After a 7.5-magnitude earthquake on Monday, Japanese officials issued a rare warning for a potentially even larger follow-up.

Osaka Metro Co. conducted a disaster drill early Saturday at a train station in the major western Japan city it serves to prepare for

Japan has been struck by another strong earthquake — a 6.9-magnitude tremor hitting the same Pacific coastal region shaken by Monday’s 7.5 mega-quake. The new quake triggered a tsunami advisory, warning of 1-meter waves across Hokkaido,

"Please stay prepared to evacuate immediately if you feel any shaking, while continuing your socioeconomic activities.”

Japan is warning about a potential megaquake after a massive earthquake struck parts of the country. CBS News' Errol Barnett reports.

Japan’s government has issued a rare “megaquake advisory” after a 7.5 magnitude earthquake struck off the country’s northern coast on Tuesday, warning that a much larger offshore quake could generate a towering tsunami in the coming days.

Japan ’s weather agency has issued its highest-level warning that a megaquake could follow Monday’s 7.5-magnitude tremor. Authorities urged anyone living near the Pacific coast to remain vigilant throughout the coming week and to prepare evacuation plans in case they need to flee their homes.

A powerful 7.5-magnitude earthquake sent shockwaves through Hokkaido and Tohoku, plunging Japan into a night of chaos, freezing evacuations and viral footage that captured the raw force of the tremor.