Japan issues megaquake advisory for north after 7.5 quake, urges preparedness.

• Japan issued a megaquake advisory after a magnitude 7.5 earthquake off Aomori, warning of a potential larger quake.
• The advisory is a preparedness measure, not a prediction, with a 1% chance of a magnitude 8 or larger quake within a week.
• It covers 182 municipalities from Hokkaido to Chiba, urging residents to prepare for a possible 30-meter tsunami and significant damage.
• The warning is linked to the Japan and Chishima Trenches, similar to the 2011 disaster, and aims to prevent panic seen with a previous Nankai Trough advisory.
• Officials advise residents to have emergency bags, evacuation plans, and secure furniture to mitigate potential risks.

Why It Matters: Japan's megaquake advisory highlights urgent need for disaster preparedness.