Manila: Three major earthquakes that occurred in the south Philippines on July 24 were due to the eruption of Kawio Barat, a big underwater volcano rising 10,000 feet from 18,000 feet of water between Indonesia and the south Philippines, said an expert, whose analysis was challenged by a local scientist.

Three major undersea earthquakes with magnitudes of 6.8 and 7.1 on the Richter scale, occurred in the Moro Gulf off Mindanao on July 24, the Philippine Institute of Volcanology and Seismology (Phivolcs) confirmed, adding the undersea quakes did not damage land areas.

The quakes, tectonic in origin, had nothing to do with the eruption of a recently discovered undersea volcano, the Kawio Barat, Mahar Lagmay, associate professor at the University of the Philippines National Institute of Geological Sciences, told the Inquirer.

However, Jim Holden, chief scientist for the US-Indonesia deep-sea expedition of Kawio Barat, said in a press release quoted by the Inquirer that the major earthquakes off south Philippines last month were due to the eruption of Kawio Barat, which was recently found by scientists under the seabed of Sulawesi Islands in Indonesia.

On June 30 this year, Okeanos Explorer, a vessel with remotely operated vehicle (ROV) and sophisticated multi-beam sonar technology for mapping the seabed held a second dive for the Kawio Barat volcano.

The vessel showed images of "sulphide chimney emitting hot water among a field of chimneys and barnacles as far as the eye could see", according to the US-Indonesian ocean exploration team, whose expedition will end this month.

The Sulawesi Islands are 500 kilometres from Sarangani province in the south Philippines.

Cotabato trench

In 1976, a movement of the Cotabato Trench [in the south Philippines], resulted in an earthquake of 7.8 magnitude and a tsunami killing 8,000 people in Mindanao.

The Cotabato trench is in the vicinity of Kawio Barat, scientists said.

In 1883, Krakatoa's eruption between Java and Sumatra resulted in a tsunami that killed 60,000 people in coastal areas.

The Philippines is part of the Pacific Ring of Fire, a 40,000km area from Indonesia to Chile where earthquakes and volcanic eruptions occasionally occur.