Africa-Press – Sierra-Leone. The 8.2-magnitude earthquake occurred about 15 km below Earth’s surface. Scientists have managed to finally identify the elusive earthquake that triggered a tsunami that spread thousands of kilometres from its epicentre through the North Atlantic, Pacific, and Indian oceans in August 2021.
As Live Science explains, while scientists originally believed that the tsunami in question was caused by a 7.5-magnitude earthquake detected near the South Sandwich Islands in the South Atlantic, its epicentre was simply too deep to cause a tsunami (about 47 km below the sea floor), and that the kind of the tectonic plate rupture that caused it (400 km long) “should have caused a much larger earthquake.”
A new study that was published in the Geophysical Research Letters journal earlier this month suggests that the earthquake was actually a sequence of five “sub-quakes,” and that the tsunami was caused by the third – an 8.2-magnitude“invisible” earthquake that occurred 15 km below Earth’s surface.
The quake apparently managed to avoid detection for so long because it was a hybrid of the deep rupture and slow tsunamigenic slip types of ocean earthquakes, with the latter often hard to detect despite being capable of releasing “just as much tectonic energy as a high-magnitude earthquake.”
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