They are often very expensive, and most will not take foreign customers. However, it can be very expensive. There are some cheaper ones. Rely on a good guide or a friend. The Japanese post office has a good service guide in English.
Earthquakes do happen in Tokyo.
Mostly, they are minor. Gas meters in apartments and houses have a sensor that turns off the gas during moderate tremors. If you have gas, make sure someone explains to you how to reset the meter. Tokyo Gas has a good instruction booklet in English. They are listed in Tokyo Journal.