0:00:00.209,0:00:03.029 Our last hazards video ended with us saying... 0:00:03.180,0:00:05.230 As you'll see in our next video, 0:00:05.239,0:00:09.350 the real action happens along the edges of the tectonic plates. 0:00:09.710,0:00:13.210 So, now it's time to take a look at plate boundaries, 0:00:13.220,0:00:15.520 sometimes also called plate margins, 0:00:15.789,0:00:20.069 which are all of the parts of the world where one tectonic plate is next to another. (MUSIC). 0:00:34.020,0:00:39.200 Constructive sometimes also called divergent plate boundaries exist in the parts 0:00:39.209,0:00:42.409 of the world where magma is rising up in the mantle below, 0:00:42.759,0:00:45.450 this rising magma cools off and spreads out. 0:00:51.209,0:00:54.270 Some of it solidifies and creates new crust which begins 0:00:54.279,0:00:57.430 to slowly move apart as two separate tectonic plates. 0:00:58.450,0:01:01.830 These types of boundary mostly appear at the bottom of the sea. 0:01:02.130,0:01:02.200 (Under the sea). 0:01:03.270,0:01:05.620 There are some places like Iceland where you can actually 0:01:05.629,0:01:09.819 see evidence on land of the tectonic plates splitting apart. 0:01:09.989,0:01:13.370 So, what type of hazards do we find here and why? 0:01:14.010,0:01:16.239 Let's start with volcanoes. 0:01:16.470,0:01:20.220 Some of the magma along with gases like carbon dioxide can 0:01:20.230,0:01:23.269 melt through the crust and get released out of the surface, 0:01:23.769,0:01:26.739 which is basically what a volcanic eruption is. 0:01:26.940,0:01:27.830 So, yeah, 0:01:28.150,0:01:30.980 we get volcanoes often with lots of lava. 0:01:31.900,0:01:34.580 Earthquakes do happen at constructive boundaries, 0:01:34.589,0:01:36.809 but they aren't usually that powerful. 0:01:36.940,0:01:39.879 You see an earthquake happens when tectonic plates 0:01:39.889,0:01:42.279 get stuck or grind against each other. 0:01:42.660,0:01:44.589 And it just doesn't happen very much at this kind 0:01:44.599,0:01:47.190 of boundary because the plates are mostly moving apart. 0:01:50.839,0:01:51.769 Destructive, 0:01:51.779,0:01:55.459 sometimes also called convergent boundaries are areas where 0:01:55.470,0:01:58.180 tectonic plates are being carried towards each other. 0:01:58.279,0:02:00.580 But there are actually two different types. 0:02:00.949,0:02:04.419 If an oceanic plate is moving towards a continental plate, 0:02:04.519,0:02:06.800 the oceanic plate is forced underneath because it 0:02:06.809,0:02:10.059 is denser in a process we call subduction. 0:02:10.407,0:02:14.328 As the oceanic plate sinks into the mantle, water and things like 0:02:14.339,0:02:17.108 dead plankton on the sea floor are dragged down with it. 0:02:17.199,0:02:21.328 These are turned into water vapor and carbon dioxide which bubble upwards 0:02:21.339,0:02:25.289 and melt through the continental crust above get trapped in the rock. 0:02:25.298,0:02:29.458 Pressure begins to build up much like it does when you shake a bottle of fizzy drink, 0:02:29.559,0:02:33.098 and eventually the pressure in the crust becomes too great and the gas 0:02:33.108,0:02:36.789 and lava violently explode out of the rock in a volcanic eruption. 0:02:37.869,0:02:42.059 Extremely powerful earthquakes can also happen in these destructive boundaries. 0:02:42.080,0:02:45.910 The oceanic crust doesn't simply slide gently past a continental plate. 0:02:46.220,0:02:49.130 These huge rough slabs of rock are constantly 0:02:49.139,0:02:51.610 grinding against and getting stuck on each other. 0:02:51.919,0:02:54.059 And when they do get stuck, the continental 0:02:54.139,0:02:56.919 plate starts getting dragged down with the oceanic plate. 0:02:57.399,0:03:00.139 It builds up a huge amount of energy as this happens. 0:03:00.149,0:03:02.210 And when the plates finally become unstuck, 0:03:02.399,0:03:04.169 the plate violently jumps upwards, 0:03:04.179,0:03:08.389 releasing all of the stored energy and causing intense shaking in the ground. 0:03:08.529,0:03:10.279 We know this as an earthquake. 0:03:14.470,0:03:19.020 The second type of destructive plate boundary is known as a collision boundary. 0:03:19.479,0:03:23.169 The big difference here is that both of the tectonic plates are continental, 0:03:23.179,0:03:25.070 so they have roughly the same density. 0:03:25.479,0:03:30.809 They crash head-on and crumple upwards, creating what we call fold mountains. 0:03:31.720,0:03:35.100 You can see this is happening between tectonic plates like the Indian and 0:03:35.110,0:03:40.220 Eurasian plates where the force of the two plates colliding has created a mighty 0:03:40.399,0:03:41.979 Himalayas mountain range. 0:03:43.529,0:03:47.619 As you can imagine, the process of forming a mountain range isn't as smooth. 0:03:48.309,0:03:52.630 The plates grind and crack and buckle upwards over millions of years 0:03:52.740,0:03:56.320 and at times they get locked together and get stuck on each other. 0:03:56.710,0:04:00.570 Eventually, the plates build up enough energy to become unstuck. 0:04:00.630,0:04:04.190 The plates jolt back into movement and an earthquake is created. 0:04:04.800,0:04:08.029 Oh and don't confuse these mountains of volcanoes. 0:04:08.570,0:04:10.850 There's no magma rising up from underneath them, 0:04:10.860,0:04:14.690 so you don't get any volcanic eruptions at collision boundaries. 0:04:18.820,0:04:21.399 Conservative boundaries, sometimes also called 0:04:21.410,0:04:23.920 transform boundaries are so named because 0:04:23.929,0:04:27.459 the tectonic plates are not being constructed or destroyed here, 0:04:27.470,0:04:30.779 so it is conserved which means to be kept the way it is. 0:04:31.049,0:04:33.720 These conservative boundaries happen at places where two 0:04:33.730,0:04:36.079 tectonic plates are sliding past each other, 0:04:36.459,0:04:40.679 either in opposite directions or in the same direction at different speeds. 0:04:40.790,0:04:44.500 The edges of the plate get stuck on each other as they grind past and 0:04:44.649,0:04:46.019 you probably know the rest by now, 0:04:46.260,0:04:50.269 it builds up energy and after a while they jolt back into moving again 0:04:50.429,0:04:53.910 and the energy gets released causing the ground to shake, 0:04:54.079,0:04:54.769 earthquake. 0:04:55.559,0:04:57.779 Following the same rules as before, 0:04:57.790,0:05:02.029 there is no magma rising up underneath the crust at a boundary like this. So, 0:05:02.170,0:05:03.000 you guessed it, 0:05:03.390,0:05:04.720 no volcanoes. 0:05:05.049,0:05:06.970 And that will be all for this video. 0:05:07.839,0:05:10.519 As always thank you very much for tuning in 0:05:10.529,0:05:14.329 and if you enjoy our content, please consider liking and subscribing 0:05:14.500,0:05:15.239 and also 0:05:15.670,0:05:19.809 hit the little bell ding if you wish to be notified every time we upload a new video. 0:05:19.910,0:05:20.839 As always, 0:05:20.850,0:05:25.000 you've been listening to The Mountain Man and watching the work of Michael Deluxe. 0:05:25.079,0:05:25.940 Remember, 0:05:26.230,0:05:27.179 keep it simple. (MUSIC).