A tear in the sea floor 7km deep just north of Australia could cause disastrous earthquakes and tsunamis.
The tear in the Earth's crust is in the Banda Sea, near Indonesia, and measures about 60,000sq km - roughly the size of Tasmania.
Geologists have now discovered the tear is one of the biggest faults on the planet and is running through the Ring of Fire, an area in the Pacific Ocean where a huge number of earthquakes and volcanic eruptions occur.
According to the United States Geological Survey, 90 per cent of the world's earthquakes and 81 per cent of the world's worst earthquakes occur along the Ring of Fire.
The ring extends from New Zealand, around the top of Australia and past Indonesia. It curls around Japan and down the West Coast of the United States before ending at the bottom of South America.
Just last month it became even more evident how dangerous the Ring of Fire could be.
On November 14 Kaikoura was struck by a magnitude 7.9 earthquake that casued widespread damage and killed two people.
On November 22, an earthquake with a magnitude of 6.9 shook the Japanese coast of Fukushima prefecture and tsunami waves followed not long after.
This month, 84,000 people were left homeless after an 6.5 magnitude earthquake struck western Indonesia. The earthquake killed more than 100 people.
A huge undersea earthquake in 2004 triggered a tsunami that engulfed several countries around the Indian Ocean, killing more than 170,000 people in Indonesia alone, the vast majority in Aceh, on the northwest tip of Sumatra Island.
In August this year, a 5.8 magnitude earthquake hit off Queensland's east coast near Bowen.
It was believed to be Queensland's biggest quake in 20 years.
The most catastrophic earthquake on the Ring of Fire was in the 1960s in Chile.
It's the strongest earthquake on record and had a magnitude of 9.5.
According to University of Technology Sydney's Geotechnical and Earthquake Engineering senior lecturer Behzad Fetahi, the borders of tectonic plates meet in the Ring of Fire.
"They move away from each other and push each other, it's one of those very active areas," he said.
The tear could cause more catastrophic earthquakes and tsunamis, not only because it's on the Ring of Fire, but because earthquakes around the deep tear could cause it to slip, causing more violent tremors on surrounding islands.
A sudden slip on the tear will release energy in waves, creating violent shaking on Earth.
For decades there have been questions about how the tear, near Indonesia, was formed.
"The hole has been known for 90 years but until now no one has been able to explain how it got so deep," Australian National University lead researcher Jonathan Pownall said.
How was the tear formed?
Researchers say the deep hole, known as the Banda Detachment, was created by subduction, where one tectonic plate moves under another and is forced downwards, sinking through the Earth's crust into the mantle.
Pownall hopes this discovery will help people to assess the dangers of future tsunamis and earthquakes.
"In a region of extreme tsunami risk, knowledge of major faults such as the Banda Detachment, which could make big earthquakes when they slip, is fundamental to being able to properly assess tectonic hazards," he said.
An Australian National University report on the deep hole said there was no evidence of recent earthquakes over the tear, but researchers can't rule it out.
The area around the tear is prone to frequent earthquakes and volcanic eruptions and the Ring of Fire is the most seismically active zone on the planet.
- with AAP