The U.S. Geological Survey says a powerful earthquake with a preliminary magnitude of 6.4 struck off Mentawai islands in western Indonesia.

There were no immediate reports of damage or casualties from the quake that was centered 195 kilometers (121 miles) west-northwest of Bengkulu on Sumatra island, at a depth of 23 kilometers (14 miles).

Indonesia is prone to seismic upheavals due to its location on the Pacific “Ring of Fire,” an arc of volcanoes and fault lines encircling the Pacific Basin.

Saturday’s quake happened four days after a magnitude-6.1 tremor killed at least 35 people and damaged more than 4,300 houses and buildings in Aceh province.

A magnitude-9.1 earthquake off Aceh in 2004 triggered a tsunami, killing 230,000 people in 14 countries.

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