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Rare ‘Boomerang’ earthquake followed by scientists in Ocean for the first time



Romanian Fracture Zone

Reconstructed image of the fracture area. Credit: Hicks et al.

Scientists observed a bo boomerang ̵

6;earthquake along the fault line of the Atlantic Ocean, providing clues as to how they could cause destruction on Earth.

Earthquakes occur when rocks suddenly explode a fault – a boundary between two blocks or slabs. During large earthquakes, rock breakage can spread to the fault line. Now, an international team of researchers has recorded a ‘bo boomerang’ earthquake, where the rupture initially spreads away from the initial break, but then reverses and drives back to other roads at higher speeds.

The strength and duration of rupture along a defect affect ground vibrations at the surface, which can damage buildings or create tsunamis. Ultimately, knowing the mechanisms of how fault breaks and physics involved will help researchers make better models and predictions of future earthquakes, and can inform earthquake early warning systems.

The team, led by scientists from the University of Southampton and Imperial College London, reported their results on Nature Geoscience is a peer-reviewed monthly journal, published by the Nature Publishing Group that covers all aspects of Earth sciences, including theoretical research, modeling, and fieldwork. Other related works have also been published in the fields of atmospheric sciences, geology, geophysics, climatology, oceanography, paleontology, and space science. Washt was established in January 2008.
“class =” glossaryLink “> Natural Geosciences
on August 10, 2020.

Breaking the seismic barrier of sound

While large earthquakes (magnitude 7 or higher) occur on the ground and are measured by nearby networks of observers (seismometers), these earthquakes often cause movement along complex networks of errors, like a series of dominoes. This makes it difficult to trace the underlying mechanisms of how this ‘seismic slip’ occurs.

Under the ocean, many fault types have simple shapes, so provide the opportunity to get under the cover of the ‘earthquake engine’. However, they are far from large networks of seismometers on the ground. The team used a new network of underwater seismometers to monitor the Romanche fracture zone, a fault line that lies 900 km below 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 the rupture initially traveled in one direction before turning in the middle of the road in the midst of the earthquake and breaking the ‘sound seismic barrier’, becoming an ultra-fast earthquake.

Only a handful of such earthquakes have been recorded globally. The team believes the first phase of rupture was crucial in causing the second phase, with sliding speed.

Earthquake prediction feed

The first author of the study, Dr. Stephen Hicks, from the Department of Earth Sciences and Engineering at Imperial, said: “While scientists have discovered that such a reversible decay mechanism is possible from theoretical models, our new study provides some of the clearest evidence for this mechanism. enigmatic that occurs in a real guilt.

“Although the structure of the fault seems simple, the way the earthquake grew was not, and it was the complete opposite of how we expected the earthquake to look before we started analyzing the data.”

However, the team says that if similar types of reversible earthquakes or boomerangs can occur on the ground, a seismic rupture that rotates around the middle through an earthquake can dramatically affect the amount of earthquake caused.

Given the lack of prior observational evidence, this mechanism has not been calculated for earthquake scenario modeling and risk assessments from such earthquakes. Detailed boomerang earthquake tracking can allow researchers to find similar patterns in other earthquakes and add new scenarios to their modeling and improve earthquake impact predictions.

The ocean floor seismometer network used was part of the PI-LAB and EUROLAB projects, a multimillion-dollar experiment funded by the UK Environmental Research Council, the European Research Council and the US National Science Foundation

Reference: “Supershear fracture that spreads to the back in M ​​2016w 7.1 Romanche Transforms the Earthquake of Guilt “by Stephen P. Hicks, Ryo Okuwaki, Andreas Steinberg, Catherine A. Rychert, Nicholas Harmon, Rachel E. Abercrombie, Petros Bogiatzis, David Schlaphorst, Jiri Zahradnik, J-Michael Kendall, Yuji Yagi, Kousuke Shimizu and Henriette Sudhaus, 10 August 2020, Natural geosciences.
DOI: 10.1038 / s41561-020-0619-9




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