SYDNEY, Nov 22 (Reuters) - Authorities in the Solomon Islands said no tsunami warning would be issued after two powerful earthquakes struck on Tuesday, damaging Australia's embassy, the airport and shopping malls and triggering power cuts in the capital, Honiara.The first quake hit offshore at a depth of 15 km (9 miles), about 16 km southwest of the area of Malango, said the United States Geological Survey which initially put its magnitude at 7.3 before revising it down to magnitude 7.0."There are no known injuries but the roof of the High Commission annex has collapsed, which would point to likely damage throughout the city," Australian Prime Minister Anthony Albanese told parliament.Honiara International Airport suffered damage to its ceiling but the building was intact, a Solomon Islands Airline worker at the airport told Reuters by phone.Airport staff would continue working but the damaged section of the airport terminal was closed to passengers."