Posted on 08/10/2020 8:35:18 PM PDT by BenLurkin
During large earthquakes, the breaking of rock can spread down the fault line. Now, an international team of researchers have recorded a 'boomerang' earthquake, where the rupture initially spreads away from initial break but then turns and runs back the other way at higher speeds.
The team, led by scientists from the University of Southampton and Imperial College London, report their results today in Nature Geoscience.
While large (magnitude 7 or higher) earthquakes occur on land and have been measured by nearby networks of monitors (seismometers), these earthquakes often trigger movement along complex networks of faults, like a series of dominoes. This makes it difficult to track the underlying mechanisms of how this 'seismic slip' occurs.
Under the ocean, many types of fault have simple shapes, so provide the possibility get under the bonnet of the 'earthquake engine'. ...The team made use of a new network of underwater seismometers to monitor the Romanche fracture zone, a fault line stretching 900km under the Atlantic near the equator.
In 2016, they recorded a magnitude 7.1 earthquake along the Romanche fracture zone and tracked the rupture along the fault. This revealed that initially the rupture traveled in one direction before turning around midway through the earthquake and breaking the 'seismic sound barrier', becoming an ultra-fast earthquake.
Only a handful of such earthquakes have been recorded globally. The team believe that the first phase of the rupture was crucial in causing the second, rapidly slipping phase.
Given the lack of observational evidence before now, this mechanism has been unaccounted for in earthquake scenario modeling and assessments of the hazards from such earthquakes. The detailed tracking of the boomerang earthquake could allow researchers to find similar patterns in other earthquakes and to add new scenarios into their modeling and improve earthquake impact forecasts.
(Excerpt) Read more at phys.org ...
ping
Sounds reasonable when you go back to the basic fact of what earthquakes represent, which are the results of large chunks of the thin shell encompassing the “fluid” mass of our planet shifting position.
Perhaps movement more pronounced in the third dimension is exacerbated by the position and motion of what might be considered as one of the significant influences on large earthquakes, our Moon.
Australia?
Australia is in the Pacific.
And boomerangs are in Australia.
Here in the Philippines the correct term then would likely be “yoyo”
“Even though the fault structure seems simple, the way the earthquake grew was not, and this was completely opposite to how we expected the earthquake to look before we started to analyze the data.”
Just when you think the science is settled...
Whatever.
You got it mate.
“And boomerangs are in Australia.”
Nice return.
I always rattleback. Euler? Euler? Must have the day off..
Unless the string breaks, then it's just a yo.
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.