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Swift
2016-Nov-29, 04:20 PM
From R&D magazine (http://www.rdmag.com/article/2016/11/biggest-fault-earth-uncovered?et_cid=5701621&et_rid=54636800&type=headline&et_cid=5701621&et_rid=54636800&linkid=content)


Geologists say they have discovered the largest exposed fault on Earth in eastern Indonesia.

Led by Jonathan Pownall, Ph.D., from the Australian National University, researchers believe they have discovered a fault below the Banda Sea covering at least 60,000 kilometers.

“The abyss has been known for 90 years but until now no one has been able to explain how it got so deep,” Pownall said in a statement. “Our research found that a seven km-deep abyss beneath the Banda Sea off eastern Indonesia was formed by extension along what might be Earth's largest-identified exposed fault plane.”

Pownall said he believes that by studying the Banda Detachment fault they can better assess the dangers of future tsunamis in the Pacific Ring of Fire—which is particularly vulnerable to earthquakes and volcanic eruptions.

“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.


The original paper is free to view at GeoScience World (http://geology.geoscienceworld.org/content/44/11/947.full?ijkey=r0IjGZXS8x9Ro&keytype=ref&siteid=gsgeology).


Abstract

The Weber Deep—a 7.2-km-deep forearc basin within the tightly curved Banda arc of eastern Indonesia—is the deepest point of the Earth’s oceans not within a trench. Several models have been proposed to explain the tectonic evolution of the Banda arc in the context of the ongoing (ca. 23 Ma–present) Australia–Southeast Asia collision, but no model explicitly accounts for how the Weber Deep achieved its anomalous depth. Here we propose that the Weber Deep formed by forearc extension driven by eastward subduction rollback. Substantial lithospheric extension in the upper plate was accommodated by a major, previously unidentified, low-angle normal fault system we name the “Banda detachment.” High-resolution bathymetry data reveal that the Banda detachment is exposed underwater over much of its 120 km down-dip and 450 km lateral extent, having produced the largest bathymetric expression of any fault discernable in the world’s oceans. The Banda arc is a modern analogue for highly extended terranes preserved in the many regions that may similarly have “rolled open” behind migrating subduction zones.

geonuc
2016-Nov-29, 11:15 PM
I saw that in one of my geology feeds. Some complicated geology in that region - I had trouble visualizing the graphic..

By the way, I'm not sure where R&D got that 60,000 km figure from, but that length would more than wrap around the earth.

Grey
2016-Nov-30, 02:56 PM
By the way, I'm not sure where R&D got that 60,000 km figure from, but that length would more than wrap around the earth.I noticed the same thing. I'm wondering if it was supposed to be that the area of the exposed fault is 60,000 square km.

DaveC426913
2016-Nov-30, 09:22 PM
By the way, I'm not sure where R&D got that 60,000 km figure from, but that length would more than wrap around the earth.

Maybe it's fractal. :D

danscope
2016-Dec-19, 04:14 PM
No fault of their own.