1 00:00:00,104 --> 00:00:04,527 we have talked a lot about the formations of mountains and volcanos 2 00:00:04,527 --> 00:00:07,504 when plates are running into each other or one plate is being 3 00:00:07,504 --> 00:00:10,929 subducted under another, but that isn't the only place 4 00:00:10,929 --> 00:00:16,208 it is the dominant place or the most likely place to find the mountains or volcanos on the surface of 5 00:00:16,208 --> 00:00:21,735 the earth. But that's not the only place that mountains of volcanos can form and probably the biggest example 6 00:00:21,735 --> 00:00:27,352 of volcanic activity or the most popular one, this might be a slightly American, Amero-centric point of view. 7 00:00:27,352 --> 00:00:35,324 But the most, often cited example of volcanic activity away from a plate boundary is Hawaii. 8 00:00:35,324 --> 00:00:44,412 Hawaii, so this right here, these are the hawaiian islands, this is the big island of hawaii, and it is, 9 00:00:44,412 --> 00:00:51,290 it is experiencing active, an active volcano. Lava is or magmas flowing from underneath the ground that 10 00:00:51,290 --> 00:00:59,832 once its surfaces we called it lava, and that lava is actively making the island,is actively making the island bigger, so where is 11 00:00:59,832 --> 00:01:05,976 that volcanic activity coming from and how can we think about that volcanic activity or that kind of heat 12 00:01:05,976 --> 00:01:12,943 rising from below the surface of the earth to explain some of the geological features we see around 13 00:01:12,943 --> 00:01:18,441 hawaii. So what we think is happening once again, this is all theory right here, is that hawaii is 14 00:01:18,441 --> 00:01:24,955 sitting on top of a hot spot, in particular, the big island of hawaii is sitting on the top of the hot spot 15 00:01:24,955 --> 00:01:31,504 right now, and this hot spot,this hot spot there is different ways or different theories on how it that 16 00:01:31,504 --> 00:01:37,448 emerge, but we think that at the mantle, at the mantle core boundary. I don't know if this diagram were 17 00:01:37,448 --> 00:01:43,317 intended this white area to be the core, but that's just say that this is the outter core down here. Let 18 00:01:43,317 --> 00:01:51,907 us just say this is the outter core, outter core for the sake of explaining things.We think it is possible 19 00:01:51,907 --> 00:01:58,749 that kind of plumes of very hot material can kind of.uh, just based on kind of flow dynamics of what 20 00:01:58,749 --> 00:02:05,357 is happening at that mantle outer core boundary that plumes are a really hot material can kind of rise 21 00:02:05,357 --> 00:02:13,239 up,can kind of - let me do this in a darker color - can rise up from outter core. It rises up from the outter core and create 22 00:02:13,239 --> 00:02:18,402 a hot spot underneath the moving lithospheric plate, underneath the plate, now it is not necessary, we don't know 23 00:02:18,402 --> 00:02:27,033 for sure, where these hot spots are being created from, by these mental plumes these materials formed, or heated 24 00:02:27,033 --> 00:02:31,950 up at the outter core mantle boundary, but we do feel pretty confident about is that there is 25 00:02:31,950 --> 00:02:38,562 this hot spot here and it's independent of any of those convection patterns that we saw. 26 00:02:38,562 --> 00:02:41,189 I shouldn't say independent, this is obviously all related, cause we have all these fluid commotion 27 00:02:41,189 --> 00:02:47,699 going on in the mantle, but it's, it's seperate on some degree from all those convection patterns that 28 00:02:47,699 --> 00:02:53,363 we have talked about, that could actually cause the plates to move,and to a large degree or the way we 29 00:02:53,363 --> 00:03:01,396 think about it right now, this is stationary, this hot spot is stationary, relative to the plates. And the 30 00:03:01,396 --> 00:03:07,263 reason why we feel pretty good about thinking that it's stationary relative to the plates, is we see this 31 00:03:07,263 --> 00:03:12,968 notion right here,if you look at the volcanic if you look at the volcanic rock in Kawaii, which is 32 00:03:12,968 --> 00:03:21,870 one of the older inhabited hawaiian islands. The oldest rock we observed there is 5.5 million years old, 33 00:03:21,870 --> 00:03:30,035 and it's all volcanic rock, now the oldest rock we observed on the big island is about 7 hundred thousand 34 00:03:30,035 --> 00:03:36,909 years old, we also know, we also know that the pacific plate, you could look at this diagram right over 35 00:03:36,909 --> 00:03:43,183 here is moving in this general direction, like we know it from, we know it from GPS measurements, is 36 00:03:43,183 --> 00:03:53,921 moving exactly in the direction, that the hawaiian islands are kind of distributed in. So uh,uh, frankly, the 37 00:03:53,921 --> 00:03:58,755 only good explanation for why we see this pattern, why we see this newer land here and then as we go further 38 00:03:58,755 --> 00:04:04,513 and further up the hawaiian island chain we see older and older land actually if we keep going, if we 39 00:04:04,513 --> 00:04:10,595 keep going we have the leeward islands over here as we, as we keep measuring the rock on the leeward island as we get older 40 00:04:10,595 --> 00:04:15,468 and older as you go to the northwest and if you even look at what's below the ocean. 41 00:04:15,499 --> 00:04:18,345 this is the big island of Hawaii 42 00:04:18,345 --> 00:04:20,550 these are the main Hawaiian islands,these are the leeward islands 43 00:04:20,550 --> 00:04:24,583 but you see even beyond that submersed under the Pacific Ocean, 44 00:04:24,583 --> 00:04:27,743 you continue to see a chain of islands. So, 45 00:04:27,743 --> 00:04:30,362 The explanation for what’s happening here, 46 00:04:30,362 --> 00:04:37,789 is that you have a stationary hot spot that is right now underneath the big island of Hawaii 47 00:04:37,789 --> 00:04:39,642 And I just wanna be clear, 48 00:04:39,642 --> 00:04:44,136 the big island is called the island of Hawaii, it is one of the islands in the state of Hawaii. 49 00:04:44,136 --> 00:04:46,257 So I don’t want cause you confusion. 50 00:04:46,257 --> 00:04:49,506 I’ll just call it the big island from here on out. 51 00:04:49,506 --> 00:04:51,434 So the hot spot is right under the big island. 52 00:04:51,434 --> 00:04:58,826 But if you were to rewind 5 million years ago, if you were to rewind 5 million years ago, the entire pacific plate 53 00:04:58,826 --> 00:05:05,067 the entire pacific plate was probably on the order of, you know, about 150, 200 miles, 54 00:05:05,067 --> 00:05:07,950 however far Kawaii is from the big island. 55 00:05:07,950 --> 00:05:15,081 It was probably shifted that much to the southeast, if you go back 5 million years ago. So 5 million years ago 56 00:05:15,081 --> 00:05:22,387 when all of this was shifted down and to the right, then Kawaii, Kawaii was on top of the hot spot. 57 00:05:22,387 --> 00:05:25,208 And so this is how each of these islands are formed. 58 00:05:25,208 --> 00:05:31,008 If you rewind a ton of years, then maybe this area over here in the Pacific plate was over the hot spot. 59 00:05:31,008 --> 00:05:35,590 Island- an island formed there then Pacific plate kept moving to the northwest. 60 00:05:35,590 --> 00:05:40,515 It kept moving to the northwest and new islands,new volcanos kept forming. 61 00:05:40,515 --> 00:05:43,657 Those volcanos would release lava that would keep piling up, 62 00:05:43,657 --> 00:05:47,511 keep piling up keep piling up, eventually, go above the surface of the water, 63 00:05:47,511 --> 00:05:54,338 and form this whole chain of islands, and as whole Pacific plate kept moving to the northwest, it kept forming new islands. 64 00:05:54,338 --> 00:05:59,151 Now the one question you might ask, is well, how come the big island is bigger? 65 00:05:59,151 --> 00:06:03,813 Has the plate kind of paused over there, is it spending more time over the hot spot 66 00:06:03,813 --> 00:06:08,021 so that more lava can kind of form there to form this, 67 00:06:08,021 --> 00:06:12,823 to form this- essentially it’s an underwater mountain that’s now also above the water 68 00:06:12,823 --> 00:06:20,381 and actually if you go from the base of the Pacific Ocean to the top of the big island of Hawaii it’s actually 50% higher than Mt. Everest, 69 00:06:20,381 --> 00:06:22,609 so you could really just view it as a big mountain 70 00:06:22,609 --> 00:06:27,712 But the question is this looks so much bigger than Kawaii they keep getting smaller as you keep going to northwest 71 00:06:27,712 --> 00:06:34,016 is somehow the Pacific plate slowing, is it spending more time here? And the answer is it’s probably not slowing, 72 00:06:34,016 --> 00:06:39,709 what’s happening is, at one time Kawaii was also probably a relatively large island. 73 00:06:39,709 --> 00:06:42,496 If you rewind 5, maybe 5 million years ago, 74 00:06:42,496 --> 00:06:49,773 Kawaii also might been about that big, but over 5 million years it’s just experienced the a ton of erosion. 75 00:06:49,773 --> 00:06:52,920 Remember, once it moved over the hot spot, new land wasn’t being created, 76 00:06:52,920 --> 00:06:55,767 it’s in the middle of the Pacific Ocean, its experiencing weather, 77 00:06:55,767 --> 00:07:01,705 5 million years is a long period of time, and so it just got eroded over that time. So the older the island is, 78 00:07:01,705 --> 00:07:04,679 the more eroded it’s going to be and the smaller it’s going to be. 79 00:07:04,679 --> 00:07:09,632 So if you go these, if you go to these under water mountains up here, that don’t even surface above the ocean 80 00:07:09,632 --> 00:07:12,531 at one time they might have surfaced, but over, due to the ocean and weather 81 00:07:12,531 --> 00:07:19,756 and whatnot they’ve just been eroded over time to become smaller and smaller, just kind of remnants of volcanos 82 00:07:19,756 --> 00:07:20,410 So anyway 83 00:07:20,425 --> 00:07:23,830 I thought you would find that entertaining, how the Hawaii islands 84 00:07:23,830 --> 00:07:27,282 actually got formed, and how we can actually have these hot spots, 85 00:07:27,282 --> 00:07:33,071 and these, this volcanic activity, and actually even earthquake activity, outside of actually 86 00:07:33,071 --> 00:07:35,252 eh, eh, eh plate boundaries. 87 00:07:35,252 --> 00:07:37,494 Actually while we’re looking at this diagram we talked about, 88 00:07:37,494 --> 00:07:39,556 we talked about the trenches of plate boundaries, 89 00:07:39,556 --> 00:07:42,248 you can actually see it here, cuz this shows the depth, 90 00:07:42,248 --> 00:07:46,571 and the really dark dark dark dark blue, it’s really dark deep parts of the ocean. 91 00:07:46,571 --> 00:07:48,795 So here is the Mariana Trench 92 00:07:48,795 --> 00:07:53,500 then you can see here over the Pacific plate just getting abducted-- not abducted- 93 00:07:53,500 --> 00:07:58,347 -- getting subducted into other plates, underneath and forms these trenches here. 94 00:07:58,347 --> 99:59:59,999 Anyway hopefully you found that entertaining.