Japan issues first-ever alert over possible Nankai Trough megaquake following 7.1-magnitude quake

Tokyo, Aug 8 : A 7.1-magnitude earthquake struck Miyazaki prefecture and other areas in southwestern Japan on Thursday, prompting the country's weather agency to issue its Nankai Trough Earthquake Extra Information for the first time.

The earthquake, measuring lower 6 on the Japanese seismic intensity scale of 7, occurred at 16:43 local time at a depth of 30 kilometers off the waters of Hyuga-nada in southern Kyushu, one of the country's four main islands, according to the Japan Meteorological Agency (JMA).

Shortly afterwards, the JMA started investigating whether this earthquake is related to the possibility of a large-scale quake anticipated along the Nankai Trough, which experts have warned for years, and could cause huge loss of life and property across a wide swathe of central and western Japan.

On Thursday evening, the JMA issued an alert warning about a possible massive earthquake around the Nankai Trough, the first such alert. A panel of experts assessing the matter said the probability of a major earthquake along the Nankai Trough has increased "several times," calling for people to be prepared for any eventuality.

Following the afternoon quake, tsunami advisories were issued for Miyazaki, Kochi, Ehime, Oita, Kagoshima prefectures on the islands of Kyushu and Shikoku, but the JMA lifted them except for Miyazaki, Xinhua news agency reported.

Small waves have already been recorded in some areas. Tsunami with heights of around 50 centimeters and 20 centimeters was observed in Miyazaki and southwestern Kochi, respectively, the JMA said.

Several injuries have been reported in Miyazaki and other prefectures in Kyushu, Kyodo News reported.

There have been no reports of abnormalities at Ikata and Sendai nuclear power plants in Ehime and Kagoshima prefectures following the quake, and the government was checking for damage and casualties, Chief Cabinet Secretary Yoshimasa Hayashi said at a news conference.

Weather officials urged residents to take extra precautions against the danger of collapsed houses and landslides, as well as against aftershocks and rainfall.

The JMA, which initially estimated the quake's magnitude at 6.9, warned that quakes with a seismic intensity of around lower 6 could happen for the next week, especially over the next two or three days.