Magnitude 6.6 quake strikes off coast of Indonesia's Sumatra -GFZ

(Refiles to correct spelling in headline)

(Reuters) - An earthquake of magnitude 6.6 struck off the northwest coast of Indonesia's Sumatra island on Friday, the GFZ German Research Center for Geosciences (GFZ) said.

The quake was at a depth of 10 km (6.21 miles), GFZ said.

Indonesia's weather and geophysics agency, BMKG, put the quake at 7.2 magnitude and at a depth of 19 km but said it had no potential to trigger a tsunami wave.

On Dec. 26, 2004, a 9.1 magnitude quake off the coast of northwest Sumatra triggered a tsunami that killed more than 230,000 people in Indonesia, Sri Lanka, India, Thailand and nine other countries.

A Twitter user, Siska Sasmita, said Friday's quake was felt strongly in Padang city on Sumatra's west coast.

"We ran outside the house because the quake was felt for a pretty long time," said Goris Tukan, a resident of Nias island, off Sumatra. He said no damage were seen in his neighbourhood.

Disaster mitigation agency official Filifo Daili said the quake was felt for 20 seconds and authorities were still collecting information about its impact.

(Reporting by Bhargav Acharya in Bengaluru, Fransiska Nangoy, Agustinus Beo Da Costa and Bernadette Christina Munthe in Jakarta; Editing by Christopher Cushing)