Tokyo area's millions of residents urged to stay alert after strong quake

A powerful earthquake rocked the Kanto region early on Thursday morning, and authorities are warning the area's millions of residents that another could strike at any moment.

The magnitude-5.2 temblor occurred at 4:16 a.m., waking many people from their sleep.

Officials at Japan's Meteorological Agency say the focus was in southern Chiba Prefecture neighboring Tokyo at a depth of 40 kilometers. They say there was no threat of tsunami.

The quake measured upper 5 on Japan's seven-tier intensity scale in Kisarazu City. Jolts registering lower 5 were felt in Kimitsu City. Local authorities say three people were injured.

air shot with roof tiles fall off
Authorities are investigating the extent of the damage.

Officials warn of landslides, falling rocks

Meteorological Agency official Kamaya Noriko says people in quake-hit areas should stay alert for more seismic activity.

She says the risk of falling rocks and landslides has increased, especially in areas hit by strong tremors.

And she warns another quake as powerful as upper 5 could strike over the next week.

Japan's Meteorological Agency held a news conference shortly after 6 a.m. on Thursday.

Expert: Early quakes pose added risk

Earthquakes are common in Kanto because two oceanic plates subduct under another below the Japanese archipelago.

Meteorological Agency officials say Thursday's quake occurred on the Philippine Sea Plate.

The area around the epicenter has been rocked by large tremors before. They include a quake in May 2019, which had a magnitude of 5.1 and an intensity of lower 5.

Professor Satake Kenji of the University of Tokyo's Earthquake Research Institute says early morning jolts pose a particular set of risks.

"I believe many residents were asleep... I hope people don't get injured by falling objects after being woken by tremors."

Broken bottles are seen in a store after the quake.

For up-to-the-minute earthquake information in Japan, click here