An earthquake with a magnitude of 4.2 struck northern Hokkaido early Thursday and measured lower 5 on the Japanese seismic intensity scale of 7, Japan's weather agency said.
The focus of the quake, which occurred at around 1:09 a.m., was about 7 kilometers underground in the northern Soya region of Japan's northernmost main island, the Japan Meteorological Agency said. The agency did not issue a tsunami warning.
The agency later revised downward the magnitude of the quake from 4.4 to 4.2.
The temblor registered lower 5 intensity in the town of Toyotomi and 4 in the town of Horobetsu, the agency said. The weather agency defines lower 5 as an intensity at which many people are frightened and feel the need to hold onto something stable.
There were no immediate reports of injuries or property damage from the quake.
Nonetheless, the latest shaking has increased the risk of falling rocks and landslides should another quake of similar intensity hit soon, a weather agency official said at a press conference in Tokyo, urging people in the northern region to be on alert for around the next week.
Following the quake, Hokkaido's government launched a task force headed by Gov. Naomichi Suzuki to deal with the situation.
A male official of Horobetsu in his 40s told Kyodo News, "I felt a strong shake while sleeping at my home." He added that the town government is gathering information on possible damage from the quake.