Boomerang EarthquakeDate: 14 August 2020 Tags: Geography & Environment
In a first, scientists found evidence of a rare and unusual ‘boomerang’ earthquake that shook the deep seabed underneath the Atlantic Ocean in 2016.
Earthquakes occur when rocks suddenly break on a fault, but during a boomerang earthquake, the rupture initially spreads away from an initial break but then turns and runs back the other way at higher speeds.
A study was conducted by an international team of experts from the UK, the US, Germany, and Japan during which they examined the path one of these quakes under the Atlantic ocean.
While large (magnitude 7 or higher) earthquakes occur on land and have been measured by nearby networks of seismometers, these earthquakes often trigger movement along complex networks of faults, like a series of dominoes.
Notably, a magnitude 7.1 earthquake in the Atlantic Ocean back in 2016 was supposedly one of these rare types of earthquakes.
This earthquake took place along the Romanche fracture zone, which lies near the equator, roughly mid-way between the east coast of Brazil and the west coast of Africa.
Tracking the rupture along the fault, scientists observed that the rupture initially travelled in one direction. It then came back around for a second strike, bringing an increase of speed on the second strike by breaking the ‘seismic sound barrier’.
Whilst scientists have found that such a reversing rupture mechanism is possible from theoretical models, the new study provides some of the clearest evidence for this enigmatic mechanism occurring in a real fault.
Such earthquakes may help scientists assess potential hazards better, and implement more efficient warning systems for them in future.