google News, Google Calendar, Youtube, and Blogger were offline for over 24 hours. The outage started on Saturday, March 12, and continued until Google was restored sometime on Sunday, March 13.
During the outage, those who tried pinging google.com [188.8.131.52] using the Command Prompt in Windows, got no response from the site, and had all their ping requests time out.
On their Apps Status Dashboard at 3:54 a.m. KST on March 11, Google stated, "We're experiencing an issue affecting less than 0.2% of the Google Mail user base. The affected users are unable to access Google Mail. We will provide an update by March 10, 2011 4:54:00 AM UTC+9 detailing when we expect to resolve the problem."
At 7:19 a.m., Google said that the problem "should have been resolved."
It could have been the case that those 0.2% users of Gmail were mostly those users located in Korea.
Google has since been restored back to near-full functionality, and all of its services are back online, at least for Korean users. This most likely means that the damaged undersea submarine communications cables have been repaired.
This isn't the first time Google has gone offline. Google and its many services went down on May 14, 2009. For several hours, Google suffered a worldwide breakdown because of an internal Google failure. To read Google's official explanation, see Google's official blog.
To check if a Google App is down or working, check Google's Apps Status Dashboard.