A powerful 7.5 magnitude earthquake struck off Japan's northern coast, prompting tsunami warnings and widespread disruption.The tremor caused minor injuries to at least 34 people, forced 90,000 residents to evacuate, and led to the temporary suspension of Shinkansen bullet train services.Prime Minister Sanae Takaichi formed an emergency task force to assess the damage, while the Japan Meteorological Agency warned of potential stronger aftershocks and a future megaquake risk for the next week.