1 00:00:00,000 --> 00:00:04,162 WWW.MY-SUBS.CO 1 00:00:02,865 --> 00:00:05,165 >> Earth--a unique planet-- 2 00:00:05,466 --> 00:00:07,666 restless and dynamic 3 00:00:08,866 --> 00:00:11,969 Continents shift and clash. 4 00:00:12,036 --> 00:00:16,139 volcanoes erupt, glaciers grow 5 00:00:16,207 --> 00:00:19,309 and recede. Titanic forces that 6 00:00:19,344 --> 00:00:22,045 are constantly at work, leaving 7 00:00:22,146 --> 00:00:24,615 behind a trail of geological 8 00:00:24,682 --> 00:00:29,152 mysteries. 9 00:00:29,220 --> 00:00:31,054 One of earth's most intriguing 10 00:00:31,122 --> 00:00:32,522 mysteries is the presence of 11 00:00:32,590 --> 00:00:34,491 a huge arc of geological 12 00:00:34,525 --> 00:00:35,959 destruction surrounding the 13 00:00:36,060 --> 00:00:37,494 Pacific. 14 00:00:37,528 --> 00:00:41,231 It is known as the Ring of Fire. 15 00:00:41,332 --> 00:00:42,666 Three-quarters of earth's 16 00:00:42,700 --> 00:00:44,968 volcanoes are situated here... 17 00:00:45,069 --> 00:00:47,504 And 90% of all earthquakes also 18 00:00:47,605 --> 00:00:51,708 occur along this line. 19 00:00:51,776 --> 00:00:54,044 Over the last 200 years, 20 00:00:54,112 --> 00:00:55,779 disasters here have claimed over 21 00:00:55,880 --> 00:00:57,614 one million lives. 22 00:01:01,519 --> 00:01:03,787 Now scientists set out to 23 00:01:03,855 --> 00:01:05,589 discover why these volcanoes 24 00:01:05,690 --> 00:01:07,324 and quakes occur all around the 25 00:01:07,425 --> 00:01:10,694 margins of the Pacific Ocean and 26 00:01:10,795 --> 00:01:14,431 to find out what powers them. 27 00:01:14,499 --> 00:01:15,966 Unlocking the mysteries of this 28 00:01:16,034 --> 00:01:17,668 awesome force of geology will 29 00:01:17,702 --> 00:01:19,469 bring the scientists one step 30 00:01:19,504 --> 00:01:20,971 closer to understanding 31 00:01:21,039 --> 00:01:23,306 How the Earth was Made. 32 00:01:23,341 --> 00:01:26,143 S02x07 Ring of Fire Original Air Date on January 22, 2009 33 00:01:26,210 --> 00:01:28,779 -- Sync, corrected by 00:01:30,313 The Ring of Fire is one of 35 00:01:30,381 --> 00:01:31,481 the most extensive zones of 36 00:01:31,516 --> 00:01:33,650 destruction on planet earth. 37 00:01:33,685 --> 00:01:35,218 Its most visible features are 38 00:01:35,286 --> 00:01:36,920 the hundreds of volcanoes that 39 00:01:36,954 --> 00:01:38,488 line the shores of the Pacific 40 00:01:38,556 --> 00:01:42,693 Ocean. They form an arc 41 00:01:42,760 --> 00:01:46,329 which extends 25,000 miles, 42 00:01:46,397 --> 00:01:47,764 from South America 43 00:01:47,832 --> 00:01:50,133 along America's northwest coast 44 00:01:50,201 --> 00:01:53,303 to Alaska and then down 45 00:01:53,337 --> 00:01:56,273 through Russia, Japan, and 46 00:01:56,374 --> 00:01:58,108 Southeast Asia 47 00:01:58,209 --> 00:02:00,911 all the way to New Zealand. 48 00:02:00,978 --> 00:02:02,379 Cataclysmic eruptions have 49 00:02:02,447 --> 00:02:03,714 occurred here throughout 50 00:02:03,748 --> 00:02:06,183 history. 51 00:02:10,822 --> 00:02:16,259 August, 1883. Indonesia. 52 00:02:16,294 --> 00:02:19,529 The krakatoa volcano blew itself 53 00:02:19,564 --> 00:02:23,567 to pieces, creating the loudest 54 00:02:23,634 --> 00:02:27,270 sound in recorded history. 55 00:02:27,338 --> 00:02:31,541 June, 1991. The philippines. 56 00:02:31,642 --> 00:02:33,744 Mount Pinatubo blasted debris 57 00:02:33,811 --> 00:02:37,114 22 miles into the atmosphere. 58 00:02:37,181 --> 00:02:39,015 Suffocating ash swamped over 59 00:02:39,083 --> 00:02:43,019 2,500 square miles. 60 00:02:43,087 --> 00:02:44,921 And in may 1980, 61 00:02:44,989 --> 00:02:46,523 Mount St. Helens caused 62 00:02:46,557 --> 00:02:50,927 $1 billion of damage. 63 00:02:50,995 --> 00:02:52,629 The ever-present threat from 64 00:02:52,697 --> 00:02:53,730 these volcanoes makes it 65 00:02:53,798 --> 00:02:55,098 essential for scientists to 66 00:02:55,166 --> 00:02:56,533 understand the forces that 67 00:02:56,567 --> 00:03:01,538 power them. The investigation 68 00:03:01,572 --> 00:03:05,442 begins here in Alaska. 69 00:03:05,510 --> 00:03:07,110 This land of rugged beauty 70 00:03:07,178 --> 00:03:09,279 marks the most northern extreme 71 00:03:09,347 --> 00:03:12,082 of the Ring of Fire. 72 00:03:12,150 --> 00:03:14,451 75% of all the volcanoes in the 73 00:03:14,552 --> 00:03:16,520 United States are situated in 74 00:03:16,554 --> 00:03:18,922 Alaska, making it a perfect 75 00:03:18,990 --> 00:03:23,527 laboratory for volcanologists. 76 00:03:23,628 --> 00:03:25,262 The first step is to discover 77 00:03:25,329 --> 00:03:26,897 how the Ring of Fire's giant 78 00:03:26,998 --> 00:03:28,899 volcanoes form. 79 00:03:34,806 --> 00:03:35,806 >> We're headed to 80 00:03:35,873 --> 00:03:38,141 Augustine Volcano, which lies in 81 00:03:38,176 --> 00:03:41,511 Cook Inlet, and it's part of the 82 00:03:41,512 --> 00:03:42,913 chain of volcanoes that extends 83 00:03:42,980 --> 00:03:44,714 all the way down into the 84 00:03:44,782 --> 00:03:46,616 Aleutian Islands. 85 00:03:46,717 --> 00:03:48,451 >> It's a 60-mile journey out 86 00:03:48,553 --> 00:03:51,822 across the frigid Alaskan water. 87 00:03:51,889 --> 00:03:54,090 In the distance, the volcano 88 00:03:54,158 --> 00:03:57,093 soon appears. 89 00:03:57,161 --> 00:03:58,595 >> There's Augustine Volcano 90 00:03:58,663 --> 00:04:00,397 over there. It's gonna 91 00:04:00,498 --> 00:04:02,933 be a perfect day to visit. 92 00:04:02,967 --> 00:04:04,501 >> From high above the clouds, 93 00:04:04,602 --> 00:04:06,469 Dr. Bull can gain a clear view 94 00:04:06,571 --> 00:04:08,138 of the volcano's distinctive 95 00:04:08,206 --> 00:04:11,508 outline. 96 00:04:11,609 --> 00:04:14,044 Augustine is a stratovolcano-- 97 00:04:14,145 --> 00:04:16,046 the type of volcano found all 98 00:04:16,113 --> 00:04:18,748 around the Ring of Fire. 99 00:04:18,783 --> 00:04:19,583 >> Stratovolcanoes are 100 00:04:19,684 --> 00:04:20,784 quite unique in that they are 101 00:04:20,852 --> 00:04:23,854 shaped as beautiful cones. And 102 00:04:23,955 --> 00:04:25,222 Augustine is a perfect example 103 00:04:25,289 --> 00:04:26,690 of that. 104 00:04:26,791 --> 00:04:28,124 >> Augustine last exploded in 105 00:04:28,226 --> 00:04:31,862 January 2006--the most recent 106 00:04:31,863 --> 00:04:37,467 of 7 eruptions here since 1935. 107 00:04:37,468 --> 00:04:39,469 Over the years, solidified lava 108 00:04:39,503 --> 00:04:41,137 flows have gradually built up 109 00:04:41,205 --> 00:04:45,742 on the volcano's flanks. 110 00:04:45,776 --> 00:04:47,644 To investigate what makes these 111 00:04:47,678 --> 00:04:50,180 volcanoes dangerous, Dr. Bull 112 00:04:50,281 --> 00:04:52,015 climbs high up on the side of 113 00:04:52,116 --> 00:04:54,384 one of these lava flows. 114 00:04:54,452 --> 00:04:56,920 >> This lava is made up 115 00:04:56,988 --> 00:04:58,788 of blocks. There's bits that 116 00:04:58,823 --> 00:05:02,826 are a little denser than others. 117 00:05:02,894 --> 00:05:04,661 And you can see there's a lot 118 00:05:04,729 --> 00:05:07,297 of different pieces to it. So we 119 00:05:07,365 --> 00:05:11,835 call this a blocky lava flow. 120 00:05:11,903 --> 00:05:13,637 >> This blocky lava provides 121 00:05:13,638 --> 00:05:16,006 a crucial clue as to why 122 00:05:16,007 --> 00:05:17,340 the Ring of Fire volcanoes 123 00:05:17,375 --> 00:05:21,077 can be so deadly. 124 00:05:21,178 --> 00:05:23,813 >> This lava is more thick when 125 00:05:23,915 --> 00:05:25,715 it comes out of the volcano. 126 00:05:25,816 --> 00:05:28,418 And its thickness will have 127 00:05:28,452 --> 00:05:30,654 an effect on how it runs down 128 00:05:30,721 --> 00:05:33,423 the slope. 129 00:05:33,457 --> 00:05:34,925 The thickness or viscosity of 130 00:05:34,992 --> 00:05:37,627 lavas can be shown in a number 131 00:05:37,695 --> 00:05:38,995 of ways. 132 00:05:39,096 --> 00:05:42,165 Hawaii lavas are quite runny. 133 00:05:42,266 --> 00:05:45,168 Honey is a perfect example of 134 00:05:45,269 --> 00:05:47,537 that. If you have a volcano 135 00:05:47,605 --> 00:05:50,006 putting out Hawaii-like lava, 136 00:05:50,074 --> 00:05:51,541 it's gonna run quite easily 137 00:05:51,609 --> 00:05:55,245 down the rock whereas if you 138 00:05:55,279 --> 00:05:57,447 have something more like 139 00:05:57,548 --> 00:06:00,183 these blocky lavas, 140 00:06:00,284 --> 00:06:01,451 they're gonna be a little bit 141 00:06:01,552 --> 00:06:03,153 more like peanut butter. 142 00:06:03,187 --> 00:06:04,154 And they'll still run, but 143 00:06:04,188 --> 00:06:07,324 the viscosity is much greater. 144 00:06:07,358 --> 00:06:09,059 >> The viscosity of lava is 145 00:06:09,093 --> 00:06:10,527 primarily determined by the 146 00:06:10,594 --> 00:06:14,164 amount of silica it contains. 147 00:06:14,231 --> 00:06:16,066 Silica is the most abundant 148 00:06:16,100 --> 00:06:19,502 mineral in earth's crust. 149 00:06:19,537 --> 00:06:21,004 >> The more silica, 150 00:06:21,072 --> 00:06:22,605 the thicker or more viscous 151 00:06:22,640 --> 00:06:25,308 the lava is likely to be. 152 00:06:25,376 --> 00:06:27,077 >> Hawaiian lava contains little 153 00:06:27,178 --> 00:06:29,379 silica, so it's runny and 154 00:06:29,447 --> 00:06:31,247 produces a relatively flat 155 00:06:31,282 --> 00:06:34,184 landscape, but Ring of Fire 156 00:06:34,251 --> 00:06:36,553 lavas are rich in silica, 157 00:06:36,620 --> 00:06:37,620 making them sticky 158 00:06:37,688 --> 00:06:39,689 and less able to flow, creating 159 00:06:39,724 --> 00:06:41,358 tall, cone-shaped 160 00:06:41,425 --> 00:06:45,996 stratovolcanoes. 161 00:06:46,097 --> 00:06:48,365 During the 2006 eruption of 162 00:06:48,432 --> 00:06:49,699 Augustine, thermal imaging 163 00:06:49,800 --> 00:06:51,501 cameras were used to study the 164 00:06:51,535 --> 00:06:54,971 volcano. 165 00:06:55,072 --> 00:06:56,506 They show this sticky lava 166 00:06:56,507 --> 00:06:57,440 building up 167 00:06:57,441 --> 00:07:00,977 layer upon layer. 168 00:07:01,078 --> 00:07:02,612 But the thickness of this 169 00:07:02,680 --> 00:07:04,714 lava also makes these volcanoes 170 00:07:04,815 --> 00:07:06,983 lethal. 171 00:07:07,051 --> 00:07:09,085 >> Because these volcanoes have 172 00:07:09,153 --> 00:07:11,454 lava that is thick, 173 00:07:11,522 --> 00:07:12,455 things don't move 174 00:07:12,523 --> 00:07:14,724 through them very well and 175 00:07:14,792 --> 00:07:19,629 bubbles of gases can build up. 176 00:07:19,697 --> 00:07:21,464 >> Deep in the earth under 177 00:07:21,499 --> 00:07:23,400 immense pressure, molten rock 178 00:07:23,501 --> 00:07:25,602 called magma contains dissolved 179 00:07:25,669 --> 00:07:29,506 gas. But as this magma rises, 180 00:07:29,573 --> 00:07:31,775 yhe pressure decreases. 181 00:07:31,842 --> 00:07:33,476 This drop in pressure means 182 00:07:33,511 --> 00:07:35,045 bubbles of the gas begin to 183 00:07:35,146 --> 00:07:37,313 appear just like opening 184 00:07:37,381 --> 00:07:39,215 a bottle of soda. 185 00:07:39,316 --> 00:07:41,117 If the magma is runny, these 186 00:07:41,218 --> 00:07:43,319 gases can safely escape. 187 00:07:43,387 --> 00:07:45,488 But in sticky, silica-rich Ring 188 00:07:45,556 --> 00:07:47,857 of Fire magma, the gases can get 189 00:07:47,925 --> 00:07:50,293 trapped, often with terrible 190 00:07:50,394 --> 00:07:52,762 consequences. 191 00:07:52,830 --> 00:07:54,097 >> It's like trying to 192 00:07:54,131 --> 00:07:55,465 have a bubble move through 193 00:07:55,566 --> 00:07:57,000 peanut butter. It won't happen 194 00:07:57,034 --> 00:07:58,635 quite so easily, so there's 195 00:07:58,669 --> 00:08:00,136 a lot of pressure that builds 196 00:08:00,204 --> 00:08:01,671 up. And once that pressure 197 00:08:01,772 --> 00:08:03,139 builds up, it reaches a point 198 00:08:03,207 --> 00:08:05,041 where it can't take all that 199 00:08:05,109 --> 00:08:08,111 pressure any more. 200 00:08:08,179 --> 00:08:10,947 >> The result--giant explosions 201 00:08:11,048 --> 00:08:12,482 caused by the catastrophic 202 00:08:12,550 --> 00:08:14,217 build-up of gas inside the 203 00:08:14,318 --> 00:08:17,954 molten rock. 204 00:08:18,022 --> 00:08:19,823 This is the reason Ring of Fire 205 00:08:19,857 --> 00:08:25,595 volcanoes can be so dangerous. 206 00:08:25,663 --> 00:08:26,930 But it's not usually the 207 00:08:27,031 --> 00:08:29,632 initial explosion that kills. 208 00:08:29,667 --> 00:08:32,936 It's what happens next. 209 00:08:33,003 --> 00:08:34,571 >> Those explosive eruptions 210 00:08:34,638 --> 00:08:36,306 can create plumes 211 00:08:36,407 --> 00:08:40,310 that go up for tens of miles. 212 00:08:40,377 --> 00:08:42,011 >> When these plumes run out of 213 00:08:42,113 --> 00:08:43,947 energy, they can collapse back 214 00:08:44,014 --> 00:08:45,648 down the sides of the volcano 215 00:08:45,683 --> 00:08:47,650 in a superheated avalanche of 216 00:08:47,718 --> 00:08:51,988 ash and gas. 217 00:08:52,022 --> 00:08:53,490 With temperatures of 1,300 218 00:08:53,557 --> 00:08:55,658 degrees fahrenheit and speeds 219 00:08:55,726 --> 00:08:58,294 over 100 miles per hour, these 220 00:08:58,395 --> 00:08:59,996 flows destroy everything in 221 00:09:00,030 --> 00:09:03,466 their path--a terrifying 222 00:09:03,567 --> 00:09:05,168 consequence of the explosive 223 00:09:05,202 --> 00:09:07,103 eruptions caused by gases 224 00:09:07,171 --> 00:09:09,405 building up inside thick lava. 225 00:09:13,177 --> 00:09:14,277 In the next stage of her 226 00:09:14,311 --> 00:09:16,379 investigation, Dr. Bull searches 227 00:09:16,447 --> 00:09:18,715 for clues as to how this sticky 228 00:09:18,749 --> 00:09:21,818 lava forms. On Augustine's lower 229 00:09:21,852 --> 00:09:23,553 slopes, she hunts for lava 230 00:09:23,654 --> 00:09:29,626 samples from inside the volcano. 231 00:09:29,660 --> 00:09:31,628 This giant block of solidified 232 00:09:31,662 --> 00:09:33,630 sticky lava was once molten 233 00:09:33,664 --> 00:09:37,100 magma, deep underground. 234 00:09:37,201 --> 00:09:38,801 It was blasted out here during 235 00:09:38,836 --> 00:09:41,104 an eruption. And it came with 236 00:09:41,205 --> 00:09:44,107 some intriguing evidence. 237 00:09:44,175 --> 00:09:45,341 >> So what I'm seeing in 238 00:09:45,409 --> 00:09:49,078 this rock is a lot of minerals 239 00:09:49,180 --> 00:09:51,181 and a little bit in some cases 240 00:09:51,248 --> 00:09:53,616 of hornblende. 241 00:09:53,717 --> 00:09:55,118 >> The presence of these 242 00:09:55,152 --> 00:09:56,519 hornblende crystals provides 243 00:09:56,620 --> 00:09:58,721 a crucial clue to how the magma 244 00:09:58,789 --> 00:10:00,423 formed. 245 00:10:00,524 --> 00:10:01,357 >> This is important in 246 00:10:01,425 --> 00:10:02,625 telling us something about 247 00:10:02,693 --> 00:10:04,427 magma conditions where the 248 00:10:04,495 --> 00:10:07,263 hornblende crystallized. 249 00:10:07,331 --> 00:10:08,798 Hornblende is a mineral that 250 00:10:08,866 --> 00:10:10,800 only forms in the presence of 251 00:10:10,868 --> 00:10:11,968 water. 252 00:10:12,036 --> 00:10:13,803 >> These hornblendes show water 253 00:10:13,904 --> 00:10:16,306 exists deep in the earth. 254 00:10:16,340 --> 00:10:18,241 Scientists suspect this water 255 00:10:18,342 --> 00:10:20,510 plays a crucial role in creating 256 00:10:20,611 --> 00:10:23,613 the magma that powers volcanoes. 257 00:10:23,714 --> 00:10:26,316 Deep underground, rocks are hot 258 00:10:26,350 --> 00:10:27,951 and semi-solid. 259 00:10:27,985 --> 00:10:29,319 It might seem that the presence 260 00:10:29,353 --> 00:10:31,988 of water would cool them down, 261 00:10:32,056 --> 00:10:34,490 but that's not what happens. 262 00:10:34,525 --> 00:10:36,793 This water, which is under huge 263 00:10:36,860 --> 00:10:38,962 pressure, alters the rocks' 264 00:10:39,029 --> 00:10:40,396 structure and causes them to 265 00:10:40,431 --> 00:10:44,334 melt, forming plumes of magma. 266 00:10:44,401 --> 00:10:46,069 This molten rock soars up to 267 00:10:46,136 --> 00:10:47,937 the surface, building giant 268 00:10:47,972 --> 00:10:49,906 volcanoes. 269 00:10:54,545 --> 00:10:56,312 Without water causing magma 270 00:10:56,380 --> 00:10:58,581 formation deep underground, 271 00:10:58,682 --> 00:11:00,450 these Ring of Fire volcanoes 272 00:11:00,484 --> 00:11:03,219 would simply not exist. 273 00:11:03,287 --> 00:11:04,854 >> A lot of this process 274 00:11:04,922 --> 00:11:06,022 we're still working on and we 275 00:11:06,090 --> 00:11:07,390 don't understand, but there's 276 00:11:07,491 --> 00:11:09,359 a fair amount of it that we do. 277 00:11:09,393 --> 00:11:10,293 And water has a very 278 00:11:10,394 --> 00:11:12,562 significant role in when and 279 00:11:12,663 --> 00:11:17,100 how rocks melt. 280 00:11:17,134 --> 00:11:18,768 >> The investigation into why 281 00:11:18,836 --> 00:11:21,037 the Ring of Fire is so dangerous 282 00:11:21,105 --> 00:11:22,472 has uncovered two important 283 00:11:22,573 --> 00:11:25,742 pieces of evidence. 284 00:11:25,843 --> 00:11:27,577 Blocky lava flows are 285 00:11:27,645 --> 00:11:28,945 evidence of thick, viscous 286 00:11:29,013 --> 00:11:31,314 magma which traps gases inside 287 00:11:31,382 --> 00:11:33,483 volcanoes, leading to explosive 288 00:11:33,584 --> 00:11:36,019 eruptions. 289 00:11:36,086 --> 00:11:37,553 And hornblende crystals reveal 290 00:11:37,655 --> 00:11:39,622 that water deep underground 291 00:11:39,657 --> 00:11:41,124 encourages the formation of the 292 00:11:41,191 --> 00:11:45,295 magma that powers the volcanoes. 293 00:11:45,362 --> 00:11:47,397 Next, the geology detectives 294 00:11:47,464 --> 00:11:49,299 figure out how this water gets 295 00:11:49,366 --> 00:11:51,634 underground and make 296 00:11:51,669 --> 00:11:53,369 a remarkable discovery-- 297 00:11:53,404 --> 00:11:54,837 The chemical signature of 298 00:11:54,905 --> 00:11:57,640 microscopic organisms inside 299 00:11:57,675 --> 00:12:00,376 the volcanoes. 300 00:12:02,786 --> 00:12:04,887 >> All around the Ring of Fire, 301 00:12:04,955 --> 00:12:07,089 explosive magma is forming deep 302 00:12:07,157 --> 00:12:12,895 underground, fuelled by water. 303 00:12:12,963 --> 00:12:14,530 Solving the mystery of where 304 00:12:14,631 --> 00:12:16,265 this water comes from is 305 00:12:16,333 --> 00:12:18,234 the key to how scientists will 306 00:12:18,268 --> 00:12:20,069 figure out why the Ring of Fire 307 00:12:20,136 --> 00:12:24,773 is so dangerous. 308 00:12:24,808 --> 00:12:26,408 The investigation now turns to 309 00:12:26,443 --> 00:12:29,545 Mount Lassen--an active volcano 310 00:12:29,613 --> 00:12:32,982 in Northern California. 311 00:12:33,083 --> 00:12:34,717 Surrounding the volcano are 312 00:12:34,818 --> 00:12:38,087 bubbling hot springs, boiling 313 00:12:38,154 --> 00:12:42,625 mud, and volcanic vents called 314 00:12:42,692 --> 00:12:44,727 fumaroles belching superheated 315 00:12:44,794 --> 00:12:48,330 steam and gas. 316 00:12:48,431 --> 00:12:49,865 All this thermal activity is 317 00:12:49,900 --> 00:12:51,500 driven by the immense heat 318 00:12:51,534 --> 00:12:53,168 rising from magma deep 319 00:12:53,236 --> 00:12:56,338 underground. 320 00:12:56,406 --> 00:12:57,973 By sampling the gas coming from 321 00:12:58,074 --> 00:13:00,042 these fumaroles, scientists 322 00:13:00,076 --> 00:13:01,410 hope to discer the source of 323 00:13:01,478 --> 00:13:02,945 the water which causes the 324 00:13:03,013 --> 00:13:06,682 magma to form. 325 00:13:06,750 --> 00:13:07,650 >> This device measures 326 00:13:07,684 --> 00:13:08,918 the temperature; the 327 00:13:08,952 --> 00:13:10,219 temperature of this fumarole is 328 00:13:10,220 --> 00:13:12,488 92.5 degrees "c", 329 00:13:12,555 --> 00:13:15,124 about 200 degrees fahrenheit. 330 00:13:15,225 --> 00:13:16,325 So just about at the boiling 331 00:13:16,393 --> 00:13:18,727 point for this elevation. 332 00:13:18,728 --> 00:13:19,862 And that's what we want for 333 00:13:19,930 --> 00:13:21,096 a good gas sample-- 334 00:13:21,131 --> 00:13:22,932 a good boiling fumarole. 335 00:13:22,999 --> 00:13:24,033 So you can see what's happening 336 00:13:24,134 --> 00:13:25,501 at the surface here--all this 337 00:13:25,568 --> 00:13:27,403 steam coming out of the ground. 338 00:13:27,504 --> 00:13:29,104 But it's the gases that are 339 00:13:29,139 --> 00:13:30,139 along with this steam that we 340 00:13:30,206 --> 00:13:31,840 look at closely. 341 00:13:31,942 --> 00:13:33,208 And the composition of those 342 00:13:33,276 --> 00:13:34,576 gases tell us about what's 343 00:13:34,678 --> 00:13:36,478 happening at various depths 344 00:13:36,546 --> 00:13:37,646 beneath the ground where we 345 00:13:37,681 --> 00:13:40,916 can't see. 346 00:13:40,984 --> 00:13:42,651 >> Tests on these gases, 347 00:13:42,719 --> 00:13:44,453 xollected from volcanoes all 348 00:13:44,521 --> 00:13:46,455 around the Pacific Ring of Fire, 349 00:13:46,556 --> 00:13:47,890 have revealed something 350 00:13:47,991 --> 00:13:52,361 surprising--the gases contain 351 00:13:52,462 --> 00:13:55,264 carbon-12, a type of carbon that 352 00:13:55,365 --> 00:13:58,634 comes from living organisms. 353 00:13:58,702 --> 00:14:00,703 The specific levels of c-12 354 00:14:00,737 --> 00:14:02,071 found here are the unique 355 00:14:02,172 --> 00:14:04,707 signature of tiny sea organisms 356 00:14:04,741 --> 00:14:08,344 called phytoplankton. 357 00:14:08,411 --> 00:14:10,179 Billions of phytoplankton live 358 00:14:10,280 --> 00:14:11,981 in the Ocean. 359 00:14:12,048 --> 00:14:13,615 As they grow, they absorb 360 00:14:13,717 --> 00:14:17,820 carbon-12 into their cells. 361 00:14:17,887 --> 00:14:19,955 When they die, they fall to the 362 00:14:19,990 --> 00:14:21,724 bottom, forming layers of 363 00:14:21,791 --> 00:14:22,992 sediment. 364 00:14:23,059 --> 00:14:25,094 In this way, their carbon-12 is 365 00:14:25,161 --> 00:14:28,630 transferred to the seafloor. 366 00:14:28,732 --> 00:14:30,532 Intriguingly, scientists have 367 00:14:30,600 --> 00:14:32,901 found this same carbon-12 368 00:14:32,969 --> 00:14:34,770 pouring out of volcanoes all 369 00:14:34,804 --> 00:14:38,907 around the Ring of Fire. 370 00:14:38,975 --> 00:14:40,542 >> Volcanoes of the Cascade 371 00:14:40,610 --> 00:14:41,810 Range have carbon dioxide 372 00:14:41,878 --> 00:14:44,413 that's very rich in carbon-12, 373 00:14:44,447 --> 00:14:45,347 And it's almost like 374 00:14:45,448 --> 00:14:48,517 you're cooking Oceanic sediments 375 00:14:48,551 --> 00:14:49,184 that are rich in 376 00:14:49,252 --> 00:14:51,887 phytoplankton down deep 377 00:14:51,955 --> 00:14:53,355 beneath these volcanoes to 378 00:14:53,423 --> 00:14:54,990 generate the carbon dioxide you 379 00:14:55,058 --> 00:14:58,961 see coming out the top. 380 00:14:58,995 --> 00:15:01,263 That links this carbon dioxide 381 00:15:01,331 --> 00:15:02,865 to organic sediments way 382 00:15:02,899 --> 00:15:04,700 offshore in the Ocean. 383 00:15:04,801 --> 00:15:05,801 The organic matter that was 384 00:15:05,902 --> 00:15:07,770 originally phytoplankton 385 00:15:07,804 --> 00:15:09,805 becomes carbon dioxide that we 386 00:15:09,839 --> 00:15:12,975 see at the surface. 387 00:15:13,043 --> 00:15:14,510 >> Seafloor sediments are 388 00:15:14,544 --> 00:15:17,146 getting into volcanoes. 389 00:15:17,180 --> 00:15:18,881 And these sediments contain 390 00:15:18,948 --> 00:15:21,316 seawater. 391 00:15:21,351 --> 00:15:23,152 This is the water that causes 392 00:15:23,219 --> 00:15:24,620 the rocks to melt below 393 00:15:24,721 --> 00:15:29,324 the volcanoes, forming magma. 394 00:15:29,359 --> 00:15:31,994 But a mystery remains. 395 00:15:32,062 --> 00:15:33,262 The magma plumes feeding 396 00:15:33,329 --> 00:15:35,064 the volcanoes lie sometimes 397 00:15:35,131 --> 00:15:36,532 hundreds of miles from the 398 00:15:36,599 --> 00:15:40,069 ocean. The scientists now have 399 00:15:40,170 --> 00:15:42,237 to figure out how the sediments 400 00:15:42,305 --> 00:15:44,239 loaded with seawater are moving 401 00:15:44,340 --> 00:15:51,346 so far inland. To find out, 402 00:15:51,448 --> 00:15:53,082 the investigation heads for 403 00:15:53,149 --> 00:15:57,786 Alaska's Chugach Mountains. 404 00:15:57,854 --> 00:15:59,855 The research here begins with 405 00:15:59,889 --> 00:16:04,860 an analysis of the local rocks. 406 00:16:04,861 --> 00:16:06,328 >> Oh, this is 407 00:16:06,429 --> 00:16:07,696 a really neat boulder that's 408 00:16:07,764 --> 00:16:09,164 right here. And what you can 409 00:16:09,232 --> 00:16:10,532 see in it is that there's this 410 00:16:10,533 --> 00:16:12,301 whole mixture of rock types. 411 00:16:12,335 --> 00:16:13,502 You can see that there's 412 00:16:13,536 --> 00:16:14,670 this black stuff which would 413 00:16:14,704 --> 00:16:16,071 originally have been mud. 414 00:16:16,139 --> 00:16:17,039 There's several different 415 00:16:17,073 --> 00:16:19,308 colors of kind of greenish 416 00:16:19,342 --> 00:16:20,309 rocks which would be kind of 417 00:16:20,343 --> 00:16:22,144 different flavors of volcanics. 418 00:16:22,212 --> 00:16:23,078 Oh, here it looks like 419 00:16:23,146 --> 00:16:24,713 there's limestone, 420 00:16:24,781 --> 00:16:26,215 and I'm gonna put some acid 421 00:16:26,249 --> 00:16:27,583 here. And if it fizzes, it's 422 00:16:27,617 --> 00:16:30,986 limestone. 423 00:16:31,054 --> 00:16:31,954 Yeah, sure enough that's what 424 00:16:32,055 --> 00:16:33,055 it is. 425 00:16:33,123 --> 00:16:33,889 And this would have formed 426 00:16:33,957 --> 00:16:35,424 in the Ocean. And so this is 427 00:16:35,525 --> 00:16:36,859 made up of the bodies of little 428 00:16:36,893 --> 00:16:38,427 critters that got incorporated 429 00:16:38,495 --> 00:16:39,695 into this rock, and now it's up 430 00:16:39,796 --> 00:16:43,065 here in the Chugach Mountains. 431 00:16:43,166 --> 00:16:44,566 >> The presence of jumbled 432 00:16:44,667 --> 00:16:46,835 oceanic rocks 20 miles from the 433 00:16:46,903 --> 00:16:48,837 sea is evidence that something 434 00:16:48,905 --> 00:16:50,272 remarkable is happening at 435 00:16:50,306 --> 00:16:54,042 the bottom of the Ocean. 436 00:16:54,110 --> 00:16:55,077 >> The fact that you have 437 00:16:55,111 --> 00:16:56,745 this mixture of rock types here 438 00:16:56,813 --> 00:16:57,846 is evidence for 439 00:16:57,914 --> 00:17:01,216 the seafloor moving. 440 00:17:01,284 --> 00:17:03,118 >> Geologists know that only 441 00:17:03,219 --> 00:17:04,553 an enormous process called 442 00:17:04,654 --> 00:17:06,488 subduction could shift these 443 00:17:06,556 --> 00:17:09,558 mixed Ocean sediments here. 444 00:17:09,659 --> 00:17:11,260 Subduction occurs when the 445 00:17:11,294 --> 00:17:14,096 seafloor moves and slides down 446 00:17:14,130 --> 00:17:16,732 under the land. 447 00:17:16,833 --> 00:17:18,300 As it descends, the top 448 00:17:18,401 --> 00:17:20,569 sediment layers are scraped off 449 00:17:20,670 --> 00:17:22,304 by the land like a snow plow 450 00:17:22,372 --> 00:17:24,439 scoops up snow. 451 00:17:24,474 --> 00:17:26,308 They're pushed up into a huge 452 00:17:26,376 --> 00:17:28,577 mound of mixed-up rocks. 453 00:17:28,645 --> 00:17:29,912 The Chugach Mountains were 454 00:17:30,013 --> 00:17:35,117 formed in this way. 455 00:17:35,185 --> 00:17:36,652 The seafloor, loaded with 456 00:17:36,719 --> 00:17:39,254 water, now continues down into 457 00:17:39,289 --> 00:17:42,391 the earth. 458 00:17:42,458 --> 00:17:44,760 This is how seawater gets deep 459 00:17:44,827 --> 00:17:46,562 underground where it creates 460 00:17:46,663 --> 00:17:48,363 the magma plumes that build 461 00:17:48,464 --> 00:17:50,199 the Ring of Fire's explosive 462 00:17:50,300 --> 00:17:54,203 volcanoes. 463 00:17:54,304 --> 00:17:55,571 >> Where we're at right now, 464 00:17:55,638 --> 00:17:57,005 the Pacific is subducting 465 00:17:57,106 --> 00:17:59,474 beneath us to the northwest 466 00:17:59,576 --> 00:18:00,842 at this northern part 467 00:18:00,910 --> 00:18:02,177 of the Ring of Fire. 468 00:18:02,212 --> 00:18:04,012 It's about 20 miles beneath our 469 00:18:04,113 --> 00:18:06,048 feet right here, but if we were 470 00:18:06,082 --> 00:18:07,349 to go off that way where the 471 00:18:07,450 --> 00:18:08,617 volcanoes are, it's about 472 00:18:08,718 --> 00:18:10,786 60 miles beneath our feet there. 473 00:18:10,853 --> 00:18:12,354 And so as it goes to the 474 00:18:12,422 --> 00:18:15,123 northwest, it subducts and then 475 00:18:15,158 --> 00:18:16,592 brings water and sediment into 476 00:18:16,626 --> 00:18:19,127 the earth that ends up causing 477 00:18:19,162 --> 00:18:20,796 melting in the mantle, and then 478 00:18:20,897 --> 00:18:23,232 that melt rises as magma to 479 00:18:23,266 --> 00:18:25,067 volcanoes. 480 00:18:25,134 --> 00:18:26,535 >> The investigation to discover 481 00:18:26,603 --> 00:18:28,704 how water is getting down below 482 00:18:28,805 --> 00:18:30,539 Ring of Fire volcanoes has 483 00:18:30,607 --> 00:18:34,076 turned up intriguing clues: 484 00:18:34,143 --> 00:18:35,510 Carbon-12 samples indicating 485 00:18:35,578 --> 00:18:36,979 fhat Ocean sediments are getting 486 00:18:37,080 --> 00:18:38,847 deep below the Ring of Fire's 487 00:18:38,881 --> 00:18:42,251 volcanoes and mixed rocks 488 00:18:42,318 --> 00:18:43,885 in the Chugach Mountains 489 00:18:43,953 --> 00:18:45,887 20 miles inland from the Ocean 490 00:18:45,989 --> 00:18:46,688 are evidence that 491 00:18:46,789 --> 00:18:48,257 the whole seafloor is on the 492 00:18:48,324 --> 00:18:50,425 move, sliding deep under the 493 00:18:50,526 --> 00:18:56,131 land. This process is the engine 494 00:18:56,165 --> 00:18:57,599 that powers the Ring of Fire's 495 00:18:57,700 --> 00:18:59,868 killer volcanoes. 496 00:18:59,936 --> 00:19:01,670 But deep underground, 497 00:19:01,738 --> 00:19:02,904 the Ring of Fire hides another 498 00:19:02,939 --> 00:19:06,675 even more deadly secret-- 499 00:19:06,743 --> 00:19:08,677 earthquakes that can destroy 500 00:19:08,745 --> 00:19:11,179 entire cities. 501 00:19:13,538 --> 00:19:15,906 >> The Ring of Fire--a lethal 502 00:19:16,173 --> 00:19:18,374 line of volcanoes-- 503 00:19:18,442 --> 00:19:21,010 75% of all the volcanoes on 504 00:19:21,111 --> 00:19:22,712 the planet. 505 00:19:22,746 --> 00:19:24,881 These fiery peaks encircling 506 00:19:24,915 --> 00:19:26,282 the Pacific Ocean are built by 507 00:19:26,350 --> 00:19:28,651 tremendous forces deep in the 508 00:19:28,719 --> 00:19:31,821 Earth. Eruptions here have taken 509 00:19:31,922 --> 00:19:33,556 many thousands of lives and 510 00:19:33,624 --> 00:19:35,358 destroyed billions of dollars 511 00:19:35,459 --> 00:19:36,893 of property. 512 00:19:36,927 --> 00:19:38,561 But an even bigger killer is 513 00:19:38,629 --> 00:19:40,930 present on the Ring of Fire... 514 00:19:44,835 --> 00:19:49,739 Earthquakes. 515 00:19:49,807 --> 00:19:52,108 90% of the world's quakes occur 516 00:19:52,176 --> 00:19:54,110 in this narrow band around the 517 00:19:54,178 --> 00:19:57,614 Pacific often with disastrous 518 00:19:57,648 --> 00:20:01,184 results. 519 00:20:01,252 --> 00:20:03,820 Sumatra, September 2009. 520 00:20:03,888 --> 00:20:05,288 A giant earthquake left more 521 00:20:05,356 --> 00:20:09,292 than a thousand people dead. 522 00:20:09,360 --> 00:20:12,362 Mexico, September 1985. 523 00:20:12,429 --> 00:20:13,997 More than 9,000 people were 524 00:20:14,064 --> 00:20:16,366 killed by a massive, magnitude 8 525 00:20:16,433 --> 00:20:20,169 quake that shook Mexico City. 526 00:20:20,271 --> 00:20:24,807 And Alaska, March 1964, 527 00:20:24,909 --> 00:20:26,276 North America's greatest-ever 528 00:20:26,377 --> 00:20:27,911 recorded earthquake, near 529 00:20:28,012 --> 00:20:32,015 Anchorage. 530 00:20:32,082 --> 00:20:34,183 This quake was so powerful, 531 00:20:34,251 --> 00:20:35,718 ground movements were observed 532 00:20:35,819 --> 00:20:41,057 4,000 miles away in Florida. 533 00:20:41,091 --> 00:20:42,892 Such awesome power drives 534 00:20:42,960 --> 00:20:44,827 scientists on to discover why 535 00:20:44,895 --> 00:20:46,896 these deadly quakes occur all 536 00:20:46,997 --> 00:20:50,233 around the Ring of Fire. 537 00:20:50,267 --> 00:20:51,634 The investigation moves to 538 00:20:51,735 --> 00:20:54,537 Prince William Sound, 36 miles 539 00:20:54,638 --> 00:20:55,738 from the epicenter of the 540 00:20:55,806 --> 00:21:00,376 1964 Alaskan disaster. 541 00:21:00,444 --> 00:21:02,245 >> We're at the northern edge 542 00:21:02,279 --> 00:21:03,713 of the Ring of Fire, 543 00:21:03,814 --> 00:21:04,647 and we're gonna be looking 544 00:21:04,715 --> 00:21:06,716 at evidence for how geologically 545 00:21:06,817 --> 00:21:11,354 active this area is today. 546 00:21:11,455 --> 00:21:12,088 >> Haeussler heads for 547 00:21:12,189 --> 00:21:13,890 Montague Island--a place that's 548 00:21:13,991 --> 00:21:15,425 permanently scarred by 549 00:21:15,459 --> 00:21:16,993 the powerful forces which shape 550 00:21:17,094 --> 00:21:20,263 this entire region. 551 00:21:20,331 --> 00:21:22,365 On land, he finds a rugged 552 00:21:22,433 --> 00:21:24,367 boulder-strewn shoreline. 553 00:21:28,272 --> 00:21:29,339 >> So you can see we're at 554 00:21:29,440 --> 00:21:30,073 the edge of the Ocean. 555 00:21:30,174 --> 00:21:31,274 We're in a high energy 556 00:21:31,342 --> 00:21:32,608 environment. There's boulders 557 00:21:32,643 --> 00:21:33,977 all over the place, and we're 558 00:21:34,078 --> 00:21:35,278 at the top of the beach. 559 00:21:35,346 --> 00:21:37,080 Waves have been crashing here 560 00:21:37,081 --> 00:21:38,414 and basically getting rid of the 561 00:21:38,449 --> 00:21:39,882 little tiny rocks, leaving only 562 00:21:39,950 --> 00:21:41,250 boulders behind. 563 00:21:41,352 --> 00:21:42,251 And then right here, you can see 564 00:21:42,353 --> 00:21:43,886 that these boulders are kind of 565 00:21:43,954 --> 00:21:45,588 lined up against each other 566 00:21:45,589 --> 00:21:47,223 like dominoes. And so it takes 567 00:21:47,257 --> 00:21:50,226 big waves to sort of flip these 568 00:21:50,227 --> 00:21:51,494 over and line them up kind of 569 00:21:51,495 --> 00:21:52,161 like dominoes 570 00:21:52,262 --> 00:21:54,263 Like that right here. 571 00:21:54,331 --> 00:21:56,332 >> But it's not this rocky beach 572 00:21:56,367 --> 00:21:58,001 that reveals how violent 573 00:21:58,068 --> 00:22:00,636 Ring of Fire quakes can be. 574 00:22:00,704 --> 00:22:03,406 The real evidence lies 1/4 mile 575 00:22:03,440 --> 00:22:08,077 inland. 576 00:22:08,145 --> 00:22:09,412 Haeussler hunts through 577 00:22:09,446 --> 00:22:11,814 the thick undergrowth. 578 00:22:15,719 --> 00:22:17,520 Hidden by the trees is a 579 00:22:17,588 --> 00:22:21,224 near-identical line of boulders. 580 00:22:21,258 --> 00:22:22,792 >> We've hiked in, 581 00:22:22,860 --> 00:22:24,494 thrashed through the alders, 582 00:22:24,528 --> 00:22:26,996 the Alaskan jungle up to here. 583 00:22:27,064 --> 00:22:28,965 We're probably 25 or 30 feet 584 00:22:29,066 --> 00:22:30,433 above sea level at this point, 585 00:22:30,501 --> 00:22:31,701 and what we have here is 586 00:22:31,769 --> 00:22:33,069 a beach. I mean, this is 587 00:22:33,170 --> 00:22:34,804 basically a perfectly preserved 588 00:22:34,905 --> 00:22:36,706 high energy beach environment 589 00:22:36,807 --> 00:22:37,540 like we were looking at down 590 00:22:37,608 --> 00:22:38,508 on the shoreline. 591 00:22:38,609 --> 00:22:39,976 And you can see here once again 592 00:22:40,077 --> 00:22:41,878 there is these big boulders 593 00:22:41,979 --> 00:22:43,079 that are sort of laid over 594 00:22:43,147 --> 00:22:45,348 in this domino-like fashion 595 00:22:45,449 --> 00:22:46,783 sort of pointing uphill 596 00:22:46,884 --> 00:22:48,051 as a result of this big wave 597 00:22:48,118 --> 00:22:49,952 energy, big waves pounding 598 00:22:50,020 --> 00:22:51,120 on the beach flipping the 599 00:22:51,188 --> 00:22:52,855 boulders over, pointing in 600 00:22:52,956 --> 00:22:57,360 the uphill direction. 601 00:22:57,394 --> 00:22:59,295 >> This inland raised shoreline 602 00:22:59,396 --> 00:23:01,464 runs for hundreds of yards 603 00:23:01,498 --> 00:23:06,569 parallel with the Ocean. 604 00:23:06,670 --> 00:23:09,005 It's a key piece of evidence. 605 00:23:09,039 --> 00:23:13,776 And it can only mean one thing-- 606 00:23:13,844 --> 00:23:15,845 the land itself must have 607 00:23:15,946 --> 00:23:16,946 recently risen up 608 00:23:17,014 --> 00:23:18,748 out of the Ocean, taking 609 00:23:18,849 --> 00:23:22,652 the entire shoreline with it. 610 00:23:22,719 --> 00:23:23,653 >> It means that there was 611 00:23:23,720 --> 00:23:25,188 an event that was essentially 612 00:23:25,222 --> 00:23:27,023 an instant in which this region 613 00:23:27,124 --> 00:23:29,859 was uplifted to this elevation 614 00:23:29,927 --> 00:23:31,494 and made this here. 615 00:23:31,562 --> 00:23:33,930 This has to have been 616 00:23:34,031 --> 00:23:37,300 a result of a big earthquake. 617 00:23:37,401 --> 00:23:40,303 Really cool. 618 00:23:40,404 --> 00:23:42,038 What we're looking at here is 619 00:23:42,106 --> 00:23:43,940 a result of the 1964 620 00:23:44,041 --> 00:23:45,308 great Alaska earthquake. 621 00:23:45,375 --> 00:23:46,476 Pretty much right here 622 00:23:46,577 --> 00:23:47,477 where we're at is where 623 00:23:47,578 --> 00:23:48,845 there was the largest uplift 624 00:23:48,846 --> 00:23:51,013 that occurred. 625 00:23:51,014 --> 00:23:52,482 The massive earthquake here not 626 00:23:52,549 --> 00:23:53,916 only lifted the land out 627 00:23:53,951 --> 00:23:55,485 of the sea, 628 00:23:55,586 --> 00:23:56,552 it also caused a wave of 629 00:23:56,587 --> 00:23:58,020 destruction, devastating 630 00:23:58,088 --> 00:23:59,922 nearby Anchorage. 631 00:24:00,023 --> 00:24:02,125 >> It was a magnitude 9.2. 632 00:24:02,192 --> 00:24:03,126 It was the second largest 633 00:24:03,193 --> 00:24:04,660 earthquake ever recorded on 634 00:24:04,728 --> 00:24:08,097 Earth. It was just enormous. It 635 00:24:08,132 --> 00:24:09,732 lasted 4 1/2 minutes 636 00:24:09,766 --> 00:24:12,468 of ground shaking. 637 00:24:12,536 --> 00:24:13,569 >> What happened throughout this 638 00:24:13,637 --> 00:24:14,737 region offers evidence of 639 00:24:14,771 --> 00:24:16,806 the type of quake that makes 640 00:24:16,907 --> 00:24:20,643 the Ring of Fire so dangerous. 641 00:24:20,744 --> 00:24:22,111 >> So we know from this kind of 642 00:24:22,179 --> 00:24:23,379 earthquake that occurred here in 643 00:24:23,380 --> 00:24:25,348 1964 that this was 644 00:24:25,349 --> 00:24:26,916 a thrust-type earthquake or 645 00:24:26,984 --> 00:24:28,851 even there was a fancy term, 646 00:24:28,919 --> 00:24:30,019 megathrust earthquake, because 647 00:24:30,120 --> 00:24:31,354 it was so big that occurred 648 00:24:31,388 --> 00:24:32,255 right here. 649 00:24:32,289 --> 00:24:33,823 And this is a result of the 650 00:24:33,891 --> 00:24:35,925 slippage of one piece of rock 651 00:24:35,993 --> 00:24:38,461 over another or one underneath 652 00:24:38,529 --> 00:24:40,563 the other. 653 00:24:40,664 --> 00:24:42,365 >> Megathrust quakes like this 654 00:24:42,399 --> 00:24:44,367 are the most powerful on earth 655 00:24:44,468 --> 00:24:45,568 and are one of the great 656 00:24:45,636 --> 00:24:48,471 dangers of the Ring of Fire. 657 00:24:48,572 --> 00:24:50,373 If they occur under the Ocean, 658 00:24:50,474 --> 00:24:52,475 they can generate killer waves 659 00:24:52,576 --> 00:24:56,479 called Tsunamis. 660 00:24:56,547 --> 00:24:57,980 The great Alaskan earthquake 661 00:24:58,015 --> 00:25:01,017 of 1964 caused a tsunami over 662 00:25:01,084 --> 00:25:03,819 200 feet high. 663 00:25:03,887 --> 00:25:05,821 Waves traveled over 1,700 664 00:25:05,889 --> 00:25:08,191 miles, claiming lives as far 665 00:25:08,292 --> 00:25:11,093 away as California. 666 00:25:11,195 --> 00:25:12,795 But this disaster was nothing 667 00:25:12,796 --> 00:25:13,896 compared to what happened 668 00:25:13,897 --> 00:25:16,098 compared to what happened in 2004. 669 00:25:20,003 --> 00:25:22,171 On December 26th, tragedy 670 00:25:22,206 --> 00:25:23,539 struck when an enormous 671 00:25:23,640 --> 00:25:24,774 underwater megathrust 672 00:25:24,841 --> 00:25:26,642 earthquake off the Asian coast 673 00:25:26,710 --> 00:25:29,812 generated monster waves. 674 00:25:29,846 --> 00:25:32,014 The coastlines of 14 countries 675 00:25:32,115 --> 00:25:33,983 were swamped, killing more than 676 00:25:34,017 --> 00:25:38,020 200,000 people. 677 00:25:38,088 --> 00:25:40,156 The vast scale of this disaster 678 00:25:40,190 --> 00:25:41,724 was a brutal indication of the 679 00:25:41,792 --> 00:25:46,295 power of megathrust earthquakes. 680 00:25:46,363 --> 00:25:47,930 And it's given urgency to 681 00:25:47,998 --> 00:25:49,699 finding out why these quakes 682 00:25:49,733 --> 00:25:51,067 happen all around 683 00:25:51,068 --> 00:25:53,836 happen all around the Ring of Fire. 684 00:26:00,544 --> 00:26:02,178 Once again, the Alaskan 685 00:26:02,246 --> 00:26:03,646 landscape is the perfect 686 00:26:03,747 --> 00:26:05,381 geological laboratory. 687 00:26:05,382 --> 00:26:06,549 >> So we're headed to 688 00:26:06,617 --> 00:26:08,884 a seismic station in 689 00:26:08,919 --> 00:26:10,653 south-central Alaska near 690 00:26:10,721 --> 00:26:15,992 the tip of the Kenai Peninsula. 691 00:26:15,993 --> 00:26:17,460 >> Millions of years of the Ring 692 00:26:17,527 --> 00:26:19,262 of Fire's volcanic activity and 693 00:26:19,363 --> 00:26:20,830 rippling earthquakes have given 694 00:26:20,897 --> 00:26:22,632 Alaska an incredibly rugged 695 00:26:22,733 --> 00:26:27,470 landscape. It's not easy to find 696 00:26:27,537 --> 00:26:32,108 a flat spot to land. 697 00:26:32,175 --> 00:26:35,144 >> It's clear on my side. 698 00:26:42,286 --> 00:26:43,919 >> High on the hillside lies 699 00:26:43,987 --> 00:26:45,921 West's seismic station, 700 00:26:45,989 --> 00:26:47,089 protected under the yellow 701 00:26:47,190 --> 00:26:49,325 cover from the elements and 702 00:26:49,359 --> 00:26:53,329 the local bears. 703 00:26:53,363 --> 00:26:55,998 >> So this is the vault 704 00:26:56,066 --> 00:26:56,966 where one of our seismic 705 00:26:57,000 --> 00:26:59,969 stations lives. This is one of 706 00:27:00,003 --> 00:27:01,737 the many seismic stations that 707 00:27:01,805 --> 00:27:05,374 dot the state of Alaska. 708 00:27:05,442 --> 00:27:07,009 >> Several thousand seismic 709 00:27:07,077 --> 00:27:08,978 stations like this exist, all 710 00:27:09,012 --> 00:27:10,513 the way from Alaska down to 711 00:27:10,547 --> 00:27:12,715 California. 712 00:27:12,816 --> 00:27:13,616 >> This whole system 713 00:27:13,717 --> 00:27:15,818 together monitors any kind of 714 00:27:15,886 --> 00:27:17,453 seismic activity, any sort of 715 00:27:17,521 --> 00:27:18,988 warthquakes throughout this 716 00:27:19,056 --> 00:27:20,156 whole area. 717 00:27:20,190 --> 00:27:21,824 It's part of a whole network on 718 00:27:21,892 --> 00:27:23,592 all of the volcanoes around 719 00:27:23,627 --> 00:27:25,728 here, on the mainland, and 720 00:27:25,796 --> 00:27:27,530 throughout this whole area. 721 00:27:27,631 --> 00:27:29,532 So the seismic data can be used 722 00:27:29,633 --> 00:27:31,634 not only to judge the severity 723 00:27:31,702 --> 00:27:32,435 of the earthquake 724 00:27:32,502 --> 00:27:34,970 or the magnitude, but also 725 00:27:35,005 --> 00:27:36,405 when taken across a number of 726 00:27:36,440 --> 00:27:37,873 stations to pinpoint the 727 00:27:37,941 --> 00:27:41,243 location of that earthquake. 728 00:27:41,311 --> 00:27:42,511 In Alaska, we're looking at 729 00:27:42,579 --> 00:27:44,046 about 1,500 earthquakes 730 00:27:44,147 --> 00:27:45,514 every month. 731 00:27:45,582 --> 00:27:47,016 And you take all of those 732 00:27:47,050 --> 00:27:48,384 together, and you start to see 733 00:27:48,418 --> 00:27:50,119 patterns. They map out 734 00:27:50,153 --> 00:27:52,421 a ribbon of earthquake activity 735 00:27:52,489 --> 00:27:53,589 that follows all along the 736 00:27:53,690 --> 00:27:55,958 coast. 737 00:27:56,026 --> 00:27:57,126 >> This ribbon of earthquake 738 00:27:57,194 --> 00:27:59,562 activity extends all around 739 00:27:59,596 --> 00:28:02,598 the Ring of Fire. 740 00:28:02,666 --> 00:28:04,500 But it is what scientists can 741 00:28:04,568 --> 00:28:06,502 see below the surface that is 742 00:28:06,603 --> 00:28:09,305 most revealing. 743 00:28:09,406 --> 00:28:10,206 >> If you look at it 744 00:28:10,307 --> 00:28:14,043 from the side, you see that 745 00:28:14,111 --> 00:28:15,211 actually the earthquakes that 746 00:28:15,312 --> 00:28:16,412 are happening close to the 747 00:28:16,480 --> 00:28:19,315 ocean tend to be shallow, but 748 00:28:19,416 --> 00:28:21,050 as you go inland, they're deeper 749 00:28:21,118 --> 00:28:22,485 and they create this dipping 750 00:28:22,586 --> 00:28:25,388 feature that starts out in 751 00:28:25,489 --> 00:28:27,223 the Ocean and then dips down 752 00:28:27,324 --> 00:28:31,227 beneath the continent. 753 00:28:31,294 --> 00:28:33,129 >> This giant dipping feature 754 00:28:33,230 --> 00:28:34,830 provides conclusive evidence 755 00:28:34,865 --> 00:28:36,031 for how the megathrust 756 00:28:36,099 --> 00:28:39,935 earthquakes are generated. 757 00:28:40,036 --> 00:28:41,303 The earthquake epicenters 758 00:28:41,371 --> 00:28:43,272 exactly follow the path taken 759 00:28:43,306 --> 00:28:45,107 by the seafloor as it moves 760 00:28:45,142 --> 00:28:48,010 down underneath the volcanoes. 761 00:28:48,044 --> 00:28:49,845 Earthquakes are triggered as 762 00:28:49,913 --> 00:28:51,680 the rocks slide past each other 763 00:28:51,748 --> 00:28:53,849 down into the earth. 764 00:28:53,950 --> 00:28:55,217 It is this subduction of the 765 00:28:55,318 --> 00:28:57,319 seafloor beneath the land which 766 00:28:57,387 --> 00:28:58,921 creates the Ring of Fire's 767 00:28:58,955 --> 00:29:00,923 lethal megathrust quakes 768 00:29:00,957 --> 00:29:02,858 and builds its explosive 769 00:29:02,926 --> 00:29:05,227 stratovolcanoes. 770 00:29:05,295 --> 00:29:06,595 >> So all of these 771 00:29:06,663 --> 00:29:07,830 observations--the volcanoes, 772 00:29:07,864 --> 00:29:09,832 the line of seismic activity, 773 00:29:09,933 --> 00:29:11,300 the big earthquakes at the 774 00:29:11,368 --> 00:29:12,835 interface--all of those are 775 00:29:12,936 --> 00:29:14,370 part of one system. 776 00:29:14,404 --> 00:29:15,671 They all tie together and are 777 00:29:15,772 --> 00:29:17,106 interrelated. 778 00:29:17,207 --> 00:29:18,908 >> The investigation into why 779 00:29:18,942 --> 00:29:20,376 the Ring of Fire is prone to 780 00:29:20,410 --> 00:29:22,278 such lethal earthquakes 781 00:29:22,279 --> 00:29:24,213 reveals... 782 00:29:24,214 --> 00:29:25,815 A raised shoreline-- 783 00:29:25,849 --> 00:29:26,949 evidence that the Ring of Fire 784 00:29:27,017 --> 00:29:28,484 suffers the most violent 785 00:29:28,585 --> 00:29:31,587 megathrust earthquakes. 786 00:29:31,655 --> 00:29:33,489 And seismic data shows that 787 00:29:33,557 --> 00:29:35,124 these killer quakes are caused 788 00:29:35,225 --> 00:29:36,826 by subduction, the movement of 789 00:29:36,860 --> 00:29:38,494 the seabed, which also builds 790 00:29:38,562 --> 00:29:40,129 the Ring of Fire's giant 791 00:29:40,197 --> 00:29:43,666 volcanoes. 792 00:29:43,733 --> 00:29:45,468 To discover exactly where 793 00:29:45,569 --> 00:29:47,002 this awesome process of 794 00:29:47,037 --> 00:29:48,404 subduction occurs, 795 00:29:48,472 --> 00:29:49,839 oceanographers search for the 796 00:29:49,940 --> 00:29:51,807 deepest and most inaccessible 797 00:29:51,842 --> 00:29:54,844 places on the entire planet. 798 00:29:58,355 --> 00:29:59,855 >> The journey to understand why 799 00:29:59,890 --> 00:30:01,624 the Pacific Ring of Fire is 800 00:30:01,691 --> 00:30:03,158 so volatile has revealed 801 00:30:03,260 --> 00:30:05,127 the critical role of subduction, 802 00:30:05,161 --> 00:30:06,862 which pushes the seabed deep 803 00:30:06,897 --> 00:30:10,099 down into the earth. 804 00:30:10,166 --> 00:30:11,700 In Alaska's Prince William 805 00:30:11,801 --> 00:30:14,069 Sound, investigators search for 806 00:30:14,170 --> 00:30:16,071 where the seafloor is vanishing 807 00:30:16,139 --> 00:30:20,042 below the land. 808 00:30:20,043 --> 00:30:22,611 >> There are ridges, 809 00:30:22,679 --> 00:30:26,515 outcrops, canyons, gullies, 810 00:30:26,616 --> 00:30:29,051 mountains underwater. 811 00:30:29,052 --> 00:30:31,053 And so the ability to make 812 00:30:31,154 --> 00:30:32,321 a continuous map of the 813 00:30:32,355 --> 00:30:33,789 seafloor, get a full picture of 814 00:30:33,890 --> 00:30:36,158 it gives you the ability to 815 00:30:36,226 --> 00:30:37,626 understand how the seafloor's 816 00:30:37,694 --> 00:30:39,495 put together and what it has to 817 00:30:39,596 --> 00:30:40,596 do with the way the Earth 818 00:30:40,697 --> 00:30:43,332 functions. 819 00:30:43,400 --> 00:30:45,167 >> Reynolds is using high-tech 820 00:30:45,235 --> 00:30:46,936 echo-sounding technology to 821 00:30:46,970 --> 00:30:48,871 monitor the exact depth of the 822 00:30:48,972 --> 00:30:53,576 seafloor. A sound wave is sent 823 00:30:53,610 --> 00:30:55,611 from beneath the ship. 824 00:30:55,679 --> 00:30:56,712 The time it takes to reach 825 00:30:56,780 --> 00:30:58,547 the seafloor and return gives 826 00:30:58,582 --> 00:31:03,018 an accurate reading of depth. 827 00:31:03,119 --> 00:31:04,920 Reynolds' research shows that 828 00:31:05,021 --> 00:31:06,922 all around the Alaskan coast, 829 00:31:06,990 --> 00:31:08,357 the seabed is relatively 830 00:31:08,391 --> 00:31:13,128 shallow. But farther out towards 831 00:31:13,196 --> 00:31:15,130 the open Ocean, the readings 832 00:31:15,198 --> 00:31:18,567 change dramatically. 833 00:31:18,668 --> 00:31:19,468 >> So in general 834 00:31:19,536 --> 00:31:20,302 around the world when 835 00:31:20,403 --> 00:31:21,937 you go out from land, you cross 836 00:31:22,005 --> 00:31:24,106 over a relatively flat shelf, 837 00:31:24,174 --> 00:31:25,441 down the slope, 838 00:31:25,475 --> 00:31:27,109 and into the deep Ocean basin 839 00:31:27,177 --> 00:31:28,944 which is very flat. 840 00:31:29,012 --> 00:31:31,113 But around the Ring of Fire as 841 00:31:31,181 --> 00:31:34,116 you go out from land across the 842 00:31:34,184 --> 00:31:35,985 shelf, down the slope, instead 843 00:31:36,019 --> 00:31:37,653 of going directly into a flat 844 00:31:37,721 --> 00:31:38,988 ocean basin, you go across 845 00:31:39,022 --> 00:31:41,123 a very deep trench. 846 00:31:41,191 --> 00:31:42,925 These trenches are the deepest 847 00:31:43,026 --> 00:31:45,894 areas on the planet, and the one 848 00:31:45,929 --> 00:31:46,895 around Alaska reaches 849 00:31:46,930 --> 00:31:52,568 approximately 21,000 feet. 850 00:31:52,636 --> 00:31:54,303 >> These giant features are 851 00:31:54,371 --> 00:31:56,672 called subduction trenches. 852 00:31:56,740 --> 00:31:58,307 The largest are deep enough to 853 00:31:58,375 --> 00:32:02,077 swallow all of Mount Everest. 854 00:32:02,112 --> 00:32:04,079 They mark the exact spot where 855 00:32:04,114 --> 00:32:06,081 the seafloor disappears down 856 00:32:06,149 --> 00:32:08,350 into the earth--the process 857 00:32:08,451 --> 00:32:09,718 that jolts the land in 858 00:32:09,786 --> 00:32:11,720 megathrust earthquakes and 859 00:32:11,788 --> 00:32:13,889 forms the volcanoes that make 860 00:32:13,957 --> 00:32:17,526 the Ring of Fire so dangerous. 861 00:32:17,627 --> 00:32:18,727 >> The Ring of Fire is named for 862 00:32:18,795 --> 00:32:21,063 these volcanoes that circle the 863 00:32:21,097 --> 00:32:23,365 Pacific Ocean, but offshore of 864 00:32:23,433 --> 00:32:24,700 the volcanoes--wherever you have 865 00:32:24,734 --> 00:32:26,235 a chain of volcanoes, you also 866 00:32:26,269 --> 00:32:28,003 have one of these deep Ocean 867 00:32:28,071 --> 00:32:29,905 trenches. 868 00:32:29,973 --> 00:32:31,540 >> The location and shape of the 869 00:32:31,641 --> 00:32:33,709 Ring of Fire is determined not 870 00:32:33,810 --> 00:32:36,111 by its famous volcanoes but by 871 00:32:36,179 --> 00:32:37,813 the position of these deep 872 00:32:37,847 --> 00:32:40,282 subduction trenches miles out 873 00:32:40,350 --> 00:32:42,718 in the Ocean. 874 00:32:42,752 --> 00:32:44,186 And by mapping the location 875 00:32:44,287 --> 00:32:45,554 of all the trenches in the 876 00:32:45,622 --> 00:32:47,823 Pacific Ocean, scientists have 877 00:32:47,924 --> 00:32:49,925 made a further, even more 878 00:32:49,993 --> 00:32:53,028 significant, discovery. 879 00:32:53,096 --> 00:32:54,530 High-tech imaging has made it 880 00:32:54,564 --> 00:32:56,065 possible for scientists to 881 00:32:56,099 --> 00:32:58,267 visualize the earth drained of 882 00:32:58,368 --> 00:32:59,735 its Oceans. 883 00:32:59,803 --> 00:33:01,370 This reveals that these deep 884 00:33:01,438 --> 00:33:03,372 trenches outline the edge of 885 00:33:03,440 --> 00:33:06,275 a giant rock slab, or plate, 886 00:33:06,342 --> 00:33:08,343 that makes up the entire floor 887 00:33:08,378 --> 00:33:11,246 of the Pacific Ocean. 888 00:33:11,281 --> 00:33:13,082 This huge Pacific plate is 889 00:33:13,116 --> 00:33:15,350 one of 14 plates which cover the 890 00:33:15,385 --> 00:33:20,089 entire surface of the planet. 891 00:33:20,156 --> 00:33:22,091 Subduction occurs where this 892 00:33:22,158 --> 00:33:23,459 plate rubs against one of its 893 00:33:23,526 --> 00:33:25,294 neighbors, producing the line 894 00:33:25,361 --> 00:33:27,262 of volcanoes which extends all 895 00:33:27,297 --> 00:33:31,100 around the Pacific. 896 00:33:31,167 --> 00:33:32,835 But the investigation isn't 897 00:33:32,902 --> 00:33:35,370 finished. Experts journey 898 00:33:35,472 --> 00:33:37,239 to Tiger Mountain in 899 00:33:37,273 --> 00:33:39,074 Washington State to figure out 900 00:33:39,142 --> 00:33:41,076 how such huge plates can be 901 00:33:41,144 --> 00:33:43,579 shifted against each other. 902 00:33:43,613 --> 00:33:45,581 >> The gps that you use to 903 00:33:45,615 --> 00:33:47,516 drive around can tell you where 904 00:33:47,584 --> 00:33:49,051 you're at on a city block or on 905 00:33:49,152 --> 00:33:50,753 a street to within a meter or 906 00:33:50,754 --> 00:33:52,020 so. But in geology, 907 00:33:52,055 --> 00:33:53,021 we're interested 908 00:33:53,056 --> 00:33:54,223 in centimeter to millimeter 909 00:33:54,257 --> 00:33:58,527 accuracy so that we can track 910 00:33:58,595 --> 00:34:00,763 the changing of the land. 911 00:34:00,764 --> 00:34:06,034 It's much more subtle. 912 00:34:06,069 --> 00:34:07,603 >> High on the mountainside, 913 00:34:07,670 --> 00:34:09,238 Flake has set up a gps marker 914 00:34:09,305 --> 00:34:11,507 point. 915 00:34:11,608 --> 00:34:12,674 >> Here we are on Tiger 916 00:34:12,776 --> 00:34:13,509 Mountain. 917 00:34:13,610 --> 00:34:14,877 This is our gps unit. 918 00:34:14,944 --> 00:34:16,512 What we have is these metal 919 00:34:16,613 --> 00:34:19,381 rods going into solid bedrock, 920 00:34:19,415 --> 00:34:20,382 cemented in so that there's 921 00:34:20,416 --> 00:34:21,517 no motion. 922 00:34:21,584 --> 00:34:23,886 This gps antenna allows us to 923 00:34:23,953 --> 00:34:26,021 measure point positions per day 924 00:34:26,055 --> 00:34:29,858 of where this spot is. 925 00:34:29,959 --> 00:34:31,693 >> A network of these gps 926 00:34:31,761 --> 00:34:33,929 antennas across North America 927 00:34:33,963 --> 00:34:35,130 provides evidence for the 928 00:34:35,231 --> 00:34:37,065 monumental forces which power 929 00:34:37,133 --> 00:34:38,700 the Ring of Fire. 930 00:34:38,768 --> 00:34:40,202 >> This is just 931 00:34:40,236 --> 00:34:41,236 a single antenna. There's 932 00:34:41,304 --> 00:34:42,471 hundreds all across the western 933 00:34:42,505 --> 00:34:43,872 United States to give us 934 00:34:43,973 --> 00:34:45,140 a better picture of what's going 935 00:34:45,208 --> 00:34:46,842 on with the ground surface. 936 00:34:46,876 --> 00:34:47,943 By combining all the data 937 00:34:48,044 --> 00:34:49,478 of these gps, we're able to see 938 00:34:49,512 --> 00:34:50,512 that North America 939 00:34:50,580 --> 00:34:54,316 is actually moving. 940 00:34:54,417 --> 00:34:56,018 >> The entire continent is 941 00:34:56,052 --> 00:34:57,653 moving westwards at about 942 00:34:57,687 --> 00:35:02,024 3 inches per year. 943 00:35:02,058 --> 00:35:03,292 This movement is possible 944 00:35:03,326 --> 00:35:04,860 because the earth's crust rides 945 00:35:04,928 --> 00:35:07,129 upon a hot, soft layer of rock 946 00:35:07,230 --> 00:35:11,233 called the mantle. 947 00:35:11,334 --> 00:35:12,768 >> Well, the mantle is so hot 948 00:35:12,836 --> 00:35:14,203 and at such a high pressure, 949 00:35:14,237 --> 00:35:15,304 and the temperature is hotter 950 00:35:15,405 --> 00:35:16,505 as you get towards the center 951 00:35:16,606 --> 00:35:18,874 of the earth, that's gonna want 952 00:35:18,942 --> 00:35:21,143 to move out and convect just 953 00:35:21,211 --> 00:35:22,778 like a boiling pot of water. 954 00:35:22,879 --> 00:35:24,046 And so it creates a convection 955 00:35:24,147 --> 00:35:26,515 current coming up to the surface 956 00:35:26,583 --> 00:35:27,482 which then drags along 957 00:35:27,517 --> 00:35:30,219 those plates on top. 958 00:35:30,286 --> 00:35:32,054 >> These phenomenal convection 959 00:35:32,121 --> 00:35:33,288 currents force the Pacific 960 00:35:33,323 --> 00:35:35,224 Plate into its neighbors, 961 00:35:35,325 --> 00:35:36,758 driving the process of 962 00:35:36,860 --> 00:35:40,662 subduction. 963 00:35:40,697 --> 00:35:41,396 >> As the plates get 964 00:35:41,464 --> 00:35:42,297 dragged by the mantle 965 00:35:42,398 --> 00:35:44,499 convection currents, they impede 966 00:35:44,601 --> 00:35:46,301 upon other plates. 967 00:35:46,402 --> 00:35:47,870 One has to give, so one dives 968 00:35:47,937 --> 00:35:49,571 down underneath another. 969 00:35:49,639 --> 00:35:51,206 And then the trapped water from 970 00:35:51,241 --> 00:35:53,775 its Ocean sediment escapes and 971 00:35:53,843 --> 00:35:55,911 melts the upper-lying mantle. 972 00:35:55,945 --> 00:35:58,413 And that creates hot magma that 973 00:35:58,481 --> 00:35:59,648 rises to the surface and 974 00:35:59,682 --> 00:36:00,949 creates the volcanoes that form 975 00:36:01,050 --> 00:36:03,752 around the Ring of Fire. 976 00:36:03,820 --> 00:36:04,953 >> The investigation into the 977 00:36:05,021 --> 00:36:06,455 forces that drive the Ring of 978 00:36:06,489 --> 00:36:09,725 Fire has now found 979 00:36:09,792 --> 00:36:11,193 subduction trenches that reveal 980 00:36:11,261 --> 00:36:12,728 the shape of the entire 981 00:36:12,795 --> 00:36:15,097 Pacific Plate 982 00:36:15,198 --> 00:36:18,333 And gps data providing evidence 983 00:36:18,368 --> 00:36:19,534 for the convection currents 984 00:36:19,636 --> 00:36:21,637 which force this giant plate 985 00:36:21,738 --> 00:36:25,173 against its neighbors. 986 00:36:25,241 --> 00:36:27,175 It is this movement of the 987 00:36:27,243 --> 00:36:28,644 entire Pacific plate and the 988 00:36:28,711 --> 00:36:30,178 resulting subduction of the 989 00:36:30,280 --> 00:36:32,714 seafloor down the trenches that 990 00:36:32,782 --> 00:36:33,815 shapes and builds 991 00:36:33,883 --> 00:36:37,986 the Ring of Fire. 992 00:36:38,087 --> 00:36:41,356 But one final mystery remains. 993 00:36:41,424 --> 00:36:43,558 Vast sections of the seafloor 994 00:36:43,626 --> 00:36:46,628 are constantly being destroyed. 995 00:36:46,696 --> 00:36:48,463 But despite millions of years 996 00:36:48,531 --> 00:36:49,865 of subduction down these 997 00:36:49,933 --> 00:36:52,401 trenches, the planet's seafloors 998 00:36:52,502 --> 00:36:54,403 have never been eradicated. 999 00:36:54,504 --> 00:36:55,203 The geology detectives 1000 00:36:55,204 --> 00:36:58,304 can now reveal why. 1001 00:37:00,467 --> 00:37:02,402 >> All around the Ring of Fire, 1002 00:37:02,503 --> 00:37:04,137 enormous volcanoes dot 1003 00:37:04,238 --> 00:37:06,139 a landscape warped by violent 1004 00:37:06,206 --> 00:37:09,776 earthquakes. Offshore, 1005 00:37:09,877 --> 00:37:11,578 the seafloor is swallowed down 1006 00:37:11,612 --> 00:37:14,881 giant subduction trenches. 1007 00:37:14,949 --> 00:37:16,583 But despite millions of years 1008 00:37:16,684 --> 00:37:18,318 of subduction, the area of 1009 00:37:18,419 --> 00:37:20,119 seafloor remains roughly the 1010 00:37:20,154 --> 00:37:22,388 same. 1011 00:37:22,423 --> 00:37:24,023 Geologists could only assume 1012 00:37:24,058 --> 00:37:26,759 one thing: Somewhere far out 1013 00:37:26,860 --> 00:37:28,928 in the Ocean, volcanic activity 1014 00:37:28,963 --> 00:37:31,064 must be creating new seafloor 1015 00:37:31,131 --> 00:37:33,499 rocks, replacing those destroyed 1016 00:37:33,601 --> 00:37:37,403 here during subduction. 1017 00:37:37,471 --> 00:37:40,039 Beginning in 1977, a series of 1018 00:37:40,140 --> 00:37:41,608 expeditions set out to 1019 00:37:41,675 --> 00:37:45,578 investigate where this occurred. 1020 00:37:45,646 --> 00:37:47,313 Scientists realized that if 1021 00:37:47,414 --> 00:37:48,748 volcanic activity was 1022 00:37:48,782 --> 00:37:51,217 constructing new seabed, the 1023 00:37:51,285 --> 00:37:52,418 surrounding water should be 1024 00:37:52,486 --> 00:37:56,055 warm. The Alvin Submersible was 1025 00:37:56,123 --> 00:37:57,757 equipped with high-tech sensors 1026 00:37:57,825 --> 00:37:59,492 to discover where this warm 1027 00:37:59,560 --> 00:38:03,763 water existed. 1028 00:38:03,831 --> 00:38:05,598 To begin with, the crew searched 1029 00:38:05,666 --> 00:38:10,770 the seafloor without any luck. 1030 00:38:10,838 --> 00:38:15,241 But then they hit the jackpot-- 1031 00:38:15,309 --> 00:38:16,943 A column of rock pumping out 1032 00:38:17,044 --> 00:38:20,279 superheated water. 1033 00:38:20,314 --> 00:38:25,118 This is a black smoker. 1034 00:38:25,185 --> 00:38:25,952 Measurements of the water 1035 00:38:26,053 --> 00:38:27,387 around these features have 1036 00:38:27,488 --> 00:38:29,122 found temperatures in excess of 1037 00:38:29,189 --> 00:38:33,760 750 degrees fahrenheit. 1038 00:38:33,861 --> 00:38:36,029 This heat comes from magma 1039 00:38:36,130 --> 00:38:37,463 welling up from inside the 1040 00:38:37,498 --> 00:38:41,367 Planet. It was a discovery that 1041 00:38:41,402 --> 00:38:42,468 provided the evidence 1042 00:38:42,503 --> 00:38:44,470 the scientists needed. 1043 00:38:44,505 --> 00:38:46,272 These volcanic marvels mark 1044 00:38:46,306 --> 00:38:48,474 the location of giant features 1045 00:38:48,509 --> 00:38:52,645 called mid-Ocean ridges. 1046 00:38:52,680 --> 00:38:54,113 At these ridges on the bottom 1047 00:38:54,214 --> 00:38:55,748 of the Ocean, powerful 1048 00:38:55,849 --> 00:38:56,916 convection currents in the 1049 00:38:56,950 --> 00:38:59,652 mantle separate Earth's plates, 1050 00:38:59,687 --> 00:39:01,320 allowing lava to spill out 1051 00:39:01,388 --> 00:39:03,556 onto the seabed. 1052 00:39:03,557 --> 00:39:04,857 >> New Oceanic crust is 1053 00:39:04,925 --> 00:39:06,259 constantly being formed out in 1054 00:39:06,360 --> 00:39:07,894 the mid-Ocean ridges. 1055 00:39:07,995 --> 00:39:09,362 That crust moves away from those 1056 00:39:09,430 --> 00:39:10,630 ridges towards the edge 1057 00:39:10,698 --> 00:39:11,330 of the continents, 1058 00:39:11,365 --> 00:39:13,533 where we're located now. 1059 00:39:13,534 --> 00:39:15,368 >> In this way, the seafloor is 1060 00:39:15,469 --> 00:39:17,437 constantly renewed, replacing 1061 00:39:17,471 --> 00:39:19,539 material destroyed by subduction 1062 00:39:19,640 --> 00:39:22,241 at the edges of the Ocean. 1063 00:39:22,276 --> 00:39:24,377 These mid-Ocean ridges exist 1064 00:39:24,478 --> 00:39:25,978 at the bottom of every Ocean on 1065 00:39:26,013 --> 00:39:27,246 Earth. 1066 00:39:27,281 --> 00:39:28,648 They provide a never-ending 1067 00:39:28,716 --> 00:39:31,184 supply of new rock, keeping 1068 00:39:31,251 --> 00:39:33,619 alive the entire plate tectonic 1069 00:39:33,687 --> 00:39:34,454 cycle. 1070 00:39:34,521 --> 00:39:35,254 >> Well, this is 1071 00:39:35,322 --> 00:39:37,356 a planetary scale process, 1072 00:39:37,357 --> 00:39:40,727 this is the planet itself 1073 00:39:40,828 --> 00:39:43,796 circulating. And the rock and 1074 00:39:43,897 --> 00:39:45,598 the magma from deep inside the 1075 00:39:45,632 --> 00:39:47,366 Earth welling up to the surface 1076 00:39:47,434 --> 00:39:49,068 forming this crust. 1077 00:39:49,069 --> 00:39:51,070 And then that crust dives back 1078 00:39:51,171 --> 00:39:52,371 down into the earth 1079 00:39:52,439 --> 00:39:53,773 at the subduction zones, 1080 00:39:53,807 --> 00:39:56,509 at the trenches. And it's mixed 1081 00:39:56,543 --> 00:40:00,613 back into the solid earth. 1082 00:40:00,681 --> 00:40:02,615 >> So great is the power driving 1083 00:40:02,683 --> 00:40:04,250 this system that experts see 1084 00:40:04,351 --> 00:40:06,085 no end to the constant movement 1085 00:40:06,186 --> 00:40:09,722 of plates around the planet. 1086 00:40:09,790 --> 00:40:10,957 >> The forces involved 1087 00:40:10,991 --> 00:40:13,059 with plate tectonics caused by 1088 00:40:13,060 --> 00:40:14,694 the heating from the inner core 1089 00:40:14,728 --> 00:40:17,630 of the Earth is so astronomical 1090 00:40:17,698 --> 00:40:18,431 that there is 1091 00:40:18,499 --> 00:40:20,366 nothing that will stop it. 1092 00:40:20,434 --> 00:40:21,067 >> It seems like 1093 00:40:21,135 --> 00:40:22,769 the Ring of Fire will go on for 1094 00:40:22,803 --> 00:40:23,703 some period of time. 1095 00:40:23,771 --> 00:40:25,071 It looks as if we've been 1096 00:40:25,172 --> 00:40:26,405 having subduction here 1097 00:40:26,440 --> 00:40:27,974 underneath southern Alaska on 1098 00:40:28,075 --> 00:40:29,342 the order of 200 million years. 1099 00:40:29,343 --> 00:40:32,245 And it looks like-- 1100 00:40:32,346 --> 00:40:33,379 There's no evidence that it's 1101 00:40:33,413 --> 00:40:36,048 gonna stop any time soon. 1102 00:40:36,116 --> 00:40:37,416 >> But over the coming billions 1103 00:40:37,451 --> 00:40:39,585 of years, the ongoing movement 1104 00:40:39,653 --> 00:40:41,487 of plates will redraw the map 1105 00:40:41,588 --> 00:40:43,422 of the world. 1106 00:40:43,490 --> 00:40:44,490 >> The Pacific Plate is 1107 00:40:44,525 --> 00:40:47,026 moving, and things on it ride 1108 00:40:47,127 --> 00:40:48,761 with the plates that 1109 00:40:48,862 --> 00:40:50,496 are being subducted. So for 1110 00:40:50,597 --> 00:40:52,298 example, the Hawaiian Islands 1111 00:40:52,399 --> 00:40:54,867 are moving up here to Alaska, 1112 00:40:54,935 --> 00:40:56,502 parts of California are moving 1113 00:40:56,570 --> 00:40:58,404 up here to Alaska, 1114 00:40:58,472 --> 00:40:59,939 Baja California is moving north 1115 00:41:00,040 --> 00:41:01,741 here to Alaska. So apparently 1116 00:41:01,775 --> 00:41:03,676 Alaska's a popular place to be. 1117 00:41:03,744 --> 00:41:04,944 It'll be the resting-place of 1118 00:41:05,045 --> 00:41:08,581 all these things. 1119 00:41:08,649 --> 00:41:10,116 >> So the map of the Pacific 1120 00:41:10,217 --> 00:41:12,585 will slowly change driven by 1121 00:41:12,653 --> 00:41:16,122 the immense force of subduction. 1122 00:41:16,190 --> 00:41:18,391 This is the real story of the 1123 00:41:18,458 --> 00:41:22,195 Ring of Fire. 1124 00:41:22,229 --> 00:41:24,497 Subduction creates the magma 1125 00:41:24,565 --> 00:41:26,199 plumes which build the region's 1126 00:41:26,233 --> 00:41:29,502 explosive volcanoes. 1127 00:41:29,570 --> 00:41:31,671 Subduction powers the violent 1128 00:41:31,772 --> 00:41:33,506 megathrust earthquakes that 1129 00:41:33,574 --> 00:41:35,408 shake the region, leveling 1130 00:41:35,475 --> 00:41:37,577 whole cities in seconds 1131 00:41:37,678 --> 00:41:40,213 and causing killer tsunamis. 1132 00:41:44,117 --> 00:41:45,585 >> This process of subduction 1133 00:41:45,652 --> 00:41:46,485 just releases 1134 00:41:46,587 --> 00:41:48,120 an enormous amount of energy 1135 00:41:48,222 --> 00:41:50,356 through both earthquakes, 1136 00:41:50,390 --> 00:41:51,190 through building these 1137 00:41:51,225 --> 00:41:52,859 mountains, through volcanoes. 1138 00:41:52,926 --> 00:41:55,561 It's just really inconceivably 1139 00:41:55,629 --> 00:41:57,663 huge. 1140 00:41:57,764 --> 00:41:59,465 >> This is what makes the Ring 1141 00:41:59,499 --> 00:42:01,300 Of Fire the most geologically 1142 00:42:01,368 --> 00:42:03,769 active and most deadly place 1143 00:42:03,837 --> 00:42:05,738 on the entire planet. 1144 00:42:05,772 --> 00:42:06,572 >> And you see the whole 1145 00:42:06,640 --> 00:42:07,840 picture of creation 1146 00:42:07,941 --> 00:42:10,309 and destruction of a plate in 1147 00:42:10,377 --> 00:42:12,111 the Pacific Ocean. And the Ring 1148 00:42:12,179 --> 00:42:15,181 Of Fire is the boundary of that 1149 00:42:15,215 --> 00:42:16,816 cycle, and it's the place where 1150 00:42:16,850 --> 00:42:17,750 all the destruction is 1151 00:42:17,851 --> 00:42:20,186 happening. 1152 00:42:20,220 --> 00:42:21,821 >> Geology detectives have now 1153 00:42:21,855 --> 00:42:23,389 pieced together the evidence 1154 00:42:23,457 --> 00:42:25,091 for what makes the Ring of Fire 1155 00:42:25,125 --> 00:42:27,660 so dangerous, and discovered 1156 00:42:27,761 --> 00:42:32,098 what powers it. 1157 00:42:32,199 --> 00:42:33,766 Violent eruptions of explosive 1158 00:42:33,834 --> 00:42:35,668 blocky lava build the Ring of 1159 00:42:35,736 --> 00:42:39,472 Fire's famous volcanoes. 1160 00:42:39,573 --> 00:42:41,307 Mixed rocks from the seafloor 1161 00:42:41,375 --> 00:42:43,442 found miles inland are evidence 1162 00:42:43,477 --> 00:42:44,844 for the process of subduction 1163 00:42:44,945 --> 00:42:48,915 that builds the volcanoes. 1164 00:42:48,949 --> 00:42:50,650 Raised shorelines are evidence 1165 00:42:50,717 --> 00:42:52,118 for giant megathrust 1166 00:42:52,219 --> 00:42:54,086 earthquakes caused deep 1167 00:42:54,121 --> 00:42:57,990 underground by subduction. 1168 00:42:58,025 --> 00:43:00,393 And gps plots provide evidence 1169 00:43:00,460 --> 00:43:01,661 for the immense convection 1170 00:43:01,762 --> 00:43:03,262 currents deep in the earth 1171 00:43:03,297 --> 00:43:06,265 which drive the entire system. 1172 00:43:10,470 --> 00:43:12,838 These giant forces have built 1173 00:43:12,906 --> 00:43:15,942 the Ring of Fire. 1174 00:43:16,009 --> 00:43:17,276 >> The energy that drives 1175 00:43:17,344 --> 00:43:19,211 rhis whole convective system 1176 00:43:19,279 --> 00:43:22,014 is really without parallel 1177 00:43:22,082 --> 00:43:22,982 on the earth. There's 1178 00:43:23,016 --> 00:43:24,083 nothing else that we can 1179 00:43:24,117 --> 00:43:25,484 compare it to as far as the 1180 00:43:25,552 --> 00:43:27,186 amount of energy and the force 1181 00:43:27,287 --> 00:43:28,287 that moves the continents 1182 00:43:28,388 --> 00:43:30,656 around, compresses them against 1183 00:43:30,757 --> 00:43:32,658 one another, drags one down 1184 00:43:32,726 --> 00:43:34,026 beneath the other. 1185 00:43:34,094 --> 00:43:36,395 Really just awesome forces. 1186 00:43:36,396 --> 00:43:39,365 >> These forces are unstoppable. 1187 00:43:39,433 --> 00:43:40,566 And while the shape of the 1188 00:43:40,634 --> 00:43:43,202 Pacific will slowly change, for 1189 00:43:43,270 --> 00:43:45,371 millions of years to come, 1190 00:43:45,439 --> 00:43:46,739 explosive volcanoes will 1191 00:43:46,840 --> 00:43:52,178 continue to line its shores-- 1192 00:43:52,279 --> 00:43:54,180 Dynamic proof that the earth 1193 00:43:54,281 --> 00:43:55,881 is never at rest. 1194 00:43:55,916 --> 00:44:00,383 -- Sync, corrected by elderman -- -- for MY-SUBS.com ---