WEBVTT 00:00:00.209 --> 00:00:03.029 Our last hazards video ended with us saying... 00:00:03.180 --> 00:00:05.230 As you'll see in our next video, 00:00:05.239 --> 00:00:09.350 the real action happens along the edges of the tectonic plates. 00:00:09.710 --> 00:00:13.210 So, now it's time to take a look at plate boundaries, 00:00:13.220 --> 00:00:15.520 sometimes also called plate margins, 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). 00:00:34.020 --> 00:00:39.200 Constructive sometimes also called divergent plate boundaries exist in the parts 00:00:39.209 --> 00:00:42.409 of the world where magma is rising up in the mantle below, 00:00:42.759 --> 00:00:45.450 this rising magma cools off and spreads out. 00:00:51.209 --> 00:00:54.270 Some of it solidifies and creates new crust which begins 00:00:54.279 --> 00:00:57.430 to slowly move apart as two separate tectonic plates. 00:00:58.450 --> 00:01:01.830 These types of boundary mostly appear at the bottom of the sea. 00:01:02.130 --> 00:01:02.200 (Under the sea). 00:01:03.270 --> 00:01:05.620 There are some places like Iceland where you can actually 00:01:05.629 --> 00:01:09.819 see evidence on land of the tectonic plates splitting apart. 00:01:09.989 --> 00:01:13.370 So, what type of hazards do we find here and why? 00:01:14.010 --> 00:01:16.239 Let's start with volcanoes. 00:01:16.470 --> 00:01:20.220 Some of the magma along with gases like carbon dioxide can 00:01:20.230 --> 00:01:23.269 melt through the crust and get released out of the surface, 00:01:23.769 --> 00:01:26.739 which is basically what a volcanic eruption is. 00:01:26.940 --> 00:01:27.830 So, yeah, 00:01:28.150 --> 00:01:30.980 we get volcanoes often with lots of lava. 00:01:31.900 --> 00:01:34.580 Earthquakes do happen at constructive boundaries, 00:01:34.589 --> 00:01:36.809 but they aren't usually that powerful. 00:01:36.940 --> 00:01:39.879 You see an earthquake happens when tectonic plates 00:01:39.889 --> 00:01:42.279 get stuck or grind against each other. 00:01:42.660 --> 00:01:44.589 And it just doesn't happen very much at this kind 00:01:44.599 --> 00:01:47.190 of boundary because the plates are mostly moving apart. 00:01:50.839 --> 00:01:51.769 Destructive, 00:01:51.779 --> 00:01:55.459 sometimes also called convergent boundaries are areas where 00:01:55.470 --> 00:01:58.180 tectonic plates are being carried towards each other. 00:01:58.279 --> 00:02:00.580 But there are actually two different types. 00:02:00.949 --> 00:02:04.419 If an oceanic plate is moving towards a continental plate, 00:02:04.519 --> 00:02:06.800 the oceanic plate is forced underneath because it 00:02:06.809 --> 00:02:10.059 is denser in a process we call subduction. 00:02:10.407 --> 00:02:14.328 As the oceanic plate sinks into the mantle, water and things like 00:02:14.339 --> 00:02:17.108 dead plankton on the sea floor are dragged down with it. 00:02:17.199 --> 00:02:21.328 These are turned into water vapor and carbon dioxide which bubble upwards 00:02:21.339 --> 00:02:25.289 and melt through the continental crust above get trapped in the rock. 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, 00:02:29.559 --> 00:02:33.098 and eventually the pressure in the crust becomes too great and the gas 00:02:33.108 --> 00:02:36.789 and lava violently explode out of the rock in a volcanic eruption. 00:02:37.869 --> 00:02:42.059 Extremely powerful earthquakes can also happen in these destructive boundaries. 00:02:42.080 --> 00:02:45.910 The oceanic crust doesn't simply slide gently past a continental plate. 00:02:46.220 --> 00:02:49.130 These huge rough slabs of rock are constantly 00:02:49.139 --> 00:02:51.610 grinding against and getting stuck on each other. 00:02:51.919 --> 00:02:54.059 And when they do get stuck, the continental 00:02:54.139 --> 00:02:56.919 plate starts getting dragged down with the oceanic plate. 00:02:57.399 --> 00:03:00.139 It builds up a huge amount of energy as this happens. 00:03:00.149 --> 00:03:02.210 And when the plates finally become unstuck, 00:03:02.399 --> 00:03:04.169 the plate violently jumps upwards, 00:03:04.179 --> 00:03:08.389 releasing all of the stored energy and causing intense shaking in the ground. 00:03:08.529 --> 00:03:10.279 We know this as an earthquake. 00:03:14.470 --> 00:03:19.020 The second type of destructive plate boundary is known as a collision boundary. 00:03:19.479 --> 00:03:23.169 The big difference here is that both of the tectonic plates are continental, 00:03:23.179 --> 00:03:25.070 so they have roughly the same density. 00:03:25.479 --> 00:03:30.809 They crash head-on and crumple upwards, creating what we call fold mountains. 00:03:31.720 --> 00:03:35.100 You can see this is happening between tectonic plates like the Indian and 00:03:35.110 --> 00:03:40.220 Eurasian plates where the force of the two plates colliding has created a mighty 00:03:40.399 --> 00:03:41.979 Himalayas mountain range. 00:03:43.529 --> 00:03:47.619 As you can imagine, the process of forming a mountain range isn't as smooth. 00:03:48.309 --> 00:03:52.630 The plates grind and crack and buckle upwards over millions of years 00:03:52.740 --> 00:03:56.320 and at times they get locked together and get stuck on each other. 00:03:56.710 --> 00:04:00.570 Eventually, the plates build up enough energy to become unstuck. 00:04:00.630 --> 00:04:04.190 The plates jolt back into movement and an earthquake is created. 00:04:04.800 --> 00:04:08.029 Oh and don't confuse these mountains of volcanoes. 00:04:08.570 --> 00:04:10.850 There's no magma rising up from underneath them, 00:04:10.860 --> 00:04:14.690 so you don't get any volcanic eruptions at collision boundaries. 00:04:18.820 --> 00:04:21.399 Conservative boundaries, sometimes also called 00:04:21.410 --> 00:04:23.920 transform boundaries are so named because 00:04:23.929 --> 00:04:27.459 the tectonic plates are not being constructed or destroyed here, 00:04:27.470 --> 00:04:30.779 so it is conserved which means to be kept the way it is. 00:04:31.049 --> 00:04:33.720 These conservative boundaries happen at places where two 00:04:33.730 --> 00:04:36.079 tectonic plates are sliding past each other, 00:04:36.459 --> 00:04:40.679 either in opposite directions or in the same direction at different speeds. 00:04:40.790 --> 00:04:44.500 The edges of the plate get stuck on each other as they grind past and 00:04:44.649 --> 00:04:46.019 you probably know the rest by now, 00:04:46.260 --> 00:04:50.269 it builds up energy and after a while they jolt back into moving again 00:04:50.429 --> 00:04:53.910 and the energy gets released causing the ground to shake, 00:04:54.079 --> 00:04:54.769 earthquake. 00:04:55.559 --> 00:04:57.779 Following the same rules as before, 00:04:57.790 --> 00:05:02.029 there is no magma rising up underneath the crust at a boundary like this. So, 00:05:02.170 --> 00:05:03.000 you guessed it, 00:05:03.390 --> 00:05:04.720 no volcanoes. 00:05:05.049 --> 00:05:06.970 And that will be all for this video. 00:05:07.839 --> 00:05:10.519 As always thank you very much for tuning in 00:05:10.529 --> 00:05:14.329 and if you enjoy our content, please consider liking and subscribing 00:05:14.500 --> 00:05:15.239 and also 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. 00:05:19.910 --> 00:05:20.839 As always, 00:05:20.850 --> 00:05:25.000 you've been listening to The Mountain Man and watching the work of Michael Deluxe. 00:05:25.079 --> 00:05:25.940 Remember, 00:05:26.230 --> 00:05:27.179 keep it simple. (MUSIC).