MOSCOW, April 20 — The first tsunami wave — 40 cm (15.7 inches) in height — has reached the coast of the Iwate prefecture in Japan, according to the NHK broadcaster today, reported Sputnik/RIA Novosti.

It said the Japanese authorities are checking the operation of nuclear power plants after the powerful earthquake.

According to Tohoku Electric Power, Onagawa NPP in the Miyagi prefecture is being checked for possible deviations.

The operator of Tokyo Electric Power (Tepco) announced that the Fukushima-1 nuclear power plant in Fukushima Prefecture is being checked for possible new anomalies.

A similar check is being carried out at the Fukushima-2 nuclear power plant.

It added that Kyodo news agency reported that no emergencies were recorded at Fukushima-1 and Fukushima-2 nuclear power plants.

Earlier in the day, the Japanese Meteorological Agency said that a magnitude 7.5 earthquake occurred in the northern part of the Japanese island of Honshu in the Pacific Ocean in the area of Aomori and Iwate prefectures.

NHK reported that a tsunami was recorded at sea, approaching the Japanese prefectures of Iwate and Aomori.

The maximum force of the tremors was 5+ points on a seven-point scale adopted in Japan.

A tsunami threat was declared on the Pacific coast from the northernmost island of Hokkaido to the north of Honshu Island. It was also extended to the east coast of northern Japan. — Bernama-Sputnik/RIA Novosti