The Australian Government's Department of Foreign Affairs and Trade has issued a formal warning not to travel within 20KM of the Fukushima Nuclear Power Plant in Japan, or the Miyagi Prefecture.
Tokyo and surrounds, Chiba, Fukushima, Aomori, Iwate, Nagano, Niigata and Ibaraki prefectures, are categorised as "reconsider your need to travel".
The warnings are vital information if you are considering travelling to Japan, as travel insurance will almost certainly not cover you once "do not travel" government warnings are issued.
However, as was evident in the recent Queensland floods, travel insurers can also refuse claims for trips commenced after a person should have been "reasonably" aware that their travel destination was dangerous -- which would likely have been as soon as the Japanese tsunami occurred, soon after the earthquake.
If you are still considering a trip to Japan in the near future, be sure to get written advice from your travel insurer on how they will cover you in the case of a claim.
Some policies also specifically exclude coverage for natural disasters or acts of God.
It seems highly likely Australia will upgrade its travel alert soon to warn Australians off travelling to Japan at all. The US State Department has warned US citizens to avoid travelling to Japan altogether, and the UK Foreign and Commonwealth Office has advised only essential travel should be undertaken to north-eastern Japan.
Meanwhile, one airline has started scanning planes out of Japan for signs of radioactivity, and has pulled its flagship A380 off the route. However, Australian airlines Qantas and Jetstar say that is not necessary.
For travellers in Japan trying to get out, or for people who still need to get there for one reason or another, we've put together a guide on your best options for getting to/from Japan.
However, a large ash plume from a volcano erupting in Japan following the earthquake has been disrupting flights, so check with your airline whether there's impact to flight schedules.