think out vesuvius, mount st helens or mount krakatoa.'s two kilometres across, 850 metres deep. i'm not sure what that is in feet but it's an absolutely outstanding event. and we know that debris from this eruption has spread out after distances over 80 kilometres, and this debris is in the form of avalanches, underwater avalanches, underwater avalanches that have just completely smothered the seafloor, just destroyed all life and in places have buried the seafloor in up to 70 metres thick of new material. 50 the seafloor in up to 70 metres thick of new material.— thick of new material. so how do ou thick of new material. so how do you think _ thick of new material. so how do you think it _ thick of new material. so how do you think it compares - thick of new material. so how do you think it compares to l do you think it compares to other volcanoes? you mentioned sun bear. we other volcanoes? you mentioned sun bear. ~ ~ ., ., �*, sun bear. we know that, it's not on the — sun bear. we know that, it's not on the same _ sun bear. we know th

in 1883.- history, since possibly krakatoa in 1883. , , ., krakatoa in 1883.raordinarily powerful i was extraordinarily powerful but there are similar volcano lurking under water, of coastlands around the world. by understanding what happened and why, there may be lessons to help us prepare, in the future. tom brada, bbc news. paris has switched on its traditional christmas light display — this time, with an energy—efficient twist. it's part of a national effort to consume less electricity, as naomi choy smith reports. the countdown to christmas is on at the champs elysee. but this year the city of lights is shining just a little less brightly. these energy efficient champagne current led bulbs will be turned off earlier every night and run a week shorter than usual, consuming half the amount of electricity as last year's display. i electricity as last year's display-— electricity as last year's disla. ., ,. . display. i saw on the science they are _ display. i saw on the science they are using _ display. i saw on the science they are using less - display. i s

i mean, this was truly the most dramatic event in volcanic history since possibly krakatoa in 1883.re of the eruption? so, the problem we have with this particular volcano is it's an underwater volcano. if a volcano erupts on land, it's reasonably easy to assess the effects of that eruption by looking at fallen trees and you can actually clearly see the blast radius and debris that's flowed out but because this volcano was underwater, it requires quite a significant scientific expedition to actually go out to sea and actually map this area. we assumed, based on the size of the explosion, that an area of about 2000 square kilometres would be affected by this eruption — that's an area of about 20 kilometres radius from the volcano. but what we discovered once we mapped this is we didn't map enough. this volcano even exceeded our maximum expectations about how far the effects of this eruption was on the seafloor. it really was an absolutely outstanding event. and how has it changed the geological make—up of the area? well, surprisingly, the volcano itself is intact, and that's unusual

we note that krakatoa was a much larger event and there have been large events in the earlier 20th centurythe the pressure come from and why so exlosive? , . , ., ., , explosive? the secret is going to be an interaction _ explosive? the secret is going to be an interaction between _ explosive? the secret is going to be an interaction between the - explosive? the secret is going to be an interaction between the cold - explosive? the secret is going to be an interaction between the cold sea| an interaction between the cold sea water lava. that is not unusual, so there was another trigger but we know cold water interacting with the 1000 celsius lather will interact very explosively. water will flush to steam, so instantaneously you will get cubic miles of water exploding a thousand times of volume and shattering all the rock around it. we know the water is the big key but what is missing and what we really do not know is what turned it from a typical underwater explosion to the super one. we think it will be the fact that the entire magma chamber, reservoir of magma that sits under the volcan

i mean, this was truly the most dramatic event in volcanic history since possibly krakatoa in 1883.epare in the future. tom brada, bbc news. paris has switched on its traditional christmas light display. this year with an energy efficient twist. it is part of a national effort to consume less electricity. the on at the chance site. this year, the city of light shining a little less brightly. these efficient led bulbs will be turned off earlier every night and run a week shorter than usual, consuming half the amount of electricity as the display last year. tithe half the amount of electricity as the display last year.— half the amount of electricity as the display last year. one of the science that _ the display last year. one of the science that they _ the display last year. one of the science that they are _ the display last year. one of the science that they are using - the display last year. one of the science that they are using less | science that they are using less electricity this year, which is really cool. they also closed the road this year, which is incredible. they are

i mean, this was truly the most dramatic event in volcanic history since possibly krakatoa in 1883. so far. what we have now is this area of low pressure bringing this frontal system northwards and eastwards and in association with the some very strong winds through the some very strong winds through the afternoon, particularly across other parts of england. our band of rain continuing to track its way northwards and eastwards. northern ireland looking especially wet. salt —— scotland st clears spells and showers. temperatures at the very best up to 56 degrees. further south and west, highs of ten or 11. into the night, this low pressure centre taking rain further northwards, but that rain will stall and peter out. this area of low pressure swings in from the south—west. the isobars will squeeze together. there could be gales for a time around some exposed coasts in the south—west of england and the channel islands. this area of rain moving on the eastern side of scotland. one or two places will see a frost. it will not be quite as cold as it was last night. it could be quite a murk

i mean, this was truly the most dramatic event in volcanic history since possibly krakatoa in 1883. lurking underwater off coastlines around the world. by understanding what happened and why, there may be lessons to help us prepare in the future. tom brada, bbc news. paris has switched on its traditional christmas light display, this time with an energy—efficient twist. it's part of a national effort to consume less electricity, as naomi choy smith reports. the countdown to christmas is on at the champs—elysees. but this year, the city of lights is shining just a little less brightly. these energy—efficient champagne coloured led bulbs will be turned off earlier every night and run a week shorter than usual, consuming half the amount of electricity as last year's display. i saw one of the signs said that they're using less electricity this year, which is really cool, and i think they've also closed the road this year, which is incredible, so it's like they're sort of making these strides towards, i guess, greenerfuture, i guess, a greenerfuture, which is good to see. it's all part o

the instrumentation krakatoa in 1883.t was so big?— was so big? that is key question. what was it _ was so big? that is key question. what was it about _ was so big? that is key question. what was it about the _ was so big? that is key question. what was it about the structure i what was it about the structure which help to accelerate it in this degree? that is still an open question. in volcanology with volcanic eruptions, we have been studying them in detail for about 50, 60 years with modern implementation. there are records from all over the world. the impact of the eruptions are still growing. we are not really prepared for understanding just how big an impact even a larger eruption can have in terms of the global population, the global economy. you terms of the global population, the global economy-— terms of the global population, the global economy. you cannot get much further from — global economy. you cannot get much further from here _ global economy. you cannot get much further from here than _ global economy.