Japanese Prime Minister Kishida Fumio has urged people to act to save their own lives in a mock news conference held as part of a national disaster drill.

Thursday's government-hosted disaster drill was based on the scenario that a magnitude 9.1 earthquake had occurred in waters to the south of Wakayama Prefecture at 7:10 a.m.

The quake triggered tremors registering 7 and upper 6 on Japan's seismic scale of 0 to 7 in many regions of the country, and a warning of major tsunami.

In a mock news conference at 9 a.m., Kishida said multiple buildings had been destroyed, mainly along the Pacific coast, and large-scale fires and flooding from tsunami had been confirmed.

He declared a state of disaster emergency, and said he would head an emergency task force that he set up.

Kishida added he would send a survey team to the site, and would work closely with local governments to restore essential utilities, provide supplies and medical care and run shelters where survivors can maintain social distancing.

The prime minister urged people to be mindful of information on earthquakes and evacuation, and to stay in a safe place.

He asked them to remain calm and refrain from overstocking food and other supplies to minimize confusion.