Japan on high alert for 'huge' second quake after issuing tsunami warning

"As soon as we heard the earthquake alert, everyone ran downstairs," Chaw Su Thwe, a Myanmar national living in Hokkaido, told the BBC. "However, this time the shaking was relatively mild."Right now, local authorities are using loudspeakers in the neighbourhood to warn people about a possible tsunami and to stay alert," she added. "Office workers have been allowed to leave work early."A number of bullet trains were affected, and 100 homes were without power, Japan's Cabinet Secretary Minoru Kihara told reporters. He said there were no immediate reports of major damage or injuries.A tsunami warning was issued across part of Japan's east coast. The warning is the second-highest of three levels of alert, with people being told to evacuate immediately from coastal regions and riverside areas and move to higher ground or an evacuation building."Tsunami waves are expected to hit repeatedly. Do not leave safe ground until the warning is lifted," Japan's Meteorological Agency (JMA) told reporters in the hours after the quake - a plea echoed by Prime Minister Sanae Takaichi, who urged people to get to "higher, safer places".It was later downgraded to a tsunami alert, before being removed entirely shortly before midnight local time.Japan's precarious location on the Ring of Fire means it experiences about 1,500 earthquakes a year, and accounts for 10% of quakes measuring 6.0 magnitude or higher worldwide.