A powerful earthquake measuring 6.2 on the northern island of Hokkaido struck early Monday morning in Japan. The Japan Meteorological Agency (JMA) said the quake struck at 5:23 a.m. local time, centered in southern Hokkaido. It was about 83 kilometers deep, down from an initial estimate of 6.1. The JMA warned residents to be vigilant, saying there was a high possibility of more earthquakes of similar magnitude in the coming days and weeks. A 5.0-magnitude earthquake struck just hours earlier, a few hundred kilometers south of Hokkaido, signaling that the region's seismic activity is continuing to increase. The quake followed a 7.7-magnitude quake in northern Iwate Prefecture last week that caused little damage but sent shockwaves across the country.

The quake's impact was felt as far as the capital Tokyo, where large buildings shook and six people were injured.

 In addition, tsunami waves of up to 80 centimeters high were seen in the Iwate region, while smaller waves hit other northern areas. 

The JMA then warned of the risk of a powerful earthquake of 8.0 or higher. The current 6.2-magnitude quake is also considered part of the same series.

Japan lies on the Pacific Ocean's 'Ring of Fire'. The country, which sits at the junction of four major tectonic plates, is hit by about 1,500 earthquakes each year. This is about 18 percent of the world's total.