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 10 kilometres, struck at 4:43 am (1943 GMT Saturday), about 135 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.

A series of aftershocks followed the powerful quake, sparking a further panic among residents and deterring them from returning to their homes.

A more powerful aftershock, measuring 7.6 on the Richter scale, with its epicentre on land about 76 kilometres north-west of Manokwari, took place about two hours later but triggered no tsunami, said Fauzi, an BMG official in Jakarta said.

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.

An official at the BMG office in Manokwari, identifying himself only as Moses, said there were a number of homes and walls damaged but no reports of injuries.

"We have received reports of many homes were severely damaged after the quakes," Moses said in a telephone interview.

A reporter with the Jakarta-based Elshinta private radio said that a number of buildings, including Mutiara hotel in Manokwari were heavily damaged with many of its walls collapsed.

A number of collapsed and damaged homes also reported in Sorong district town, but no reports of casualties.

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)