Japan's Meteorological Agency plans to begin using data from a new network of undersea seismic and tsunami observation system to detect offshore tsunami more quickly.

The system is part of efforts to brace for a mega quake that is expected to hit the Nankai Trough off the Pacific coasts of Japan.

The new network covers offshore areas off Cape Muroto in Kochi Prefecture in western Japan through Hyuganada which are the waters off the coast of Miyazaki Prefecture in southwestern Japan. There were no observation points in those areas.

The National Research Institute for Earth Science and Disaster Resilience has been working to install the observation network, called N-net, on the seabed off the Pacific coasts of Kochi through Miyazaki.

The institute has installed 18 observation nodes equipped with seismometers and tsunami gauges. They are half of the total observation nodes planned to be installed in the areas.

The quality of data obtained by the system has been verified in the experimental operation that began in July.

The meteorological agency is expected to begin using the data on November 21. The agency says the new network will help detect tsunami which occurs around the observation nodes up to 20 minutes faster.

The data is also expected to help the agency to issue tsunami alerts and raise or lower the levels of alerts faster.

The agency's quake and tsunami monitoring section says that people should evacuate promptly based on offshore tsunami information as tsunami waves tend to become higher as they approach the coastline.