The tsunami that devastated Indonesia on Saturday, killing more than 280 people and leaving thousands more injured, was caused by the eruption of a nearby volcano – a fact experts say helps explain why it struck the country without warning.

Experts believe that part of the wall of the Anak Krakatau volcano, which has been erupting sporadically since June, collapsed during an eruption on Saturday, triggering an underwater landslide that spawned the tsunami.

This makes it different from most tsunamis, including the 2004 Boxing Day tsunami that killed nearly 250,000 people in Indonesia and several other countries, which are triggered by seismic activity that often results in some sort of warning.

“In this case, there was no earthquake as such,†Simon Boxall, an oceanographer at the University of Southampton, told Â鶹´«Ã½ Channel. “And so there wasn’t even the chance for people to realize an earthquake would lead to a tsunami, so there was very little that could have been done in this case.â€

But the fact that the tsunami was triggered by a volcanic eruption and not an earthquake does not fully account for the tsunami’s devastation.

Rob Marciano, a meteorologist with ABC News, said that the speed of a tsunami, which can travel up to 800 kilometres per hour, coupled with the volcano’s proximity to major cities such as Jakarta and Sumatra, also help explain why the tsunami was so deadly. This tsunami also occurred at high tide during the full moon, which made its impact worse.

“Even with a warning system,†he said, “it would take less than 10 minutes to get where it is.â€

Indonesia’s geography makes it prone to earthquakes and tsunamis, experts say. The country sits on the Ring of Fire, which is home to nearly 450 volcanoes and where most major earthquakes occur.

Anak Krakatau was formed after the 1883 eruption of the volcanic island of Krakatoa, which killed more than 30,000 people and spewed so much ash that global temperatures dropped.

Boxall said that because the Indian Ocean is so vast, thousands of monitoring systems are needed to cover the area. Many of the sensors currently in place were installed after the Boxing Day tsunami in 2004 and a number of them are not working.

“We can’t stop it from happening again,†David Rothery, a geosciences professor at the Open University in Northamptonshire, England, told CTV National News.

“The island is going to continue to grow volcanically and there will be a risk of future tsunamis.â€

The tsunami will require an international response, Boxwall said, that includes medical supplies and shelter.

“These tsunamis don’t just cause loss of life,†he said. “They cause loss of habitat.â€