In August 2021 , a mysterious tsunami ruffle throughout the world , traveling an astonishing 10,000 kilometre ( 6,000 miles ) across three unlike sea . Seismologists were directly nonplus – there was a magnitude 7.5 quake in the south Atlantic straight prior to the tsunami , but at 47 kilometers ( 29 miles ) below the open , it was far too abstruse in the ocean to engender such a wave . The scientist discovered that the immense breach , spanning 400 kilometer ( 250 mile ) , should have ensue in a more significant earthquake , and the mystery has remained ever since .
Now , newfangled inquiry published in the journalGeophysical Research Letterssuggests the causative seism that occur near the South Sandwich Islands was not just one event , but really five individual hoagy - quakes in a course , hiding a shallower magnitude 8.2 temblor that lead in the far - reachingtsunami . Such a result paint a picture global earthquake monitoring may ask improvements to be able-bodied to key more complex temblor interactions .
Identifying deep - sea earthquakes is no easy task , and current seismological techniques only take abbreviated snapshot of the event . However , this does not always allow research worker with the full narrative , so Zhe Jia , Zhongwen Zhan , and Hiroo Kanamori delved into longer , 500 - second snip of the data to face for anything that could explain the tsunami . It was only then that they key out a 200 - second order of magnitude 8.2 quake that hit just 15 kilometers ( 9 miles ) below the surface , much shallow than the single event was believed to be . At this profoundness and order of magnitude , conditions were perfect to send a meaning tsunami riffle across the Earth’s surface . Yet , in the helter-skelter rumble of multiple other quake events , it overstep by undetected .
“ The third event is particular because it was vast , and it was unsounded , ” Jia said in astatement . “ In the data we commonly look at , it was almost inconspicuous . ”
In this brief 200 - second period , 70 percent of the total energy from all the quake combined was unblock , post a tsunami that trip across the Atlantic , Pacific , and Amerindic oceans . This tsunami was elementary , but the scientists are calling on seismologist to pick up from the study to meliorate foretelling of the side effect of earthquakes .
“ We take to rethink our manner to extenuate seism - tsunami hazard . To do that , we need to rapidly and accurately qualify the true size of big quake , as well as their physical processes , ” Jia said .
“ With these complex earthquakes , the quake happens and we think , ‘ Oh , that was n’t so big , we do n’t have to occupy . ’ And then thetsunami hitsand causes a lot of damage , ” said Judith Hubbard , geologist at the Earth Observatory of Singapore , who was not call for in the sketch .
