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These are the user uploaded subtitles that are being translated: 1 00:00:03,671 --> 00:00:08,107 Our planet is capable of unleashing extreme chaos. 2 00:00:08,142 --> 00:00:15,414 Volcanoes, earthquakes, hurricanes, and floods 3 00:00:15,449 --> 00:00:17,983 can cause untold devastation. 4 00:00:19,353 --> 00:00:20,719 We may think we've seen 5 00:00:20,755 --> 00:00:23,956 the worst Mother Nature can throw at us, 6 00:00:23,991 --> 00:00:27,760 but scientists struggling to understand these disasters 7 00:00:27,795 --> 00:00:30,496 are discovering evidence that even more extreme events 8 00:00:30,531 --> 00:00:33,298 have struck in the past. 9 00:00:33,334 --> 00:00:35,834 JEAN CHRISTOPHE KOMOROWSKI: So this is about 13 times 10 00:00:35,870 --> 00:00:38,203 more powerful than the Pompeii eruption. 11 00:00:38,239 --> 00:00:40,372 NARRATOR: They're uncovering clues 12 00:00:40,408 --> 00:00:44,276 that the worst catastrophes in history 13 00:00:44,311 --> 00:00:46,845 could strike again. 14 00:00:50,918 --> 00:00:52,651 Nearly 1,000 years ago, 15 00:00:52,686 --> 00:00:55,320 a disaster shook the world. 16 00:00:55,356 --> 00:00:57,556 KOMOROWSKI: This is one of the largest eruptions 17 00:00:57,591 --> 00:00:59,391 in the last 10,000 years. 18 00:00:59,427 --> 00:01:02,795 NARRATOR: A volcano so powerful 19 00:01:02,830 --> 00:01:05,964 it chilled the entire planet. 20 00:01:06,000 --> 00:01:07,833 But where was it? 21 00:01:07,868 --> 00:01:09,435 No one knew the source of the eruption. 22 00:01:09,470 --> 00:01:15,607 NARRATOR: The clues are here, buried and hidden all around the world. 23 00:01:15,643 --> 00:01:17,609 Now, scientists come together 24 00:01:17,645 --> 00:01:22,047 to scour our volatile Earth, to solve the mystery 25 00:01:22,083 --> 00:01:24,850 of killer volcanoes. 26 00:01:27,955 --> 00:01:30,055 Right now, on NOVA. 27 00:01:40,801 --> 00:01:44,136 NARRATOR: Of all the forces of nature, 28 00:01:44,171 --> 00:01:46,538 volcanoes are among the most dangerous. 29 00:01:48,642 --> 00:01:49,975 They have the power 30 00:01:50,010 --> 00:01:56,214 to kill millions and disrupt the fabric of modern life. 31 00:01:56,250 --> 00:01:57,582 Volcanoes can have a global impact. 32 00:01:57,618 --> 00:02:01,420 NARRATOR: Today, there are more than 1,500 33 00:02:01,455 --> 00:02:04,389 active volcanoes on Earth. 34 00:02:04,425 --> 00:02:08,260 About 50 erupt every year. 35 00:02:08,295 --> 00:02:12,464 Many are well known, like Vesuvius in Italy, 36 00:02:12,499 --> 00:02:16,101 and Mount St. Helens in Washington State. 37 00:02:16,136 --> 00:02:18,837 But could there be other slumbering giants 38 00:02:18,872 --> 00:02:20,138 that we have never heard of? 39 00:02:20,174 --> 00:02:22,341 Volcanoes that were once 40 00:02:22,376 --> 00:02:25,444 even more powerful and destructive 41 00:02:25,479 --> 00:02:27,679 than today's monsters? 42 00:02:27,715 --> 00:02:31,049 That's what a series of clues is suggesting. 43 00:02:33,754 --> 00:02:36,021 Scientists working across the world 44 00:02:36,056 --> 00:02:40,258 have begun to find evidence of a cataclysmic event, 45 00:02:40,294 --> 00:02:43,228 a mysterious eruption that could have been 46 00:02:43,263 --> 00:02:46,898 one of the largest in human history. 47 00:02:49,169 --> 00:02:53,238 And the trail starts in a very unexpected place. 48 00:02:58,078 --> 00:03:01,079 Here, in the heart of London, 49 00:03:01,115 --> 00:03:04,983 archaeologists uncover a surprise. 50 00:03:11,158 --> 00:03:14,960 While excavating a medieval cemetery, 51 00:03:14,995 --> 00:03:18,363 they happened upon a series of mass graves 52 00:03:18,399 --> 00:03:20,866 on the edges of the burial ground. 53 00:03:22,169 --> 00:03:24,870 Over 4,000 men, women and children, 54 00:03:24,905 --> 00:03:28,106 packed into large pits. 55 00:03:29,877 --> 00:03:34,780 The cause of death was not obvious. 56 00:03:34,815 --> 00:03:37,282 So what killed so many people, 57 00:03:37,317 --> 00:03:41,286 and why were they all buried together? 58 00:03:41,321 --> 00:03:43,355 DON WALKER: When we find mass burial pits, 59 00:03:43,390 --> 00:03:46,258 we know that there's been a lot of people 60 00:03:46,293 --> 00:03:49,361 dying very quickly, and something has gone very wrong. 61 00:03:49,396 --> 00:03:53,331 NARRATOR: As a first step to identifying the killer, 62 00:03:53,367 --> 00:03:56,067 archaeologist Don Walker and his team conducted 63 00:03:56,103 --> 00:04:01,173 radiocarbon tests, to find out how long ago they died. 64 00:04:01,208 --> 00:04:04,409 The hope was that they could tie their deaths 65 00:04:04,445 --> 00:04:06,244 to some historical event. 66 00:04:06,280 --> 00:04:10,048 But what they found merely deepened the mystery. 67 00:04:12,286 --> 00:04:17,722 The victims all died around 1250 in the Common Era. 68 00:04:17,758 --> 00:04:19,257 That ruled out 69 00:04:19,293 --> 00:04:21,860 one of the most notorious mass killers of the past, 70 00:04:21,895 --> 00:04:25,063 the Black Death, which ravaged Europe 71 00:04:25,098 --> 00:04:29,601 about a century later, in 1348. 72 00:04:30,938 --> 00:04:33,271 So what could have caused this mass killing? 73 00:04:40,147 --> 00:04:43,148 Don Walker heads to the British Library 74 00:04:43,183 --> 00:04:46,318 to consult ancient historical records from the period. 75 00:04:49,857 --> 00:04:54,593 This manuscript is a history of England. 76 00:04:54,628 --> 00:04:58,864 Over 750 years old, it was written in Latin 77 00:04:58,899 --> 00:05:02,267 by a monk named Matthew Paris. 78 00:05:05,739 --> 00:05:07,005 Among these chronicles, 79 00:05:07,040 --> 00:05:08,907 one account stands out-- 80 00:05:08,942 --> 00:05:12,944 a description of bitterly cold weather around London 81 00:05:12,980 --> 00:05:15,881 in the spring and early summer of 1258 82 00:05:15,916 --> 00:05:18,049 that kills crops and livestock 83 00:05:18,085 --> 00:05:22,854 and leads to a deadly famine. 84 00:05:22,890 --> 00:05:25,657 WALKER: It says owing to the scarcity of wheat, 85 00:05:25,692 --> 00:05:28,226 a large number of poor people died, 86 00:05:28,262 --> 00:05:31,530 and dead bodies were found in all directions, 87 00:05:31,565 --> 00:05:32,964 swollen and livid. 88 00:05:34,535 --> 00:05:36,868 NARRATOR: Then Walker discovers 89 00:05:36,904 --> 00:05:39,137 a description that seems to match the discovery 90 00:05:39,172 --> 00:05:40,539 of the mass graves. 91 00:05:40,574 --> 00:05:43,808 When several corpses were found, 92 00:05:43,844 --> 00:05:46,411 large and spacious holes were dug in the cemeteries, 93 00:05:46,446 --> 00:05:49,447 and a great many bodies were laid in them together. 94 00:05:51,952 --> 00:05:55,487 And of course, as soon as I saw that, I got very excited, 95 00:05:55,522 --> 00:05:57,923 because it's exactly the kind of thing that we found 96 00:05:57,958 --> 00:06:00,425 at St. Mary Spital, where they were digging these huge pits. 97 00:06:04,831 --> 00:06:07,399 NARRATOR: According to this text, 98 00:06:07,434 --> 00:06:10,802 the famine killed over 15,000 people in London. 99 00:06:10,837 --> 00:06:14,339 That's 30% of the city's population at the time. 100 00:06:14,374 --> 00:06:16,575 WALKER: You're talking about something 101 00:06:16,610 --> 00:06:18,743 that was perhaps nearly as deadly as the Black Death. 102 00:06:20,113 --> 00:06:22,414 NARRATOR: And possibly as widespread too. 103 00:06:25,319 --> 00:06:27,886 Other sources reveal the far-reaching impact 104 00:06:27,921 --> 00:06:32,090 of the extreme weather and its disastrous effect on crops. 105 00:06:34,828 --> 00:06:38,229 CLIVE OPPENHEIMER: There are various records from this period-- 106 00:06:38,265 --> 00:06:40,966 1258, 1259, 1260, 107 00:06:41,001 --> 00:06:43,668 in various parts of Europe and as far as Japan, 108 00:06:43,704 --> 00:06:46,838 that do attest to extreme impacts 109 00:06:46,873 --> 00:06:49,240 in terms of famine, in particular. 110 00:06:51,845 --> 00:06:53,645 NARRATOR: Something devastating 111 00:06:53,680 --> 00:06:56,448 was plunging much of the Northern Hemisphere 112 00:06:56,483 --> 00:06:58,149 into a pattern of bitter winters 113 00:06:58,185 --> 00:07:01,987 and summers blighted by torrential rain. 114 00:07:02,022 --> 00:07:03,722 We thought perhaps this was something to do 115 00:07:03,757 --> 00:07:05,123 with some catastrophic event. 116 00:07:07,794 --> 00:07:09,694 NARRATOR: Only one type of natural disaster 117 00:07:09,730 --> 00:07:13,698 could have such a widespread impact on the climate-- 118 00:07:13,734 --> 00:07:16,501 a massive volcanic eruption. 119 00:07:18,138 --> 00:07:20,639 But which volcano was the culprit? 120 00:07:24,211 --> 00:07:27,178 The closest volcanoes are a thousand miles away in Iceland. 121 00:07:30,917 --> 00:07:35,453 In 2010, when a volcano known as Eyja erupted, 122 00:07:35,489 --> 00:07:37,389 it sent an ash cloud over Europe 123 00:07:37,424 --> 00:07:40,458 that disrupted air travel for weeks, 124 00:07:40,494 --> 00:07:43,028 stranding people all over the world. 125 00:07:45,399 --> 00:07:50,068 And historical records reveal that in 1783, 126 00:07:50,103 --> 00:07:52,303 eruptions from the Laki volcano 127 00:07:52,339 --> 00:07:55,807 caused mass deaths across Europe. 128 00:07:55,842 --> 00:07:58,943 It seems like an Icelandic volcano 129 00:07:58,979 --> 00:08:02,981 could be to blame for the mysterious 13th century event, 130 00:08:03,016 --> 00:08:06,384 but Walker came across another possibility. 131 00:08:06,420 --> 00:08:10,188 He became intrigued by one of the most massive eruptions 132 00:08:10,223 --> 00:08:11,456 in recorded history, 133 00:08:11,491 --> 00:08:16,461 even though it occurred just 200 years ago 134 00:08:16,496 --> 00:08:19,998 and was located much farther away-- 135 00:08:20,033 --> 00:08:24,369 Mount Tambora in Indonesia. 136 00:08:26,573 --> 00:08:29,941 In April 1815, eyewitness accounts record 137 00:08:29,976 --> 00:08:33,278 that Mount Tambora erupted explosively. 138 00:08:35,315 --> 00:08:37,782 KOMOROWSKI: And this is one of the largest eruptions 139 00:08:37,818 --> 00:08:39,818 of the last 10,000 years. 140 00:08:42,255 --> 00:08:45,457 NARRATOR: It's estimated over 60,000 people died 141 00:08:45,492 --> 00:08:48,193 in the shadow of this volcano. 142 00:08:49,730 --> 00:08:53,298 But the eruption had an even more far-reaching impact. 143 00:08:53,333 --> 00:08:57,702 In northern Europe and North America, 144 00:08:57,738 --> 00:09:01,840 the year after the eruption, 1816, is known as 145 00:09:01,875 --> 00:09:04,642 the year without a summer. 146 00:09:04,678 --> 00:09:08,012 In New York State, it snowed in June. 147 00:09:08,048 --> 00:09:14,319 In Europe, cold weather led to the worst famine for a century. 148 00:09:14,354 --> 00:09:16,387 The climate change 149 00:09:16,423 --> 00:09:18,690 caused agricultural failures, poor harvests, 150 00:09:18,725 --> 00:09:21,292 it pushed up grain prices, 151 00:09:21,328 --> 00:09:23,161 with many people perishing from malnourishment. 152 00:09:25,532 --> 00:09:28,199 NARRATOR: So perhaps another powerful eruption 153 00:09:28,235 --> 00:09:34,706 could have caused the year without a summer in 1258. 154 00:09:34,741 --> 00:09:37,442 We began to think that perhaps this might be something to do 155 00:09:37,477 --> 00:09:39,544 with what had happened back in the 13th century. 156 00:09:39,579 --> 00:09:41,646 Perhaps this was why the people starved. 157 00:09:41,681 --> 00:09:44,449 NARRATOR: But to pinpoint the location 158 00:09:44,484 --> 00:09:47,318 of the mysterious volcano, they needed to know more 159 00:09:47,354 --> 00:09:49,387 about its size and type of eruption. 160 00:09:51,525 --> 00:09:53,758 They look at one of the largest volcanic events 161 00:09:53,794 --> 00:09:55,026 in recent memory... 162 00:09:57,063 --> 00:10:03,835 the 1991 eruption of Mount Pinatubo in the Philippines. 163 00:10:06,339 --> 00:10:09,040 Unlike volcanoes that erupt by pouring out rivers 164 00:10:09,075 --> 00:10:14,078 of molten lava over a long period of time, 165 00:10:14,114 --> 00:10:17,782 Pinatubo erupted suddenly and violently... 166 00:10:21,087 --> 00:10:23,054 ...when water and gases trapped inside the magma 167 00:10:23,089 --> 00:10:26,691 exploded with tremendous force, 168 00:10:26,726 --> 00:10:32,964 shattering the rock into millions of tiny particles 169 00:10:32,999 --> 00:10:36,401 and sending them high into the atmosphere. 170 00:10:36,436 --> 00:10:42,340 Explosive eruptions like this are the most dangerous of all. 171 00:10:44,477 --> 00:10:48,880 Pinatubo killed 847 people locally, 172 00:10:48,915 --> 00:10:53,017 and left over 200,000 homeless. 173 00:10:53,053 --> 00:10:57,055 But as with the other big Indonesian volcano, 174 00:10:57,090 --> 00:11:02,260 Mount Tambora, this eruption also had far-reaching effects. 175 00:11:02,295 --> 00:11:07,665 NASA's satellites were able to monitor the eruption. 176 00:11:07,701 --> 00:11:12,770 Pinatubo blasted out one cubic mile of superheated ash, 177 00:11:12,806 --> 00:11:16,274 but it also ejected hundreds of millions of tons 178 00:11:16,309 --> 00:11:19,043 of volcanic gases 179 00:11:19,079 --> 00:11:21,279 in a plume 22 miles high. 180 00:11:21,314 --> 00:11:24,515 KOMOROWSKI: The ash and the gases 181 00:11:24,551 --> 00:11:26,718 are dispersed through the atmosphere by the wind, 182 00:11:26,753 --> 00:11:28,653 and they can travel thousands of kilometers, 183 00:11:28,688 --> 00:11:29,787 tens of thousands of kilometers. 184 00:11:32,692 --> 00:11:34,926 NARRATOR: But unlike heavy ash 185 00:11:34,961 --> 00:11:37,061 that soon falls out of the atmosphere, 186 00:11:37,097 --> 00:11:41,866 the lightweight gases persist for much longer. 187 00:11:41,902 --> 00:11:45,803 The most impactful gases are the sulphur-rich gases. 188 00:11:45,839 --> 00:11:49,540 And those gases will form little droplets of sulphuric acid 189 00:11:49,576 --> 00:11:50,909 in a large cloud. 190 00:11:52,979 --> 00:11:56,481 NARRATOR: The tiny drops of sulphuric acid are called aerosols. 191 00:11:56,516 --> 00:11:59,884 And in a large cloud, high in the upper atmosphere, 192 00:11:59,920 --> 00:12:02,954 these aerosols caused enough sunlight to reflect 193 00:12:02,989 --> 00:12:06,291 out into space to cool the planet. 194 00:12:06,326 --> 00:12:10,261 The satellite data revealed that this sulphuric acid mist 195 00:12:10,297 --> 00:12:13,898 had a much more dramatic impact than the ash. 196 00:12:13,934 --> 00:12:17,902 It blocked enough sunlight to cool the entire planet 197 00:12:17,938 --> 00:12:22,807 by one degree Fahrenheit for two years. 198 00:12:22,842 --> 00:12:25,376 That doesn't sound very much, but it actually masks 199 00:12:25,412 --> 00:12:27,011 much stronger regional variations. 200 00:12:27,047 --> 00:12:30,181 And that translates into real impact on the ground 201 00:12:30,216 --> 00:12:31,149 in terms of crop yields. 202 00:12:32,786 --> 00:12:36,788 NARRATOR: In 1258, the temperature drop was much greater 203 00:12:36,823 --> 00:12:39,424 than caused by Pinatubo. 204 00:12:39,459 --> 00:12:43,094 This suggests that whatever triggered this medieval disaster 205 00:12:43,129 --> 00:12:45,430 could have been much bigger. 206 00:12:50,036 --> 00:12:53,171 That indicated that a big event occurred somewhere in the world. 207 00:12:53,206 --> 00:12:57,508 But there was no record of a massive volcanic eruption. 208 00:12:58,545 --> 00:13:00,478 OPPENHEIMER: For volcanologists, 209 00:13:00,513 --> 00:13:01,746 it was the biggest mystery for us. 210 00:13:04,651 --> 00:13:07,185 NARRATOR: So where could the culprit volcano have been? 211 00:13:07,220 --> 00:13:11,956 And after more than 750 years, could this killer volcano 212 00:13:11,992 --> 00:13:13,124 be found? 213 00:13:15,161 --> 00:13:18,963 It seemed the trail had gone cold, 214 00:13:18,999 --> 00:13:20,999 until a clue appeared, 215 00:13:21,034 --> 00:13:22,633 frozen in the polar ice. 216 00:13:27,841 --> 00:13:31,876 About 1,000 miles from the North Pole... 217 00:13:34,614 --> 00:13:37,749 ...researchers for the Greenland Ice Sheet Project 218 00:13:37,784 --> 00:13:42,153 are taking core samples from deep in the ice. 219 00:13:47,894 --> 00:13:51,162 This ice sheet was built layer by layer 220 00:13:51,197 --> 00:13:56,167 as snowfall accumulated over 130,000 years. 221 00:13:57,604 --> 00:14:01,639 The deeper into the ice the scientists drill, 222 00:14:01,674 --> 00:14:04,342 the farther back in time they can look. 223 00:14:07,414 --> 00:14:11,249 The samples arrive for analysis at the Desert Research Institute 224 00:14:11,284 --> 00:14:12,383 in Nevada. 225 00:14:16,056 --> 00:14:20,425 Geochemist Nelia Dunbar and glaciologist Joe McConnell 226 00:14:20,460 --> 00:14:23,928 are preparing to analyze an Arctic ice core sample 227 00:14:23,963 --> 00:14:27,331 that contains snowfall from the mid 13th century. 228 00:14:27,367 --> 00:14:30,668 The core comes from 1,000 feet below the surface 229 00:14:30,703 --> 00:14:32,470 of the ice sheet. 230 00:14:32,505 --> 00:14:35,773 They will be looking for sulphuric acid-- 231 00:14:35,809 --> 00:14:37,742 evidence of an intense eruption. 232 00:14:37,777 --> 00:14:40,578 NELIA DUNBAR: If there were a big volcanic eruption 233 00:14:40,613 --> 00:14:41,879 that produced a lot of sulphur, 234 00:14:41,915 --> 00:14:44,715 that sulphur should be preserved in this ice. 235 00:14:44,751 --> 00:14:46,584 And that's what we're interested in studying. 236 00:14:46,619 --> 00:14:49,120 Where is this from, and what's the age of it? 237 00:14:49,155 --> 00:14:52,657 McCONNELL: So this piece is from around 1250, 1255 AD. 238 00:14:52,692 --> 00:14:56,661 This represents about three years. 239 00:14:56,696 --> 00:14:58,262 So this is roughly one year, 240 00:14:58,298 --> 00:15:00,398 roughly one year, and roughly one year. 241 00:15:03,636 --> 00:15:05,436 These ice cores hold an incredible record 242 00:15:05,472 --> 00:15:07,138 of past climate. 243 00:15:07,173 --> 00:15:10,608 In between the snow crystals are little pockets of atmosphere 244 00:15:10,643 --> 00:15:13,311 that are little time capsules that represent 245 00:15:13,346 --> 00:15:14,979 the composition of the atmosphere 246 00:15:15,014 --> 00:15:18,015 at the time the snow fell. 247 00:15:18,051 --> 00:15:20,384 Over time, more snow will fall on the ice sheet, 248 00:15:20,420 --> 00:15:22,220 and that record is locked in. 249 00:15:24,157 --> 00:15:26,424 Up to the right and then up to the top. 250 00:15:26,459 --> 00:15:29,093 NARRATOR: But to unlock the record, 251 00:15:29,129 --> 00:15:33,531 scientists have to destroy it inch by inch. 252 00:15:33,566 --> 00:15:36,300 Okay, so now we're ready to start the analysis. 253 00:15:36,336 --> 00:15:38,202 Okay. 254 00:15:40,106 --> 00:15:43,107 NARRATOR: As each layer of ice melts down, 255 00:15:43,143 --> 00:15:46,544 the melt water passes through a mass spectrometer. 256 00:15:46,579 --> 00:15:49,747 It's like a time machine 257 00:15:49,782 --> 00:15:51,549 that reads out the chemicals 258 00:15:51,584 --> 00:15:54,552 that were in the atmosphere hundreds of years ago. 259 00:15:57,290 --> 00:15:59,423 The results start to come through. 260 00:16:02,562 --> 00:16:05,730 And the team immediately sees a telltale spike. 261 00:16:05,765 --> 00:16:07,899 McCONNELL: So we're seeing the responses 262 00:16:07,934 --> 00:16:09,767 come up on all the various instruments right now. 263 00:16:09,802 --> 00:16:14,338 So this would be 1258, and you can see the acid now 264 00:16:14,374 --> 00:16:15,606 has just skyrocketed, 265 00:16:15,642 --> 00:16:18,676 a huge increase in sulphur. 266 00:16:18,711 --> 00:16:20,077 So it's certainly pointing to volcanism. 267 00:16:20,113 --> 00:16:22,380 Okay, so that must have been a really big volcanic event. 268 00:16:22,415 --> 00:16:24,015 McCONNELL: Yeah, absolutely huge. 269 00:16:24,050 --> 00:16:26,517 NARRATOR: The sulphur locked inside 270 00:16:26,553 --> 00:16:29,053 the 1258 ice layer tells the story 271 00:16:29,088 --> 00:16:31,322 of a powerful volcanic eruption. 272 00:16:33,726 --> 00:16:37,328 And though the sulphur was washed out of the atmosphere 273 00:16:37,363 --> 00:16:41,265 in rain and snow in 1258, 274 00:16:41,301 --> 00:16:45,903 the eruption itself likely occurred the year before. 275 00:16:47,607 --> 00:16:49,006 Now, keep in mind 276 00:16:49,042 --> 00:16:50,942 that it takes a while for the sulphur to make it 277 00:16:50,977 --> 00:16:52,343 from the volcano through the atmosphere 278 00:16:52,378 --> 00:16:53,744 and be deposited on the ice sheet. 279 00:16:53,780 --> 00:16:55,146 DUNBAR: Mm-hmm. 280 00:16:55,181 --> 00:16:56,914 And so this event, it probably occurred in maybe 281 00:16:56,950 --> 00:16:57,882 mid to late 1257. 282 00:16:59,619 --> 00:17:02,453 NARRATOR: And the amount of sulphur ejected by this eruption 283 00:17:02,488 --> 00:17:06,891 was vast by comparison with that produced 284 00:17:06,926 --> 00:17:09,293 by the other known eruptions captured in the ice cores. 285 00:17:09,329 --> 00:17:12,496 Here's the 1257 of that that we just measured again 286 00:17:12,532 --> 00:17:14,799 in this new ice core. 287 00:17:14,834 --> 00:17:16,434 We can see that it's huge. 288 00:17:16,469 --> 00:17:19,537 When you compare it to Tambora, here in 1815, it's, you know, 289 00:17:19,572 --> 00:17:22,039 something like more than twice as big. 290 00:17:22,075 --> 00:17:24,108 So this is a really, really big event. 291 00:17:24,143 --> 00:17:25,610 And at least in this composite it's the biggest event 292 00:17:25,645 --> 00:17:28,879 of the last 2,000 years, very clearly. 293 00:17:30,316 --> 00:17:33,718 NARRATOR: So this eruption seems to have been large enough 294 00:17:33,753 --> 00:17:35,353 to account for the freak climate disaster 295 00:17:35,388 --> 00:17:38,623 across the Northern Hemisphere in 1258, 296 00:17:38,658 --> 00:17:41,259 including London's deadly famine. 297 00:17:41,294 --> 00:17:44,762 OPPENHEIMER: It was hard to really pin down one event and say, 298 00:17:44,797 --> 00:17:47,331 "This was the result of a volcanic eruption." 299 00:17:47,367 --> 00:17:50,368 But I think in this case the evidence is quite strong. 300 00:17:52,205 --> 00:17:54,338 You can imagine living in medieval London. 301 00:17:54,374 --> 00:17:56,374 You know that you haven't got enough food to live, 302 00:17:56,409 --> 00:18:00,177 your crops are failing, the weather's very bad, 303 00:18:00,213 --> 00:18:05,049 but you'd have no idea the true cause of what was going on. 304 00:18:09,689 --> 00:18:10,755 NARRATOR: The true cause 305 00:18:10,790 --> 00:18:14,025 was that somewhere on the planet, in 1257, 306 00:18:14,060 --> 00:18:17,728 a volcano exploded and blasted its contents, 307 00:18:17,764 --> 00:18:21,299 including poisonous gas and ash, high into the atmosphere, 308 00:18:21,334 --> 00:18:24,869 where it dimmed the sun for months, if not years. 309 00:18:29,275 --> 00:18:32,009 But where was this killer? 310 00:18:32,045 --> 00:18:35,012 The mystery that remains is what was the volcano 311 00:18:35,048 --> 00:18:38,149 that was responsible for this big volcanic eruption? 312 00:18:40,019 --> 00:18:42,420 NARRATOR: More than 1,500 volcanoes 313 00:18:42,455 --> 00:18:45,089 have been active in the last 10,000 years, 314 00:18:45,124 --> 00:18:48,426 so pinpointing which of these caused 315 00:18:48,461 --> 00:18:54,665 such a massive disruption in 1258 is a huge challenge. 316 00:18:54,701 --> 00:18:59,270 The first place to look is a string of volcanoes 317 00:18:59,305 --> 00:19:01,439 known as the Pacific Ring of Fire. 318 00:19:03,242 --> 00:19:05,409 The continents we live on 319 00:19:05,445 --> 00:19:10,181 ride atop giant tectonic plates made of rock. 320 00:19:10,216 --> 00:19:13,417 Where plates collide or slide under each other 321 00:19:13,453 --> 00:19:16,253 gives rise to volcanoes, 322 00:19:16,289 --> 00:19:20,191 making this one of the most geologically active regions 323 00:19:20,226 --> 00:19:22,526 of the world. 324 00:19:22,562 --> 00:19:27,465 But the Ring of Fire extends for thousands of miles. 325 00:19:27,500 --> 00:19:31,902 How can scientists work out which volcano is the culprit? 326 00:19:36,442 --> 00:19:40,177 In her lab at the New Mexico Bureau of Geology, 327 00:19:40,213 --> 00:19:43,347 Nelia Dunbar examines some distinctively shaped 328 00:19:43,383 --> 00:19:46,283 mineral particles lodged in a section of ice 329 00:19:46,319 --> 00:19:48,285 from a different Greenland ice core. 330 00:19:48,321 --> 00:19:52,390 The particles also date to 1258, 331 00:19:52,425 --> 00:19:56,127 when the sulphur concentrations are highest. 332 00:19:58,131 --> 00:20:00,464 Could these particles be possible clues 333 00:20:00,500 --> 00:20:03,601 to the volcano's identity? 334 00:20:05,171 --> 00:20:08,139 At 50,000 times magnification, 335 00:20:08,174 --> 00:20:10,241 it's clear that the mineral particles 336 00:20:10,276 --> 00:20:13,411 are actually microscopic pieces of volcanic ash. 337 00:20:13,446 --> 00:20:17,715 DUNBAR: These particles are smaller than a human hair. 338 00:20:20,052 --> 00:20:21,419 NARRATOR: The ash particles 339 00:20:21,454 --> 00:20:23,921 are fragments of shattered pumice, 340 00:20:23,956 --> 00:20:28,359 produced when magma cools rapidly during an eruption. 341 00:20:28,394 --> 00:20:30,194 And their chemical composition 342 00:20:30,229 --> 00:20:35,766 is unique to each volcanic eruption. 343 00:20:35,802 --> 00:20:37,902 Just like a human fingerprint allows a suspect 344 00:20:37,937 --> 00:20:41,505 to be identified, the chemical composition of an ash layer 345 00:20:41,541 --> 00:20:44,341 allows the source volcano to be identified. 346 00:20:44,377 --> 00:20:50,881 NARRATOR: This unique signature didn't match any known volcano. 347 00:20:54,654 --> 00:20:59,223 But it did show up in one other surprising place... 348 00:21:01,761 --> 00:21:05,429 ...at the exact opposite end of the world, 349 00:21:05,465 --> 00:21:08,933 in ice cores taken from the South Pole. 350 00:21:10,837 --> 00:21:14,405 These cores also contained a significant spike 351 00:21:14,440 --> 00:21:17,107 in sulphuric acid, 352 00:21:17,143 --> 00:21:19,610 corresponding to the eruption in 1257. 353 00:21:19,645 --> 00:21:23,614 This means that the monster darkened not only 354 00:21:23,649 --> 00:21:28,652 the Northern Hemisphere, but the Southern Hemisphere as well, 355 00:21:28,688 --> 00:21:33,791 smothering the entire world in a blanket of sulphuric acid. 356 00:21:37,530 --> 00:21:39,897 Climatologist Michael Mills 357 00:21:39,932 --> 00:21:42,967 believes the size of this global cloud 358 00:21:43,002 --> 00:21:46,237 can help pinpoint the place where the volcano erupted. 359 00:21:48,441 --> 00:21:50,074 He uses satellite data 360 00:21:50,109 --> 00:21:53,344 to map how clouds of sulphuric acid aerosols 361 00:21:53,379 --> 00:21:55,179 disperse around the world. 362 00:21:57,517 --> 00:21:58,983 Let's look at what happens when you have an eruption 363 00:21:59,018 --> 00:22:01,151 in the Northern Hemisphere. 364 00:22:01,187 --> 00:22:04,622 In 2008, we had several eruptions, 365 00:22:04,657 --> 00:22:08,459 and the aerosol stays in the Northern Hemisphere. 366 00:22:08,494 --> 00:22:10,895 Now look at what happens 367 00:22:10,930 --> 00:22:13,497 when you have an eruption in the Southern Hemisphere. 368 00:22:13,533 --> 00:22:16,667 The aerosol spreads, and will remain 369 00:22:16,702 --> 00:22:19,436 in the Southern Hemisphere. 370 00:22:19,472 --> 00:22:23,140 NARRATOR: But how could an aerosol cloud reach both hemispheres? 371 00:22:23,175 --> 00:22:28,612 For that, an eruption has to occur within a narrow band 372 00:22:28,648 --> 00:22:30,881 around the middle of the globe. 373 00:22:32,818 --> 00:22:35,819 This is Pinatubo in June of 1991, 374 00:22:35,855 --> 00:22:37,521 in the Philippines. 375 00:22:37,557 --> 00:22:40,624 It starts spreading throughout the tropics, 376 00:22:40,660 --> 00:22:43,561 and from there, it spreads 377 00:22:43,596 --> 00:22:47,898 into the Northern Hemisphere and to the Southern Hemisphere. 378 00:22:47,934 --> 00:22:50,167 Within a year after the eruption, 379 00:22:50,202 --> 00:22:53,837 the aerosol has covered the globe from pole to pole, 380 00:22:53,873 --> 00:22:55,806 affecting temperatures globally. 381 00:22:57,176 --> 00:23:00,844 NARRATOR: The mystery eruption of 1257 382 00:23:00,880 --> 00:23:05,416 also spread a cloud of sulphuric acid over both poles. 383 00:23:05,451 --> 00:23:11,956 So it too must have erupted near the equator. 384 00:23:11,991 --> 00:23:16,460 But that still leaves over 700 possible volcanoes as suspects, 385 00:23:16,495 --> 00:23:20,698 like Mount Tambora, that led to the year without a summer, 386 00:23:20,733 --> 00:23:26,303 Krakatoa, that also erupted in Indonesia in 1883, 387 00:23:26,339 --> 00:23:31,008 and El Chichon in Mexico, that erupted in 1982. 388 00:23:31,043 --> 00:23:34,111 Any one of hundreds of tropical volcanoes 389 00:23:34,146 --> 00:23:36,080 could have caused thousands of deaths 390 00:23:36,115 --> 00:23:38,949 on the other side of the planet, but which one, 391 00:23:38,985 --> 00:23:40,784 and could it strike again? 392 00:23:40,820 --> 00:23:42,987 OPPENHEIMER: It's still a needle in a haystack 393 00:23:43,022 --> 00:23:46,256 to find the one volcano, the one eruption 394 00:23:46,292 --> 00:23:48,492 that triggered all of this, because there are 395 00:23:48,527 --> 00:23:51,729 so many volcanoes, even if you narrow it down to the tropics, 396 00:23:51,764 --> 00:23:53,263 where do you start? 397 00:23:55,401 --> 00:23:58,402 NARRATOR: It seemed an impossible mystery to solve. 398 00:24:02,108 --> 00:24:03,540 But then a French geographer 399 00:24:03,576 --> 00:24:06,510 named Franck Lavigne decided to take it on. 400 00:24:08,814 --> 00:24:10,447 LAVIGNE: For me it looks 401 00:24:10,483 --> 00:24:14,184 a bit strange that nobody found this eruption. 402 00:24:14,220 --> 00:24:16,987 So I decided to take up the challenge. 403 00:24:17,023 --> 00:24:21,325 NARRATOR: He approaches it as a detective. 404 00:24:21,360 --> 00:24:25,062 LAVIGNE: Trying to find the identity of this mystery volcano 405 00:24:25,097 --> 00:24:27,398 was like a crime scene. 406 00:24:27,433 --> 00:24:28,899 So we needed to investigate, 407 00:24:28,934 --> 00:24:31,902 to look for culprits, to look for clues. 408 00:24:31,937 --> 00:24:35,439 NARRATOR: Volcanologist Jean-Christophe Komorowski 409 00:24:35,474 --> 00:24:38,809 joins the investigation. 410 00:24:38,844 --> 00:24:40,544 KOMOROWSKI: It's a very large eruption. 411 00:24:40,579 --> 00:24:43,447 It's an unknown eruption, so it has to be in a country 412 00:24:43,482 --> 00:24:46,750 where there are many, many volcanoes, 413 00:24:46,786 --> 00:24:49,286 most of them perhaps have not been studied. 414 00:24:49,321 --> 00:24:52,990 NARRATOR: The team focuses on one particularly active region 415 00:24:53,025 --> 00:24:55,526 of the Pacific Ring of Fire-- 416 00:24:55,561 --> 00:25:00,698 Indonesia, home of the once deadly Mount Tambora, 417 00:25:00,733 --> 00:25:04,268 that last erupted in 1815. 418 00:25:04,303 --> 00:25:08,439 With 129 active volcanoes spread over 3,000 miles, 419 00:25:08,474 --> 00:25:14,211 Indonesia is the most volcanic country in the tropics. 420 00:25:14,246 --> 00:25:19,550 It is also one of the most unstudied and mysterious. 421 00:25:19,585 --> 00:25:21,218 KOMOROWSKI: Indonesia has 422 00:25:21,253 --> 00:25:23,487 the second largest number of active volcanoes in the world. 423 00:25:23,522 --> 00:25:27,758 NARRATOR: Indonesia marks the place 424 00:25:27,793 --> 00:25:31,495 where two giant tectonic plates collide. 425 00:25:31,530 --> 00:25:34,798 Here, one plate dives under the other 426 00:25:34,834 --> 00:25:37,534 in a process called subduction. 427 00:25:37,570 --> 00:25:40,971 At depth, the diving plate releases water, 428 00:25:41,006 --> 00:25:44,808 which lowers the melting point of the hot rock above. 429 00:25:44,844 --> 00:25:49,646 The rock melts, forming giant bubbles of magma that rise up, 430 00:25:49,682 --> 00:25:52,282 forcing their way through the Earth's crust, 431 00:25:52,318 --> 00:25:54,284 until the magma erupts 432 00:25:54,320 --> 00:25:55,853 at the surface. 433 00:26:00,426 --> 00:26:03,560 Today, the most dangerous Indonesian volcano 434 00:26:03,596 --> 00:26:06,530 is Mount Merapi on the island of Java. 435 00:26:06,565 --> 00:26:12,102 This volcano erupts explosively every few years... 436 00:26:16,208 --> 00:26:18,208 ...threatening hundreds of thousands of people 437 00:26:18,244 --> 00:26:19,510 who live in its shadow. 438 00:26:24,416 --> 00:26:27,384 AGUS BUDI SANTOSO: Merapi volcano is considered 439 00:26:27,419 --> 00:26:29,953 to be one of the most active volcanoes in the world. 440 00:26:33,192 --> 00:26:35,259 NARRATOR: The last major eruption 441 00:26:35,294 --> 00:26:38,362 was in 2010. 442 00:26:38,397 --> 00:26:41,598 400,000 people evacuated. 443 00:26:41,634 --> 00:26:45,936 Even so, more than 200 died in the avalanches 444 00:26:45,971 --> 00:26:47,738 of superheated ash and rock, 445 00:26:47,773 --> 00:26:52,342 called pyroclastic flows. 446 00:26:52,378 --> 00:26:56,947 20,000 were left without homes. 447 00:27:01,587 --> 00:27:03,987 The ash produced by Merapi 448 00:27:04,023 --> 00:27:05,689 does not match the chemical fingerprint 449 00:27:05,724 --> 00:27:08,392 of the ash in the ice cores. 450 00:27:08,427 --> 00:27:11,929 But understanding the forces that make this volcano 451 00:27:11,964 --> 00:27:17,501 so dangerous sheds light on all of Indonesia's active volcanoes. 452 00:27:17,536 --> 00:27:23,841 So which one exploded so catastrophically in 1257? 453 00:27:23,876 --> 00:27:26,743 Geographer Lavigne 454 00:27:26,779 --> 00:27:30,514 hunts through satellite images for large volcanic craters 455 00:27:30,549 --> 00:27:34,818 and other telltale signs. 456 00:27:34,854 --> 00:27:36,486 And one of these clues is a large volume of pumice 457 00:27:36,522 --> 00:27:38,822 all around the volcano. 458 00:27:38,858 --> 00:27:43,827 NARRATOR: Pumice, a rough textured rock, is solidified magma, 459 00:27:43,863 --> 00:27:48,232 blasted out during explosive eruptions. 460 00:27:51,136 --> 00:27:53,737 When you suddenly depressurize 461 00:27:53,772 --> 00:27:56,974 and cool magma that was very rich in gas, 462 00:27:57,009 --> 00:27:58,609 it forms this very lightweight, 463 00:27:58,644 --> 00:28:01,578 foamy rock, which is pumice. 464 00:28:01,614 --> 00:28:07,084 NARRATOR: It can be a deadly material. 465 00:28:07,119 --> 00:28:12,022 When Mount Vesuvius erupted in Italy in 79 the Common Era, 466 00:28:12,057 --> 00:28:15,893 it entombed the town and the people of Pompeii 467 00:28:15,928 --> 00:28:19,763 in layers of pumice 16 feet deep. 468 00:28:19,798 --> 00:28:25,535 Throughout Indonesia today, pumice mines dig out 469 00:28:25,571 --> 00:28:27,704 this volcanic material, primarily for use 470 00:28:27,740 --> 00:28:29,539 in the construction industry. 471 00:28:29,575 --> 00:28:34,578 And the scars left by the quarrying work are so extensive 472 00:28:34,613 --> 00:28:38,515 that they're visible from space, making it easy for scientists 473 00:28:38,550 --> 00:28:42,185 to pinpoint locations for further investigation. 474 00:28:42,221 --> 00:28:45,255 Journeying to Indonesia, 475 00:28:45,291 --> 00:28:47,858 Lavigne works with partners from the government's 476 00:28:47,893 --> 00:28:51,361 geological agency and Indonesian universities. 477 00:28:51,397 --> 00:28:57,067 They visit several volcanoes, with no success. 478 00:28:57,102 --> 00:29:00,804 At each site, the pumice is compacted and hard, 479 00:29:00,839 --> 00:29:03,206 likely too ancient to have been created 480 00:29:03,242 --> 00:29:06,777 during the 1257 eruption. 481 00:29:06,812 --> 00:29:08,478 (translated): It seemed older 482 00:29:08,514 --> 00:29:13,150 than we had predicted, so older than the 13th century. 483 00:29:15,254 --> 00:29:18,488 NARRATOR: Then the team sees something intriguing 484 00:29:18,524 --> 00:29:21,558 in the satellite images, and decides to narrow its search 485 00:29:21,593 --> 00:29:24,628 to the island of Lombok, just east of Bali. 486 00:29:26,732 --> 00:29:29,132 This island is quite a big island, 487 00:29:29,168 --> 00:29:31,969 with a very big crater. 488 00:29:37,309 --> 00:29:40,110 NARRATOR: Stretching four miles across 489 00:29:40,145 --> 00:29:42,946 and over two and a half thousand feet deep, 490 00:29:42,982 --> 00:29:46,049 this giant crater is called a caldera. 491 00:29:46,085 --> 00:29:51,288 It's what remains of a volcanic system known as Mount Rinjani. 492 00:29:51,323 --> 00:29:54,925 When you have a very large explosive eruption, 493 00:29:54,960 --> 00:29:58,595 you're left at the end of the eruption with a huge hole. 494 00:29:58,630 --> 00:30:02,432 NARRATOR: To the team's expert eyes, it looks like there were 495 00:30:02,468 --> 00:30:08,205 not one, but two giant volcanic peaks here in the past-- 496 00:30:08,240 --> 00:30:13,410 Mount Rinjani itself, and a second peak that once rose 497 00:30:13,445 --> 00:30:15,979 above the main part of the caldera. 498 00:30:16,015 --> 00:30:21,118 Today, inside this caldera is now a small volcanic cone-- 499 00:30:21,153 --> 00:30:22,819 Mount Barujari. 500 00:30:24,289 --> 00:30:27,591 Surrounded by a rainwater lake, 501 00:30:27,626 --> 00:30:30,193 Mount Barujari is the part of the volcanic system 502 00:30:30,229 --> 00:30:31,828 that is still active. 503 00:30:39,872 --> 00:30:42,706 In 2015 and 2016, 504 00:30:42,741 --> 00:30:45,776 this small cone erupted with enough force 505 00:30:45,811 --> 00:30:50,013 to send plumes of ash thousands of feet into the atmosphere, 506 00:30:50,049 --> 00:30:52,983 disrupting international flights in the area. 507 00:30:55,220 --> 00:31:02,859 It's far too small to be the source of the mystery eruption, 508 00:31:02,895 --> 00:31:06,430 but the caldera it sits in is large enough 509 00:31:06,465 --> 00:31:09,699 to have been created during a much more powerful eruption. 510 00:31:14,406 --> 00:31:17,641 And all around the Mount Rinjani volcanic system 511 00:31:17,676 --> 00:31:20,510 are pumice quarries. 512 00:31:20,546 --> 00:31:22,546 Everywhere in the island 513 00:31:22,581 --> 00:31:26,316 you can find a pumice quarry. 514 00:31:26,351 --> 00:31:28,785 NARRATOR: Could the pumice in these quarries be dated 515 00:31:28,821 --> 00:31:30,887 to help in their investigation? 516 00:31:35,461 --> 00:31:39,830 The team travels to Lombok. 517 00:31:42,801 --> 00:31:46,503 And the hunt starts in the shadow of Mount Rinjani... 518 00:31:50,409 --> 00:31:55,479 ...a peak that soars 12,000 feet high. 519 00:32:01,286 --> 00:32:04,187 On the island, they join forces with more Indonesian experts. 520 00:32:09,361 --> 00:32:11,128 They head for the quarries 521 00:32:11,163 --> 00:32:15,765 identified in the satellite images. 522 00:32:19,204 --> 00:32:23,840 And as soon as they arrive, they discover something remarkable. 523 00:32:23,876 --> 00:32:30,714 The volcanic pumice deposits are at least 120 feet deep. 524 00:32:37,356 --> 00:32:39,322 LAVIGNE: Here we are, 525 00:32:39,358 --> 00:32:41,458 looking at the huge volcanic deposit. 526 00:32:41,493 --> 00:32:45,228 And that's very rare, 527 00:32:45,264 --> 00:32:46,863 to find so thick deposit 528 00:32:46,899 --> 00:32:51,468 very far away from the summit of the volcano. 529 00:32:51,503 --> 00:32:55,539 NARRATOR: Pompeii, just over five miles 530 00:32:55,574 --> 00:32:57,774 from the erupting Mount Vesuvius, was buried 531 00:32:57,809 --> 00:33:00,110 under 16 feet of pumice. 532 00:33:00,145 --> 00:33:05,549 Here, the deposits of pumice and ash are at least 533 00:33:05,584 --> 00:33:08,919 six times thicker, and they are much farther away 534 00:33:08,954 --> 00:33:13,857 from Mount Rinjani than Pompeii was from Mount Vesuvius. 535 00:33:13,892 --> 00:33:18,161 It's a sign of a giant eruption. 536 00:33:18,197 --> 00:33:21,064 KOMOROWSKI: You're dealing with a very massive eruption. 537 00:33:21,099 --> 00:33:22,832 Much larger than the Pompeii eruption, 538 00:33:22,868 --> 00:33:26,069 and probably also much larger than the Pinatubo eruption 539 00:33:26,104 --> 00:33:27,237 in 1991. 540 00:33:31,910 --> 00:33:35,045 NARRATOR: And it looks to them as though the ash and pumice 541 00:33:35,080 --> 00:33:39,816 flowed down from the volcano in vast avalanches. 542 00:33:43,255 --> 00:33:45,655 KOMOROWSKI: You can see it's very rich in finer material. 543 00:33:45,691 --> 00:33:48,959 It's not pumice falling from a column, raining down. 544 00:33:48,994 --> 00:33:51,595 It's an avalanche of incandescent, 545 00:33:51,630 --> 00:33:53,430 hot volcanic rocks mixed with gases. 546 00:33:56,602 --> 00:33:57,667 My first impression, 547 00:33:57,703 --> 00:33:59,936 when I saw such a huge deposit, 548 00:33:59,972 --> 00:34:02,739 was that we have here a very serious candidate 549 00:34:02,774 --> 00:34:03,840 for the mystery eruption. 550 00:34:09,081 --> 00:34:10,413 NARRATOR: But is all this pumice 551 00:34:10,449 --> 00:34:16,086 from the mystery eruption of 1257? 552 00:34:16,121 --> 00:34:19,656 KOMOROWSKI: To confirm that this eruption is the 1257 eruption, 553 00:34:19,691 --> 00:34:24,194 we need to try to find charcoal, wood logs that were burned 554 00:34:24,229 --> 00:34:27,697 by this eruption, carried by the pyroclastic flow, 555 00:34:27,733 --> 00:34:30,267 and settling here, and we need to date those. 556 00:34:32,537 --> 00:34:36,439 NARRATOR: If they can find burned wood, they can radiocarbon-date it, 557 00:34:36,475 --> 00:34:39,976 since, unlike pumice, wood contains carbon 558 00:34:40,012 --> 00:34:42,012 absorbed from the atmosphere. 559 00:34:42,047 --> 00:34:44,614 And by taking samples of the pumice itself, 560 00:34:44,650 --> 00:34:48,385 the team hopes to compare its chemistry 561 00:34:48,420 --> 00:34:53,156 with the fragments of volcanic ash from the polar ice cores. 562 00:34:55,727 --> 00:34:59,296 But Lavigne still needs more evidence, so he decides 563 00:34:59,331 --> 00:35:01,164 to investigate Lombok's past 564 00:35:01,199 --> 00:35:06,069 to see if he can find records of historic eruptions. 565 00:35:11,043 --> 00:35:12,575 Under lock and key in the museum 566 00:35:12,611 --> 00:35:15,011 of Lombok's capital city, Mataram, 567 00:35:15,047 --> 00:35:17,847 is an original text, 568 00:35:17,883 --> 00:35:20,650 written on dried palm leaves, 569 00:35:20,686 --> 00:35:23,320 in an old Javanese script. 570 00:35:27,326 --> 00:35:30,760 Called the Babad Lombok, 571 00:35:30,796 --> 00:35:35,732 this text is a rare account of Lombok's history. 572 00:35:35,767 --> 00:35:37,734 (translated): It chronicles the story 573 00:35:37,769 --> 00:35:41,438 of Lombok, from prehistoric times to historic times. 574 00:35:41,473 --> 00:35:45,241 NARRATOR: And hidden in this document 575 00:35:45,277 --> 00:35:48,044 is a remarkable account that historians have dated 576 00:35:48,080 --> 00:35:50,180 to the 13th century. 577 00:35:51,383 --> 00:35:54,184 (translated): Mount Rinjani avalanched, 578 00:35:54,219 --> 00:35:57,053 and Mount Samalas collapsed. 579 00:35:57,089 --> 00:35:59,589 Rocks flooded down in rows. 580 00:36:03,428 --> 00:36:06,129 LAVIGNE: It describes a huge volcanic eruption 581 00:36:06,164 --> 00:36:07,797 that occurred in Lombok. 582 00:36:09,534 --> 00:36:11,868 NARRATOR: Lavigne is familiar with Mount Rinjani, 583 00:36:11,903 --> 00:36:17,741 mentioned in the text, but not the name of the volcano 584 00:36:17,776 --> 00:36:22,178 that's described as collapsing-- Mount Samalas. 585 00:36:22,214 --> 00:36:24,581 This description is absolutely fantastic, 586 00:36:24,616 --> 00:36:29,853 because it mentions the name of a new volcano, Mount Samalas. 587 00:36:29,888 --> 00:36:32,088 I never heard about this before. 588 00:36:33,558 --> 00:36:37,260 NARRATOR: This remarkable discovery raises a new question-- 589 00:36:37,295 --> 00:36:42,665 could the giant caldera the team saw on satellite images 590 00:36:42,701 --> 00:36:46,302 belong to the unknown Mount Samalas? 591 00:36:46,338 --> 00:36:52,809 The text also reveals the scale of the human catastrophe. 592 00:36:52,844 --> 00:36:54,577 LAVIGNE: The text in the Babad 593 00:36:54,613 --> 00:36:59,048 says these flows destroyed the seat of the kingdom, Pamatan. 594 00:36:59,084 --> 00:37:02,685 All houses were destroyed and swept away, 595 00:37:02,721 --> 00:37:05,588 floating on the sea, and many people die. 596 00:37:05,624 --> 00:37:08,691 There is a strong possibility of the remains of this capital 597 00:37:08,727 --> 00:37:13,763 still lie preserved beneath the pumice, just like Pompeii. 598 00:37:13,799 --> 00:37:16,499 NARRATOR: The text is a tantalizing clue, 599 00:37:16,535 --> 00:37:20,970 but could it just be a myth? 600 00:37:21,006 --> 00:37:25,341 LAVIGNE: It made this volcano our chief suspect in our investigations, 601 00:37:25,377 --> 00:37:29,946 but to confirm it was the one, we needed scientific proof. 602 00:37:34,052 --> 00:37:36,753 NARRATOR: So the team decides to mount an expedition. 603 00:37:41,760 --> 00:37:45,762 To trek into the mountains and hunt for hard evidence 604 00:37:45,797 --> 00:37:50,633 at an altitude of 9,000 feet. 605 00:37:59,878 --> 00:38:03,480 NARRATOR: From up here, the team can assess the landscape and geology 606 00:38:03,515 --> 00:38:06,249 in a way that's impossible from satellite images alone. 607 00:38:14,893 --> 00:38:18,027 Exposed in the cliffs are geological layers 608 00:38:18,063 --> 00:38:19,963 that allow Jean-Christophe Komorowski 609 00:38:19,998 --> 00:38:23,566 to work out the sequence of events that led 610 00:38:23,602 --> 00:38:25,001 to what we see today... 611 00:38:27,606 --> 00:38:29,305 ...the giant caldera. 612 00:38:31,776 --> 00:38:34,944 These cliffs are the remains of a very massive volcano. 613 00:38:37,582 --> 00:38:40,216 NARRATOR: And towering over the east side, 614 00:38:40,252 --> 00:38:46,389 the remains of Mount Rinjani. 615 00:38:46,424 --> 00:38:47,490 You can see the slopes 616 00:38:47,526 --> 00:38:51,861 of Mount Rinjani volcano rising to 3,700 meters. 617 00:38:51,897 --> 00:38:54,330 And it was much higher before. 618 00:38:54,366 --> 00:38:56,432 NARRATOR: The scars in the cliffs 619 00:38:56,468 --> 00:38:59,602 suggest to Komorowski that half of Mount Rinjani 620 00:38:59,638 --> 00:39:03,406 avalanched into the caldera after it formed. 621 00:39:03,441 --> 00:39:06,543 KOMOROWSKI: The formation of the Samalas caldera 622 00:39:06,578 --> 00:39:08,144 destabilized Mount Rinjani, 623 00:39:08,179 --> 00:39:11,014 which collapsed into the caldera, 624 00:39:11,049 --> 00:39:13,816 and this formed this massive sheer cliff here. 625 00:39:16,721 --> 00:39:20,723 NARRATOR: To the experts, it looks like Mount Samalas once stood 626 00:39:20,759 --> 00:39:22,258 next to Mount Rinjani, 627 00:39:22,294 --> 00:39:30,066 just as the ancient text describes. 628 00:39:30,101 --> 00:39:32,802 (translated): In fact, the latest research found that there was 629 00:39:32,837 --> 00:39:34,737 a volcanic mountain called Mount Samalas, 630 00:39:34,773 --> 00:39:38,775 which in the end is different than Mount Rinjani. 631 00:39:43,315 --> 00:39:46,482 NARRATOR: By extending the existing slopes of the volcano, 632 00:39:46,518 --> 00:39:50,720 experts have reconstructed what Mount Samalas looked like. 633 00:39:54,893 --> 00:39:56,826 KOMOROWSKI: Imagine that, before the eruption 634 00:39:56,861 --> 00:39:58,728 you had a huge conical volcano 635 00:39:58,763 --> 00:40:03,066 rising 1.6 kilometer above the rim of this giant hole. 636 00:40:03,101 --> 00:40:08,237 NARRATOR: That's an extra mile in height of volcanic mountain. 637 00:40:08,273 --> 00:40:11,474 So how did several cubic miles of rock disappear 638 00:40:11,509 --> 00:40:14,677 and leave an enormous caldera in its place? 639 00:40:14,713 --> 00:40:19,115 It all begins with a giant eruption. 640 00:40:19,150 --> 00:40:20,550 KOMOROWSKI: And in order to form a caldera, 641 00:40:20,585 --> 00:40:23,786 you have to have first a very massive explosive eruption. 642 00:40:26,091 --> 00:40:27,657 NARRATOR: In a magma chamber 643 00:40:27,692 --> 00:40:30,660 far beneath the volcano, the pressure rises, 644 00:40:30,695 --> 00:40:33,763 and finally cracks open the rock above. 645 00:40:33,798 --> 00:40:36,799 Magma blasts upwards. 646 00:40:36,835 --> 00:40:41,904 As this chamber empties, it becomes unstable. 647 00:40:41,940 --> 00:40:44,741 This destabilizes the whole volcano on top. 648 00:40:46,344 --> 00:40:48,978 NARRATOR: The roof of this partially empty chamber 649 00:40:49,014 --> 00:40:52,548 now cracks under the weight. 650 00:40:52,584 --> 00:40:53,983 And it collapses. 651 00:40:54,019 --> 00:40:58,354 NARRATOR: The entire top of the volcano caves in. 652 00:41:01,860 --> 00:41:05,328 Billions of tons of rock disappear as it falls 653 00:41:05,363 --> 00:41:09,465 thousands of feet down into the magma chamber below, 654 00:41:09,501 --> 00:41:11,501 forming a giant crater above... 655 00:41:14,172 --> 00:41:17,106 ...the enormous caldera. 656 00:41:18,410 --> 00:41:22,078 But that's not the end. 657 00:41:22,113 --> 00:41:24,047 KOMOROWSKI: As the volcano collapses on itself, 658 00:41:24,082 --> 00:41:26,416 it forms a massive explosive eruption, 659 00:41:26,451 --> 00:41:28,484 producing giant pyroclastic flows 660 00:41:28,520 --> 00:41:30,653 that sweep down the flanks of the volcano. 661 00:41:36,361 --> 00:41:38,494 NARRATOR: This catastrophic event 662 00:41:38,530 --> 00:41:40,663 explains the depth of the pumice deposits 663 00:41:40,699 --> 00:41:42,098 in the quarries, 664 00:41:42,133 --> 00:41:44,467 and closely aligns with the ancient story 665 00:41:44,502 --> 00:41:46,502 in the Babad Lombok. 666 00:41:48,273 --> 00:41:51,741 KOMOROWSKI: It gives a name to the volcano that existed 667 00:41:51,776 --> 00:41:53,976 at the beginning of the eruption, Mount Samalas, 668 00:41:54,012 --> 00:41:59,382 and it describes how Mount Samalas collapsed in on itself. 669 00:41:59,417 --> 00:42:02,518 Altogether, the description in the Babad matches remarkably 670 00:42:02,554 --> 00:42:04,721 what we have found in our field investigations. 671 00:42:06,825 --> 00:42:10,860 We now know that Babad was not a legend, 672 00:42:10,895 --> 00:42:12,328 but eyewitness accounts. 673 00:42:16,334 --> 00:42:18,701 NARRATOR: If the long-forgotten Mount Samalas 674 00:42:18,737 --> 00:42:20,703 was the source of the giant eruption on Lombok, 675 00:42:20,739 --> 00:42:24,540 as the evidence suggests, could it also be 676 00:42:24,576 --> 00:42:28,177 the mystery eruption of 1257? 677 00:42:30,515 --> 00:42:32,448 To answer that definitively, 678 00:42:32,484 --> 00:42:37,820 the team still needs more forensic evidence. 679 00:42:37,856 --> 00:42:40,389 OPPENHEIMER: It's really critical to get on the ground 680 00:42:40,425 --> 00:42:41,791 to look at the actual rocks themselves. 681 00:42:46,698 --> 00:42:48,131 NARRATOR: They take samples 682 00:42:48,166 --> 00:42:52,201 of pumice and ash from over 100 different sites 683 00:42:52,237 --> 00:42:53,870 across Lombok and on neighboring islands. 684 00:42:56,007 --> 00:42:58,241 They conduct geophysical surveys 685 00:42:58,276 --> 00:43:01,310 to measure the depth of the volcanic deposits 686 00:43:01,346 --> 00:43:03,846 still buried beneath the ground. 687 00:43:03,882 --> 00:43:05,882 And they investigate whether 688 00:43:05,917 --> 00:43:09,118 gases from this eruption could have reached high enough 689 00:43:09,154 --> 00:43:11,954 into the upper atmosphere to spread globally. 690 00:43:14,559 --> 00:43:16,526 KOMOROWSKI: To assess the scale of the eruption, 691 00:43:16,561 --> 00:43:18,728 we looked at these pumice fragments 692 00:43:18,763 --> 00:43:20,863 that were ejected by the eruption column. 693 00:43:24,102 --> 00:43:25,968 And the idea is that the further away 694 00:43:26,004 --> 00:43:28,704 you find big fragments, it means that these fragments 695 00:43:28,740 --> 00:43:30,506 were ejected with a lot of energy... 696 00:43:33,812 --> 00:43:34,844 ...and that the eruption column 697 00:43:34,879 --> 00:43:36,946 reached very high in the atmosphere. 698 00:43:39,818 --> 00:43:43,653 NARRATOR: In this case, pumice fragments two inches across 699 00:43:43,688 --> 00:43:48,291 were found 29 miles away on the nearby island of Sumbawa, 700 00:43:48,326 --> 00:43:52,461 allowing the team to calculate that the pumice likely ascended 701 00:43:52,497 --> 00:43:58,401 nearly 27 miles high-- more than ten miles higher 702 00:43:58,436 --> 00:44:00,703 than the Mount St. Helens eruption of 1980. 703 00:44:02,874 --> 00:44:05,308 KOMOROWSKI: This is one of the highest column heights 704 00:44:05,343 --> 00:44:08,177 for explosive eruptions in the last 10,000 years. 705 00:44:09,547 --> 00:44:11,848 NARRATOR: The Mount Samalas eruption 706 00:44:11,883 --> 00:44:15,751 was certainly massive enough to cool the entire world. 707 00:44:18,656 --> 00:44:21,891 But can scientific tests prove that the pumice 708 00:44:21,926 --> 00:44:24,927 was from the mystery 1257 eruption? 709 00:44:28,032 --> 00:44:32,768 In Paris, French volcanologist Celine Vidal goes through 710 00:44:32,804 --> 00:44:35,137 the samples taken from Indonesia. 711 00:44:39,010 --> 00:44:41,110 First, she selects pieces of carbonized wood 712 00:44:41,145 --> 00:44:47,116 found inside the pumice deposits for radiocarbon dating. 713 00:44:47,151 --> 00:44:50,086 (translated): We analyzed 20 pieces of carbonized wood 714 00:44:50,121 --> 00:44:51,487 from sites all across the volcano, 715 00:44:51,522 --> 00:44:55,258 and the carbon 14 dating told us that the eruption 716 00:44:55,293 --> 00:44:57,126 dated to the second half of the 13th century. 717 00:44:58,997 --> 00:45:00,963 LAVIGNE: All the results were consistent 718 00:45:00,999 --> 00:45:03,699 with the mystery eruption. 719 00:45:03,735 --> 00:45:07,536 NARRATOR: The dates are in range, 720 00:45:07,572 --> 00:45:09,538 but there is one final test. 721 00:45:09,574 --> 00:45:11,641 Will the chemical fingerprint of this eruption 722 00:45:11,676 --> 00:45:15,778 match the fingerprint in the polar ice cores? 723 00:45:19,250 --> 00:45:21,350 At high magnification, 724 00:45:21,386 --> 00:45:24,320 Vidal compares the volcanic ash fragments, 725 00:45:24,355 --> 00:45:28,190 one from the Antarctic ice core from 1257, 726 00:45:28,226 --> 00:45:35,097 and one from the pumice deposits on Lombok. 727 00:45:35,133 --> 00:45:36,699 (translated): You can see that the surfaces 728 00:45:36,734 --> 00:45:38,134 of the two different particles of ash 729 00:45:38,169 --> 00:45:42,405 have the same texture, and that their edges are very sharp. 730 00:45:42,440 --> 00:45:46,208 NARRATOR: They appear very similar. 731 00:45:46,244 --> 00:45:50,379 But how closely do their chemical fingerprints match? 732 00:45:50,415 --> 00:45:52,682 (translated): I add now the chemical composition of the ash 733 00:45:52,717 --> 00:45:56,218 from Samalas here in blue, 734 00:45:56,254 --> 00:46:01,090 and one sees that the peaks correspond perfectly. 735 00:46:01,125 --> 00:46:02,758 They are comparable to more than 99%, 736 00:46:02,794 --> 00:46:05,294 and that is really excellent. 737 00:46:05,330 --> 00:46:09,365 This allows us to conclude that they are from the same origin. 738 00:46:09,400 --> 00:46:14,103 NARRATOR: Now there is finally enough evidence to remove all doubt-- 739 00:46:14,138 --> 00:46:18,441 the mystery killer volcano is here on Lombok, 740 00:46:18,476 --> 00:46:22,878 Mount Samalas, once known and since forgotten. 741 00:46:22,914 --> 00:46:25,481 The team was very excited by the result. 742 00:46:25,516 --> 00:46:30,720 KOMOROWSKI: The source of the 1257 eruption has been a mystery for 30 years, 743 00:46:30,755 --> 00:46:34,490 so we were quite excited when we were able to prove 744 00:46:34,525 --> 00:46:38,361 that Mount Samalas erupted in 1257. 745 00:46:38,396 --> 00:46:42,732 NARRATOR: The mystery of the massive spike of sulphuric acid 746 00:46:42,767 --> 00:46:45,501 in the polar ice cores, the global volcanic winter 747 00:46:45,536 --> 00:46:48,971 caused by a cloud of aerosols that blocked the sun, 748 00:46:49,007 --> 00:46:53,209 and likely, the thousands of people killed in London 749 00:46:53,244 --> 00:46:58,014 in a catastrophic famine, all have been answered. 750 00:46:58,049 --> 00:46:59,949 By combining these discoveries 751 00:46:59,984 --> 00:47:02,618 with the investigation on the volcano, 752 00:47:02,653 --> 00:47:08,724 the team can now unpack the eruption blow by blow. 753 00:47:08,760 --> 00:47:12,695 The 1257 eruption started with a very explosive, 754 00:47:12,730 --> 00:47:16,966 violent eruption from Mount Samalas. 755 00:47:17,001 --> 00:47:19,502 NARRATOR: At its peak, the eruption blasted out 756 00:47:19,537 --> 00:47:24,507 one million tons of material a second. 757 00:47:24,542 --> 00:47:26,876 And that produced a very tall eruption column 758 00:47:26,911 --> 00:47:29,812 of ash and gases and pumice, 759 00:47:29,847 --> 00:47:33,049 rising 43 kilometers in elevation. 760 00:47:33,084 --> 00:47:36,719 NARRATOR: Nearly four cubic miles of pumice and ash 761 00:47:36,754 --> 00:47:40,689 rise four times higher than the operational altitude 762 00:47:40,725 --> 00:47:42,691 of a passenger jet. 763 00:47:42,727 --> 00:47:46,762 While the gases remain aloft, most of the pumice and ash 764 00:47:46,798 --> 00:47:49,198 then falls back to Earth. 765 00:47:49,233 --> 00:47:54,637 And it produced a rain of pumice over a very vast area. 766 00:47:54,672 --> 00:48:00,142 NARRATOR: It covers an area at least 450 miles across. 767 00:48:00,178 --> 00:48:04,480 During the final collapse of the volcano, 768 00:48:04,515 --> 00:48:06,816 six cubic miles of pumice and ash 769 00:48:06,851 --> 00:48:09,785 form giant pyroclastic flows. 770 00:48:09,821 --> 00:48:15,458 Racing down, they reach speeds of over 125 miles an hour, 771 00:48:15,493 --> 00:48:20,863 at temperatures of 1,500 degrees Fahrenheit. 772 00:48:20,898 --> 00:48:22,698 They covered the entire landscape of Lombok 773 00:48:22,733 --> 00:48:25,134 with thicknesses of five to 50 meters, 774 00:48:25,169 --> 00:48:28,504 reaching the sea in many places. 775 00:48:30,141 --> 00:48:34,543 NARRATOR: But even as the dust settles on Lombok, 776 00:48:34,579 --> 00:48:40,616 the vast volcanic cloud starts to envelop the entire world, 777 00:48:40,651 --> 00:48:43,319 even as far away from the eruption 778 00:48:43,354 --> 00:48:46,489 as North America and Europe. 779 00:48:46,524 --> 00:48:50,025 WALKER: The fact that we have so many thousands of people 780 00:48:50,061 --> 00:48:53,462 buried in these mass pits as a result 781 00:48:53,498 --> 00:48:54,997 of this volcanic eruption 782 00:48:55,032 --> 00:48:58,267 just shows us what a global event it was. 783 00:49:02,807 --> 00:49:06,175 NARRATOR: This was possibly the most massive volcanic eruption 784 00:49:06,210 --> 00:49:08,210 in recorded history. 785 00:49:10,014 --> 00:49:12,248 And it raises a troubling question. 786 00:49:12,283 --> 00:49:17,119 Could another eruption of this magnitude happen again? 787 00:49:17,155 --> 00:49:25,461 It's been 750 years since the giant eruption of Mount Samalas, 788 00:49:25,496 --> 00:49:28,864 yet inside its vast caldera, eruptions from Mount Barujari 789 00:49:28,900 --> 00:49:34,203 reveal that the volcanic system is still active. 790 00:49:38,976 --> 00:49:41,610 Two and a half thousand feet below the caldera rim, 791 00:49:41,646 --> 00:49:47,216 Komorowski rejoins the team of Indonesian volcanologists, 792 00:49:47,251 --> 00:49:49,985 monitoring the active heart 793 00:49:50,021 --> 00:49:52,488 of the Samalas/Rinjani volcanic complex. 794 00:50:05,102 --> 00:50:09,905 Using thermal imagery and making a risky trek 795 00:50:09,941 --> 00:50:11,840 to collect lava from the latest eruptions, 796 00:50:11,876 --> 00:50:14,443 the Indonesian volcanologists 797 00:50:14,478 --> 00:50:17,479 are gaining an ever more accurate picture 798 00:50:17,515 --> 00:50:22,051 of the volcano's activity level today. 799 00:50:22,086 --> 00:50:25,454 And the most telling clue to the volcano's activity 800 00:50:25,489 --> 00:50:27,022 is not the cone itself, 801 00:50:27,058 --> 00:50:31,193 but the rainwater lake that surrounds it. 802 00:50:35,099 --> 00:50:38,067 Volcanologist Devy Kamil Syahbana 803 00:50:38,102 --> 00:50:40,569 measures the water temperature. 804 00:50:42,573 --> 00:50:47,610 At an altitude 6,500 feet, more than a mile high, 805 00:50:47,645 --> 00:50:50,212 this lake should have a temperature 806 00:50:50,248 --> 00:50:53,816 of about 60 degrees Fahrenheit, or 15 degrees Celsius. 807 00:50:53,851 --> 00:50:57,519 DEVY KAMIL SYAHBANA: But here we have, like, 20 to 22 degrees Celsius, 808 00:50:57,555 --> 00:51:00,122 which is much hotter than a normal lake, 809 00:51:00,157 --> 00:51:03,425 which indicates a very strong magmatic activity 810 00:51:03,461 --> 00:51:06,128 beneath the caldera. 811 00:51:06,163 --> 00:51:09,298 NARRATOR: The eruption of 1257 812 00:51:09,333 --> 00:51:13,535 likely left a lot of magma behind, inside this chamber. 813 00:51:13,571 --> 00:51:15,938 The volcano is still under pressure, 814 00:51:15,973 --> 00:51:18,207 and it is still unstable. 815 00:51:18,242 --> 00:51:20,242 NARRATOR: The volcano remains active, 816 00:51:20,278 --> 00:51:21,810 but their analysis tells them 817 00:51:21,846 --> 00:51:24,346 that there is insufficient pressure 818 00:51:24,382 --> 00:51:28,350 to power a 1257-scale eruption. 819 00:51:28,386 --> 00:51:32,488 But what about other volcanoes? 820 00:51:32,523 --> 00:51:37,660 According to the ice core record, there have been at least 821 00:51:37,695 --> 00:51:40,496 seven explosive eruptions on the scale of Pinatubo 822 00:51:40,531 --> 00:51:44,166 near the equator since 1257. 823 00:51:44,201 --> 00:51:46,602 It will happen again. 824 00:51:46,637 --> 00:51:49,838 The worry is, no one knows when. 825 00:51:49,874 --> 00:51:53,609 KOMOROWSKI: If another major explosive eruption were to happen 826 00:51:53,644 --> 00:51:55,344 today in the equatorial region, 827 00:51:55,379 --> 00:51:57,513 it would have devastating consequences. 828 00:51:59,583 --> 00:52:01,050 There'll be huge disruption 829 00:52:01,085 --> 00:52:02,985 to global aviation. 830 00:52:03,020 --> 00:52:04,853 LAVIGNE: The economic impact would be 831 00:52:04,889 --> 00:52:05,721 really catastrophic. 832 00:52:08,092 --> 00:52:09,558 These massive volcanic events 833 00:52:09,593 --> 00:52:12,895 really impact on people globally. 834 00:52:12,930 --> 00:52:14,296 It affects their climate, 835 00:52:14,332 --> 00:52:16,265 food source, causes famine, 836 00:52:16,300 --> 00:52:20,202 and can cause catastrophic numbers of deaths. 837 00:52:21,739 --> 00:52:24,573 NARRATOR: 750 years ago, 838 00:52:24,608 --> 00:52:28,610 an eruption on a small island in Indonesia 839 00:52:28,646 --> 00:52:31,613 destroyed lives on the other side of the world, 840 00:52:31,649 --> 00:52:39,288 reminding us again of the power of our volatile Earth. 841 00:52:51,036 --> 00:52:53,703 This NOVA program is available on DVD. 842 00:52:53,738 --> 00:52:59,108 To order, visit shopPBS.org, or call 1-800-PLAY-PBS. 843 00:52:59,144 --> 00:53:01,277 NOVA is also available for download on iTunes. 68796

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