All of Japan is prone to earthquakes. The latest one actually happened to the North, in a cooler area than Tokyo. That said, Tokyo isn't particularly hot for Japan. Sure Hokkaido and Tohoku are much cooler, but Tokyo is in the coolest half of Japan.
Ping is a lot more important than an eventual earthquake even in Japan. Especially considering that all of Japan is prone to earthquakes. If you go up North, the Kinki area (Osaka, Kobe, Kyoto) will be quite far away, and lines will have much less redundancy than in a highly populated area.
In short, making a decision based on a possible huge natural disaster in the Kanto area would be a massive knee-jerk reaction.
Ping is a lot more important than an eventual earthquake even in Japan. Especially considering that all of Japan is prone to earthquakes. If you go up North, the Kinki area (Osaka, Kobe, Kyoto) will be quite far away, and lines will have much less redundancy than in a highly populated area.
In short, making a decision based on a possible huge natural disaster in the Kanto area would be a massive knee-jerk reaction.