A powerful earthquake has struck off the coast of Indonesia, followed by several aftershocks, the European-Mediterranean Seismological Centre says, triggering an early tsunami warning by the country's geophysics agency.The EMSC recorded a quake of magnitude 7.7 around 4.58am local time at a depth of 35 km.A series of seven aftershocks ranging from 5.0 to 6.1 in magnitude struck since, USGS reports.A 7.7 magnitude earthquake and seven aftershocks.Supplied / USGSIndonesia's geophysics agency BMKG issued an early tsunami warning for some regions in the country.Separately, Australia's tsunami warning centre said the undersea earthquake will have "no tsunami threat to the Australian mainland, islands or territories".- Reuters / RNZ