1 00:00:00,209 --> 00:00:03,029 Our last hazards video ended with us saying... 2 00:00:03,180 --> 00:00:05,230 As you'll see in our next video, 3 00:00:05,239 --> 00:00:09,350 the real action happens along the edges of the tectonic plates. 4 00:00:09,710 --> 00:00:13,210 So, now it's time to take a look at plate boundaries, 5 00:00:13,220 --> 00:00:15,520 sometimes also called plate margins, 6 00:00:15,789 --> 00:00:20,069 which are all of the parts of the world where one tectonic plate is next to another. (MUSIC). 7 00:00:34,020 --> 00:00:39,200 Constructive sometimes also called divergent plate boundaries exist in the parts 8 00:00:39,209 --> 00:00:42,409 of the world where magma is rising up in the mantle below, 9 00:00:42,759 --> 00:00:45,450 this rising magma cools off and spreads out. 10 00:00:51,209 --> 00:00:54,270 Some of it solidifies and creates new crust which begins 11 00:00:54,279 --> 00:00:57,430 to slowly move apart as two separate tectonic plates. 12 00:00:58,450 --> 00:01:01,830 These types of boundary mostly appear at the bottom of the sea. 13 00:01:02,130 --> 00:01:02,200 (Under the sea). 14 00:01:03,270 --> 00:01:05,620 There are some places like Iceland where you can actually 15 00:01:05,629 --> 00:01:09,819 see evidence on land of the tectonic plates splitting apart. 16 00:01:09,989 --> 00:01:13,370 So, what type of hazards do we find here and why? 17 00:01:14,010 --> 00:01:16,239 Let's start with volcanoes. 18 00:01:16,470 --> 00:01:20,220 Some of the magma along with gases like carbon dioxide can 19 00:01:20,230 --> 00:01:23,269 melt through the crust and get released out of the surface, 20 00:01:23,769 --> 00:01:26,739 which is basically what a volcanic eruption is. 21 00:01:26,940 --> 00:01:27,830 So, yeah, 22 00:01:28,150 --> 00:01:30,980 we get volcanoes often with lots of lava. 23 00:01:31,900 --> 00:01:34,580 Earthquakes do happen at constructive boundaries, 24 00:01:34,589 --> 00:01:36,809 but they aren't usually that powerful. 25 00:01:36,940 --> 00:01:39,879 You see an earthquake happens when tectonic plates 26 00:01:39,889 --> 00:01:42,279 get stuck or grind against each other. 27 00:01:42,660 --> 00:01:44,589 And it just doesn't happen very much at this kind 28 00:01:44,599 --> 00:01:47,190 of boundary because the plates are mostly moving apart. 29 00:01:50,839 --> 00:01:51,769 Destructive, 30 00:01:51,779 --> 00:01:55,459 sometimes also called convergent boundaries are areas where 31 00:01:55,470 --> 00:01:58,180 tectonic plates are being carried towards each other. 32 00:01:58,279 --> 00:02:00,580 But there are actually two different types. 33 00:02:00,949 --> 00:02:04,419 If an oceanic plate is moving towards a continental plate, 34 00:02:04,519 --> 00:02:06,800 the oceanic plate is forced underneath because it 35 00:02:06,809 --> 00:02:10,059 is denser in a process we call subduction. 36 00:02:10,407 --> 00:02:14,328 As the oceanic plate sinks into the mantle, water and things like 37 00:02:14,339 --> 00:02:17,108 dead plankton on the sea floor are dragged down with it. 38 00:02:17,199 --> 00:02:21,328 These are turned into water vapor and carbon dioxide which bubble upwards 39 00:02:21,339 --> 00:02:25,289 and melt through the continental crust above get trapped in the rock. 40 00:02:25,298 --> 00:02:29,458 Pressure begins to build up much like it does when you shake a bottle of fizzy drink, 41 00:02:29,559 --> 00:02:33,098 and eventually the pressure in the crust becomes too great and the gas 42 00:02:33,108 --> 00:02:36,789 and lava violently explode out of the rock in a volcanic eruption. 43 00:02:37,869 --> 00:02:42,059 Extremely powerful earthquakes can also happen in these destructive boundaries. 44 00:02:42,080 --> 00:02:45,910 The oceanic crust doesn't simply slide gently past a continental plate. 45 00:02:46,220 --> 00:02:49,130 These huge rough slabs of rock are constantly 46 00:02:49,139 --> 00:02:51,610 grinding against and getting stuck on each other. 47 00:02:51,919 --> 00:02:54,059 And when they do get stuck, the continental 48 00:02:54,139 --> 00:02:56,919 plate starts getting dragged down with the oceanic plate. 49 00:02:57,399 --> 00:03:00,139 It builds up a huge amount of energy as this happens. 50 00:03:00,149 --> 00:03:02,210 And when the plates finally become unstuck, 51 00:03:02,399 --> 00:03:04,169 the plate violently jumps upwards, 52 00:03:04,179 --> 00:03:08,389 releasing all of the stored energy and causing intense shaking in the ground. 53 00:03:08,529 --> 00:03:10,279 We know this as an earthquake. 54 00:03:14,470 --> 00:03:19,020 The second type of destructive plate boundary is known as a collision boundary. 55 00:03:19,479 --> 00:03:23,169 The big difference here is that both of the tectonic plates are continental, 56 00:03:23,179 --> 00:03:25,070 so they have roughly the same density. 57 00:03:25,479 --> 00:03:30,809 They crash head-on and crumple upwards, creating what we call fold mountains. 58 00:03:31,720 --> 00:03:35,100 You can see this is happening between tectonic plates like the Indian and 59 00:03:35,110 --> 00:03:40,220 Eurasian plates where the force of the two plates colliding has created a mighty 60 00:03:40,399 --> 00:03:41,979 Himalayas mountain range. 61 00:03:43,529 --> 00:03:47,619 As you can imagine, the process of forming a mountain range isn't as smooth. 62 00:03:48,309 --> 00:03:52,630 The plates grind and crack and buckle upwards over millions of years 63 00:03:52,740 --> 00:03:56,320 and at times they get locked together and get stuck on each other. 64 00:03:56,710 --> 00:04:00,570 Eventually, the plates build up enough energy to become unstuck. 65 00:04:00,630 --> 00:04:04,190 The plates jolt back into movement and an earthquake is created. 66 00:04:04,800 --> 00:04:08,029 Oh and don't confuse these mountains of volcanoes. 67 00:04:08,570 --> 00:04:10,850 There's no magma rising up from underneath them, 68 00:04:10,860 --> 00:04:14,690 so you don't get any volcanic eruptions at collision boundaries. 69 00:04:18,820 --> 00:04:21,399 Conservative boundaries, sometimes also called 70 00:04:21,410 --> 00:04:23,920 transform boundaries are so named because 71 00:04:23,929 --> 00:04:27,459 the tectonic plates are not being constructed or destroyed here, 72 00:04:27,470 --> 00:04:30,779 so it is conserved which means to be kept the way it is. 73 00:04:31,049 --> 00:04:33,720 These conservative boundaries happen at places where two 74 00:04:33,730 --> 00:04:36,079 tectonic plates are sliding past each other, 75 00:04:36,459 --> 00:04:40,679 either in opposite directions or in the same direction at different speeds. 76 00:04:40,790 --> 00:04:44,500 The edges of the plate get stuck on each other as they grind past and 77 00:04:44,649 --> 00:04:46,019 you probably know the rest by now, 78 00:04:46,260 --> 00:04:50,269 it builds up energy and after a while they jolt back into moving again 79 00:04:50,429 --> 00:04:53,910 and the energy gets released causing the ground to shake, 80 00:04:54,079 --> 00:04:54,769 earthquake. 81 00:04:55,559 --> 00:04:57,779 Following the same rules as before, 82 00:04:57,790 --> 00:05:02,029 there is no magma rising up underneath the crust at a boundary like this. So, 83 00:05:02,170 --> 00:05:03,000 you guessed it, 84 00:05:03,390 --> 00:05:04,720 no volcanoes. 85 00:05:05,049 --> 00:05:06,970 And that will be all for this video. 86 00:05:07,839 --> 00:05:10,519 As always thank you very much for tuning in 87 00:05:10,529 --> 00:05:14,329 and if you enjoy our content, please consider liking and subscribing 88 00:05:14,500 --> 00:05:15,239 and also 89 00:05:15,670 --> 00:05:19,809 hit the little bell ding if you wish to be notified every time we upload a new video. 90 00:05:19,910 --> 00:05:20,839 As always, 91 00:05:20,850 --> 00:05:25,000 you've been listening to The Mountain Man and watching the work of Michael Deluxe. 92 00:05:25,079 --> 00:05:25,940 Remember, 93 00:05:26,230 --> 00:05:27,179 keep it simple. (MUSIC).