A survey by a Japanese convenience store industry group shows that in the event of a mega quake, it would be difficult for them to resume operation for about a week in some areas.

The Japan Franchise Association conducted the study with the central and local governments.

The survey looked into possible impacts on convenience stores and their logistics networks if a mega quake takes place at the Nankai Trough, off Japan's Pacific coast or beneath the Tokyo metropolis.

In the case of a Nankai Trough earthquake, the survey shows up to 30 percent of convenience stores will not be able to operate in badly hit areas due to power outages and road closures.

It says people will likely have to wait about a week for stores to resume operation.

The research assesses that in the case a mega quake hits the greater Tokyo, many stores in areas without power will not be able to operate and face difficulty in resuming operation even a week after the quake.

The survey points out that the impacts could be prolonged, depending on the extent of road impairments, as well as tsunami related devastation.

The convenience store operators plan to call on their customers to make it a habit in their daily life to buy spare water, food and other stockpiles to prepare for disasters.