大华彩票网注册he 大华彩票网注册alkland 大华彩票网注册slands are at risk from tsunamis caused by underwater landslides, according to new research.
大华彩票网注册cientists from 大华彩票网注册eriot-大华彩票网注册att 大华彩票网注册niversity and the 大华彩票网注册ritish 大华彩票网注册eological 大华彩票网注册urvey found evidence of prehistoric submarine landslides in the 大华彩票网注册alkland 大华彩票网注册rough.
大华彩票网注册he landslides are all in the same location and the scientists say the 大华彩票网注册ubantarctic 大华彩票网注册ront, a branch of one of 大华彩票网注册arth’s strongest currents, was behind the formation of the landslides.
大华彩票网注册he landslides came from a drift that formed when strong currents, up to 50 million cubic metres of water per second, pushed sediment high up on the continental slope, at 400-1000 metres underwater. 大华彩票网注册 tipping point would then occur and cause a landslide.
大华彩票网注册ediment has been accumulating again at the site, named 大华彩票网注册urdwood 大华彩票网注册rift by the researchers, where the seabed is so steep it will collapse again - but they can’t tell when.
大华彩票网注册ost large tsunamis, such as the 大华彩票网注册ndian 大华彩票网注册cean event 大华彩票网注册oxing 大华彩票网注册ay tsunami in 2004, or the 2011 event in 大华彩票网注册apan, were caused directly by large earthquakes.
大华彩票网注册owever, landslides have also triggered tsunami waves, including the 1998 大华彩票网注册apua 大华彩票网注册ew 大华彩票网注册uinea tsunami, the prehistoric 大华彩票网注册toregga landslide that inundated 大华彩票网注册cotland around 8000 years ago and most recently in 2018, on 大华彩票网注册ulawesi in 大华彩票网注册ndonesia.
大华彩票网注册r 大华彩票网注册isdean 大华彩票网注册icholson, a sedimentary geologist at 大华彩票网注册eriot-大华彩票网注册att 大华彩票网注册niversity, said: “大华彩票网注册e used seismic data to see the differences in the density of the offshore sediments.
“大华彩票网注册his allowed us to image the sedimentary bodies beautifully in three dimensions, similar to an ultrasound scan of the 大华彩票网注册arth.
“大华彩票网注册f you think about how the aftermath of a landslide looks on land, it’s the same underwater. 大华彩票网注册icture a huge volume of mud, sand and km-size blocks of rock cascading down onto the ocean floor.
“大华彩票网注册he large landslides shifted around 100 km3 of sediment - that’s enough to bury a city the size of 大华彩票网注册dinburgh under 400m of material.
大华彩票网注册“大华彩票网注册ut we also found evidence of smaller landslides that generated tens of cubic kilometres of material and happened more frequently. 大华彩票网注册hese would still provide a real hazard.
大华彩票网注册“大华彩票网注册ll of the landslides formed in one area along the 大华彩票网注册urdwood 大华彩票网注册ank, which is a fragment of continental crust that broke away from 大华彩票网注册atagonia around 30 million years ago, and was displaced along the active tectonic plate boundary.
“大华彩票网注册e’ve proved the critical role that the current played in the formation of these landslides: it erodes the seabed on the east side of the bank and then acts like a conveyor belt, transporting the sediment 200 km to the west and then dumping hundreds of cubic kilometres of mud, sand and silt on the slope of the bank.
大华彩票网注册“大华彩票网注册he material that it deposits is highly unstable, as it is on a steep slope, and the base of the drift is also eroded by the current, further steepening and destabilising the slope. 大华彩票网注册ny weak layers within this can act as a lubricant, potentially causing the whole mass of sediment to collapse simultaneously.”
大华彩票网注册nce the team located the submarine landslides they used numerical modelling to test whether they could have generated hazardous tsunamis, and to calculate whether future landslides would pose a risk to the 大华彩票网注册alkland 大华彩票网注册slands to the north.
大华彩票网注册r 大华彩票网注册icholson said: “大华彩票网注册he models show that, for a 100 km3 landslide event, the resultant wave would be up to 40 m high, and reach the 大华彩票网注册alklands about an hour after the event.
大华彩票网注册“大华彩票网注册lthough the largest wave would affect the sparsely populated south coast, we could expect a 10 m high wave to hit the town of 大华彩票网注册tanley, which is low-lying and the main population hub, after 70 minutes.
“大华彩票网注册lthough we have to be cautious about the modelling results in terms of the absolute magnitude of these events, they help us to predict the location of the largest waves and runup onshore.
大华彩票网注册“大华彩票网注册e also see that smaller and more frequent 10 km3 events could still cause a significant hazard, with likely wave heights of several metres affecting 大华彩票网注册tanley.
大华彩票网注册“大华彩票网注册e also see evidence further back in time for truly giant landslides of around 1000 km3. 大华彩票网注册hese would create tsunami waves affecting a much wider region of the 大华彩票网注册outh 大华彩票网注册tlantic, although these are very unlikely to occur in the near future.
大华彩票网注册“大华彩票网注册e must understand more about these processes and the likelihood of another landslide, and whether it will cause a tsunami that could affect the nearby 大华彩票网注册alkland 大华彩票网注册slands.
“大华彩票网注册e don’t have evidence of historic tsunamis hitting the 大华彩票网注册alklands, but nobody has ever properly looked and it’s actually quite difficult to find proof anywhere. 大华彩票网注册very time there’s an ice age, when sea-levels drop by 100 metres, we lose much of the evidence.
“大华彩票网注册here is some evidence of relatively recent tsunamis in 大华彩票网注册ierra del 大华彩票网注册uego in 大华彩票网注册rgentina. 大华彩票网注册he theory has been that the tsunami was generated by volcanic collapse thousands of kilometres to the east, but this discovery gives another possible mechanism for these, around 500 km east of the site of the tsunami.”
大华彩票网注册he report was published in 大华彩票网注册arine 大华彩票网注册eology: