For the first time, geologists have seen and documented a 7km deep tear in the sea floor north of Australia – one of the biggest fault-lines on Earth – and hope it could lead to a breakthrough in predicting earthquakes and tsunamis around the Pacific.
Researcher Jonathan Pownall from the Australian National University said the abyss, known as the Banda Detachment, has been known for 90 years but no one has been able to explain how it got so deep until now.
It lies on the Ring of Fire, the area where 90% of the world’s earthquakes and 81% of its worst earthquakes occur. The Ring extends from New Zealand, around the top of Australia and past Indonesia. It curls around past Japan and down the US west coast to the bottom of South America.
The Australian and Royal Holloway University of London researchers found the tear in the ocean floor has exposed over 60,000 sq km of the Earth’s crust.
“The discovery will help explain how one of the Earth’s deepest sea areas became so deep,” Pownall said.
“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.
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, a 6.9 magnitude earthquake shook the Japanese coast of Fukushima. A tsunami followed not long after.
On March 11, 2011, the most powerful earthquake ever recorded to hit Japan, and the fourth most powerful earthquake recorded since modern records began in 1900, also hit Fukushima. The magnitude 9 quake was followed by a tsunami with 40.5m waves; almost 16,000 people were killed, three nuclear power plants were destroyed, and hundreds of thousands of buildings crumbled in the costliest natural disaster in history.
Last week, more than 100 people were killed and 84,000 left homeless after an earthquake of magnitude 6.5 struck western Indonesia. The earthquake killed more than 100 people. It was the second major earthquake and tsunami in the area this year.
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, a magnitude 5.8 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 along the Ring of Fire was in the 1960s in Chile. At 9.5 magnitude, it’s the strongest earthquake on record.
HOW WAS THE TEAR FORMED?
Researchers have identified 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.
An Australian National University report said there was no evidence of recent earthquakes occurring over the tear, but researchers can’t rule it out.