North Japan: Megaquake alert after 7.5 quake; tsunami risk for Pacific coast.

• Officials issued an alert for a potential megaquake in northern Japan following a 7.5 magnitude earthquake on December 8.
• A potential megaquake could trigger tsunamis along Japan's Pacific coast from Hokkaido to Chiba Prefecture.
• The initial 7.5 magnitude earthquake, recorded off Aomori Prefecture, caused six injuries and led to tsunami advisories and observations.
• Tohoku Shinkansen bullet train services were suspended between Morioka and Shin-Aomori stations due to the earthquake.
• The Japanese government established a task force and the Prime Minister instructed immediate information dissemination and damage assessment.

Why It Matters: Japan's megaquake alert signals serious tsunami risk for its Pacific coast.