South Korea’s weather agency said on Tuesday that a tsunami with a crest as high as 85 centimeters was observed off the country’s east coast following the powerful seven-point-six magnitude earthquake in Japan on Monday.

The tsunami was observed at 8:35 p.m. Monday at Mukho Port in Gangwon Province, exceeding the standard for a tsunami warning issuance with an undersea quake with a magnitude of six or more occurs and a tsunami at least 50 centimeters high is expected.

The Korea Meteorological Administration said while the height of the waves are decreasing, caution is needed along the coast for the time being.

It marks the first time in 31 years that a tsunami has struck the east coast of South Korea.