Two earthquakes shook northern Japan on Tuesday, triggering evacuations and tsunami warnings. The earthquake caused a small tsunami and has been traced back to the Great East Japan Earthquake from 2011.

The first earthquake struck in the early hours of Tuesday and was recorded to be 6.9 on the Richter scale, according to Reuters. Measured at a depth of 6 miles, the earthquake did not cause any casualties and did not affect any of the country's nuclear reactors.

According to The Guardian, the Japan Meteorological Agency issued a tsunami warning. Towns in the prefecture of Iwate near the coastline were evacuated as a precaution. NHK, a Japanese broadcaster, warned a meter-high wave could hit the Iwate coast. However, NHK later reported small 10-centimeter high waves some 45 minutes after the quake.

The second quake hit later on Tuesday and measured 5.7 on the Richter scale, but no tsunami warning was issued, reports Reuters. The earthquake originated some 30 miles under the surface and caused some small waves across the coastline.

Although earthquakes are a common occurrence in Japan, as the island nation lies on the Ring of Fire, these two quakes are remnants of the disastrous earthquake of 2011. According to the Wall Street Journal, Tuesday's earthquakes are aftershocks of the Great East Japan Earthquake, which registered 9.0 on the Richter scale. The earthquake struck in 2011 and leveled great parts of the Japanese coastline after it triggered a tsunami. The subsequent disaster left more than 15,000 people dead and more than 2,000 missing.

The Japan Meteorological Agency said later on Tuesday that the two quakes were aftershocks of the great earthquake. The 6.9 quake that struck first is the 830th aftershock with a magnitude of more than 5.

The Japan Times reports that Tohoku Electric Power Co. said Onagawa and Higashidori nuclear plants in nearby prefectures were not affected. All of Japan's 48 nuclear reactors have been offline since the 2011 quake.

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