A elephantine boulder in Tonga ride a wave from an ancient tsunami 7,000 class ago . The 1,300 - ton rock traveled a distance twice the size of a football game field , swept forth by the bold forcefulness of the wave , according to a young discipline .
But this was no ordinary giant rock . It was also sitting on a 100 - animal foot ( 30 - meter ) tall drop before surfing to its young location — hinting at a past mega - tsunami that swept the region .
In July of 2024 , Martin Kohler , a PhD prospect from the University of Queensland , and his team were doing fieldwork on Tonga ’s cliffs , searching for grounds of retiring tsunamis . In particular , they were reckon for big boulders that could have been bear inland , which can tell researcher a lot about the account of tsunamis in earthquake - prone realm , like Tonga .
Max Kohler stands in front of the limestone boulder, Maka Lahi© University of Queensland
On one of their last subject days , some local farmers say the researcher about a boulder they might be concerned in . The stone , conversant to topical anaesthetic asMaka Lahi , or literally “ large rock , ” had never been analyze by scientists . It had in all likelihood eluded previous planet search for tsunami - traverse rocks because of its thickset coat of vegetation .
The boulder was made of coral reef limestone breccia , hinting that it had come from somewhere near the coast . “ I was so surprised ; it is locate far inland outdoors of our field work orbit and must have been carried by a very big tsunami , ” Kohler said in astatement . The researchers ’ findings were published in the journalMarine Geology .
The researchers later on found a immense slice in a 100 - foot ( 30 - metre ) tall cliff near the ocean , around 650 animal foot ( 200 meters ) off from the bowlder ’s current stance . They also determined the rock was deposited 6,891 year ago , before world steady down on Tonga .
The researchers measured the bowlder at 45 by 40 by 20 groundwork ( 14 by 12 by 7 meters ) eminent , roughly the size of a two - tarradiddle house . It now has the honor of being the third large tsunami - sweep up rock in the world . And it ’s the heavy boulder known to have surfed a tsunami from a cliff .
The team then used computer modelling to figure out about how tall the ancient tsunami that carriedMaka Lahimust have been . They concluded that the tsunami was , at minimum , 164 feet ( 50 measure ) marvellous and would have taken about a moment and a half to pop off . The tsunami in all likelihood attain speed of over 70 mile per minute ( 113 km per hr ) . It was huge and very powerful , and the researchers think a landslide , rather than an temblor , initially triggered the undulation .
Something Weird Happened 15 minute Before the Giant Tonga Eruption of 2022
Tonga sees a lot of geological activity that can actuate tsunamis , like thedevastating tsunami in 2022 . Understanding more about the mechanics of retiring tsunamis can help researcher better organize for future events , carbon monoxide - author Annie Lau , a coastal geomorphologist at the University of Queensland , said in a statement .
“ The analysis strengthens our understanding of wave transportation of rocks to amend coastal - jeopardy assessment in tsunami - prone regions around the public , ” Lau say .
Geologyrockstsunami
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