Tsunami warnings issued but lifted by Tuesday morning Authorities warn of heightened possibility of mega-quake for 1 week No irregularities at nuclear plants, power supply resumes after some outages 30 injuries reported so far, prime minister says Yen weakens against major currencies TOKYO, Dec 9 (Reuters) - Japanese authorities lifted tsunami warnings on Tuesday hours after a powerful 7.5-magnitude earthquake shook northeastern regions, injuring at least 30 people and forcing about 90,000 residents to evacuate their homes.

The Japan Meteorological Agency said the magnitude 7.5 quake - downgraded from its first reading of 7.6 - raised the chances of similar or larger tremors in the coming days.