Mount Raung on Java island blasted ash and debris up to 2,000 meters (6,560 feet) into the air after rumbling for several weeks, government volcanologist Surono said.
Ash erupted also from Gamalama and Dukono mountains on the Moluccas islands chain, Sinabung volcano on Sumatra island and Mount Karangetang on Siau island, darkening the skies, Surono said.
A total of more than 13,000 people have been evacuated due to the volcanic eruptions since last month, mostly from around the slopes of Sinabung in Tanah Karo District, added Surono, who uses a single name.
"Our evaluation showed there is no extraordinary natural phenomenon that triggered simultaneous eruptions of the five volcanoes," Surono said, adding that all the eruptions are natural and normal occurrences in a nation with about 130 active volcanoes.
Comment: Nothing to see here folks! It's just increasing climate chaos on the way towards sudden glacial rebound! Move along!
Comment: Other underwater volcanoes have been discovered in recent years from off the coast of New Zealand to Antarctica. In April this year, scientists were stunned by the apparent eruption of a submarine volcano, 'Axial Seamount' off the Northwest US coast (at a similar time to the devastating Nepalese earthquake and the massive eruption of the Calbuco volcano in Chile), which could explain the "unprecedented warming occurring over the last 13 years" of water in this area.
As the number of volcanoes erupting right now is greater than the 20th century's YEARLY average, a comparable escalation in activity of their underwater counterparts seems logical.
It is estimated there are up to one million submarine volcanoes on our planet. Effects from this volcanic activity, combined with increased methane outgassing, radiation from the Fukushima disaster are probably also causing the ongoing devastation of marine life, mass fish die offs and strange migratory behaviour we are currently witnessing.