Jakarta  - A powerful 7.2-magnitude quake struck at sea early Sunday off Indonesia's West Papua province, sending residents running out of their homes and other buildings, seismologists and authorities said.

A tsunami alert was issued by the Indonesian Meteorology and Geophysics Agency (BMG) but was later canceled after no waves materialized.

The quake, which hit at a shallow depth of 35 kilometres, struck at 4:43 am (1943 GMT Saturday), about 150 kilometres north-west of Manokwari, the provincial capital of West Papua, the BMG said.

The US Geological Survey put the quake at 7.6 on the Richter scale.

Thousands of residents including children and the elderly could be seen thronging the roads of the blacked-out Manokwari town, and they remained outdoors even after the tsunami warning was lifted, local police officials said.

A series of aftershocks followed the powerful quake, with the strongest measuring 6.1 on the Richter scale, sparking a further panic among residents and deterring them from returning to their homes.

There were no immediate reports of heavy damage or injuries.

Indonesia, the world's largest archipelago, sits on the Pacific "Ring of Fire," the edge of a tectonic plate prone to seismic upheaval.

A major earthquake and subsequent tsunami struck in December 2004, leaving more than 170,000 people dead or missing in Indonesia's Aceh province and around
500,000 homeless. (dpa)