1 00:00:01,735 --> 00:00:04,336 (explosion) 2 00:00:04,404 --> 00:00:07,973 NARRATOR: Mount St. Helens-- the biggest volcanic eruption 3 00:00:08,041 --> 00:00:11,677 in North America in nearly a century. 4 00:00:13,446 --> 00:00:20,085 Virtually all life for 200 square miles is wiped out. 5 00:00:26,693 --> 00:00:29,895 It seems impossible that life could ever return 6 00:00:29,963 --> 00:00:32,865 to this barren wasteland. 7 00:00:32,932 --> 00:00:34,767 We found a lot of our conventional wisdom 8 00:00:34,834 --> 00:00:36,602 was just flat wrong. 9 00:00:36,669 --> 00:00:39,405 NARRATOR: In recent years there are ominous signs 10 00:00:39,472 --> 00:00:42,141 the volcano is awakening. 11 00:00:42,208 --> 00:00:44,143 MAN: These things were like skyscrapers that were being 12 00:00:44,210 --> 00:00:45,778 shoved out of the ground. 13 00:00:45,845 --> 00:00:47,212 They were literally that big. 14 00:00:51,584 --> 00:00:53,819 NARRATOR: A 30-year quest to understand 15 00:00:53,887 --> 00:00:57,256 one of the most complicated volcanoes in the world 16 00:00:57,323 --> 00:01:02,728 is revealing new mysteries deep inside the mountain. 17 00:01:02,796 --> 00:01:06,398 MAN: We don't know whether it's going to erupt explosively again 18 00:01:06,466 --> 00:01:14,706 in two years or in 20 years or in 200 years. 19 00:01:14,774 --> 00:01:18,343 NARRATOR: Is Mount St. Helens preparing to erupt again? 20 00:01:18,411 --> 00:01:23,015 Right now, on NOVA-- 21 00:01:23,083 --> 00:01:26,819 "Mount St. Helens: Back from the Dead." 22 00:01:42,001 --> 00:01:48,407 Major funding for NOVA is provided by the following... 23 00:01:48,475 --> 00:01:51,743 Supporting NOVA and promotingg public understanding of science. 24 00:01:54,781 --> 00:01:57,483 And the Corporation for Public Broadcasting, 25 00:01:57,550 --> 00:01:59,251 and by PBS viewers like you. 26 00:02:07,060 --> 00:02:10,062 NARRATOR: October 2004. 27 00:02:10,130 --> 00:02:13,565 Mount St. Helens comes back to life. 28 00:02:21,174 --> 00:02:27,412 Steam and ash spew from the crater on the mountain's summit. 29 00:02:27,480 --> 00:02:29,448 We saw the boiling material come out of the ground, 30 00:02:29,516 --> 00:02:31,517 we saw that it was blasting up, it was dark 31 00:02:31,584 --> 00:02:33,619 and it was light at the same time. 32 00:02:33,686 --> 00:02:36,421 It made a plume that rose up over the rim of the caldera. 33 00:02:36,489 --> 00:02:38,390 It came up to above our altitude, 34 00:02:38,458 --> 00:02:40,392 to 10,000 or 12,000 feet. 35 00:02:43,029 --> 00:02:45,397 NARRATOR: It's a frightening development. 36 00:02:45,465 --> 00:02:48,400 (explosion) 37 00:02:48,468 --> 00:02:51,570 For years, Mount St. Helens has been quiet. 38 00:02:51,638 --> 00:02:53,739 The volcano went from quiet to unrest to eruption 39 00:02:53,806 --> 00:02:55,607 very, very rapidly. 40 00:03:00,180 --> 00:03:03,615 NARRATOR: It could be headed for a massive explosion. 41 00:03:03,683 --> 00:03:05,417 DZURISIN: It seemed possible that we were headed 42 00:03:05,485 --> 00:03:07,753 toward an explosive eruption. 43 00:03:07,820 --> 00:03:09,188 We didn't know. 44 00:03:09,255 --> 00:03:11,690 That was a key question. 45 00:03:11,758 --> 00:03:13,492 NARRATOR: The effort to understand what is happening 46 00:03:13,560 --> 00:03:16,995 inside the mountain couldn't be more urgent. 47 00:03:17,063 --> 00:03:18,997 Is the volcano about to repeat the events 48 00:03:19,065 --> 00:03:22,434 of three decades earlier, when it shattered the tranquility 49 00:03:22,502 --> 00:03:24,436 of its peaceful surroundings? 50 00:03:30,510 --> 00:03:32,778 (bird screeches) 51 00:03:32,845 --> 00:03:36,381 NARRATOR: Spring 1980. 52 00:03:36,449 --> 00:03:40,052 Mount St. Helens is one of the major peaks 53 00:03:40,119 --> 00:03:42,287 in the Cascade Mountains. 54 00:03:45,892 --> 00:03:50,095 It's an area of outstanding beauty, rich in wildlife. 55 00:03:53,800 --> 00:03:58,604 For over 120 years, the volcano has been quiet. 56 00:03:58,671 --> 00:04:02,074 But in recent weeks it's been rumbling. 57 00:04:02,141 --> 00:04:06,345 Nobody is sure what to expect. 58 00:04:06,412 --> 00:04:09,715 Then, on May 18, 1980, 59 00:04:09,782 --> 00:04:14,853 a 5.1 magnitude earthquake rocks the mountain. 60 00:04:26,966 --> 00:04:29,334 Within ten seconds, 61 00:04:29,402 --> 00:04:31,870 the volcano's northern flank collapses 62 00:04:31,938 --> 00:04:34,906 in the largest landslide in recorded history. 63 00:04:37,443 --> 00:04:41,913 It releases millions of tons of magma in a colossal explosion. 64 00:04:47,387 --> 00:04:52,057 A cloud of searing gas and rock, known as a pyroclastic flow, 65 00:04:52,125 --> 00:04:54,993 races over the surrounding countryside. 66 00:05:00,300 --> 00:05:02,334 Forests are flattened. 67 00:05:10,810 --> 00:05:13,111 Four miles below the summit, 68 00:05:13,179 --> 00:05:17,115 an enormous lake is choked with debris. 69 00:05:25,425 --> 00:05:28,193 The eruption continues to shoot poisonous steam and ash 70 00:05:28,261 --> 00:05:30,662 miles into the air. 71 00:05:40,640 --> 00:05:43,208 It was just, again, astounding is the best word 72 00:05:43,276 --> 00:05:45,644 to describe what happened in 1980 here in Mount St. Helens. 73 00:05:51,851 --> 00:05:53,752 NARRATOR: The northern slope of the mountain is buried 74 00:05:53,820 --> 00:05:56,288 in several feet of ash. 75 00:06:05,498 --> 00:06:08,633 Virtually all life is extinguished. 76 00:06:13,272 --> 00:06:16,241 57 people are dead. 77 00:06:16,309 --> 00:06:22,314 They include loggers, campers, scientists and a reporter. 78 00:06:22,382 --> 00:06:28,186 Some are up to 13 miles away in areas considered safe. 79 00:06:32,024 --> 00:06:36,461 The plume of steam and ash rises miles into the sky 80 00:06:36,529 --> 00:06:38,296 for the rest of the day. 81 00:06:38,364 --> 00:06:41,066 The drifting ash cloud disrupts air traffic 82 00:06:41,134 --> 00:06:44,336 for hundreds of miles. 83 00:06:44,404 --> 00:06:49,074 The scale of the destruction is enormous. 84 00:06:55,448 --> 00:06:57,716 NARRATOR: Across more than 200 square miles, 85 00:06:57,784 --> 00:07:01,286 the surge of ash and rock incinerates trees. 86 00:07:07,794 --> 00:07:09,194 Thousands of birds 87 00:07:09,262 --> 00:07:13,031 from more than a hundred species disappear. 88 00:07:16,602 --> 00:07:20,439 Billions of insects are gone. 89 00:07:23,743 --> 00:07:27,012 Deer and elk are wiped out. 90 00:07:34,987 --> 00:07:38,723 This vast area of devastation becomes known as the blast 91 00:07:38,791 --> 00:07:40,592 or blow-down zone. 92 00:07:45,064 --> 00:07:48,633 Nearer the crater, ash and rocks from the landslide 93 00:07:48,701 --> 00:07:50,802 litter the northern slope of the mountain. 94 00:07:55,508 --> 00:07:57,943 It looks like the moon. 95 00:08:00,580 --> 00:08:02,681 It's called the pumice plain. 96 00:08:04,817 --> 00:08:06,852 It's directly below the crater. 97 00:08:10,089 --> 00:08:13,625 Four miles from the volcano, 98 00:08:13,693 --> 00:08:16,394 the enormous Spirit Lake is scarcely recognizable. 99 00:08:20,066 --> 00:08:24,402 The avalanche has lifted its bed more than 200 feet. 100 00:08:27,340 --> 00:08:30,675 The surface is smothered in dead trees. 101 00:08:30,743 --> 00:08:34,412 Hundreds of species of aquatic life, including insects, 102 00:08:34,480 --> 00:08:38,783 amphibians and fish, are killed. 103 00:08:38,851 --> 00:08:40,385 CHARLIE CRISAFULLI: It was black water. 104 00:08:40,453 --> 00:08:42,420 And it de-gassed and bubbled, 105 00:08:42,488 --> 00:08:44,689 and there were hot springs that were coming up. 106 00:08:44,757 --> 00:08:46,324 If you were to put your fingers 107 00:08:46,392 --> 00:08:49,160 in to your wrist and wiggle them, you wouldn't even be able 108 00:08:49,228 --> 00:08:50,395 to see your fingertips. 109 00:08:50,463 --> 00:08:53,365 That's how grossly modified the water was. 110 00:08:56,903 --> 00:08:58,637 NARRATOR: Mount St. Helens is now 111 00:08:58,704 --> 00:09:03,408 a lifeless jumble of shattered forest, rock and ash. 112 00:09:03,476 --> 00:09:07,379 It's hard to imagine life will ever return. 113 00:09:15,421 --> 00:09:17,255 The eruption was so powerful, 114 00:09:17,323 --> 00:09:19,925 it altered the shape of the mountain. 115 00:09:26,399 --> 00:09:30,135 Mount St. Helens was a typical cone-shaped volcano 116 00:09:30,202 --> 00:09:34,005 known as a stratovolcano. 117 00:09:37,677 --> 00:09:41,379 But the landslide has torn 1,300 feet off the summit, 118 00:09:41,447 --> 00:09:47,352 leaving a gaping crater a mile wide and 2,000 feet deep. 119 00:09:47,420 --> 00:09:50,822 It's the largest volcanic eruption in North America 120 00:09:50,890 --> 00:09:53,592 in nearly a century. 121 00:09:59,131 --> 00:10:02,567 (helicopter blades whirring) 122 00:10:02,635 --> 00:10:07,739 Weeks after the eruption, scientists arrive at the crater. 123 00:10:09,475 --> 00:10:12,477 The volcano is still steaming and rumbling. 124 00:10:12,545 --> 00:10:14,813 It's a new and unfamiliar world. 125 00:10:18,117 --> 00:10:21,553 One of the first to arrive is Dan Dzurisin. 126 00:10:21,621 --> 00:10:23,355 DZURISIN: There was a tremendous amount of steam 127 00:10:23,422 --> 00:10:26,124 and you could see that it was very hot. 128 00:10:26,192 --> 00:10:28,326 You didn't see red lava oozing out of the ground. 129 00:10:28,394 --> 00:10:31,196 You didn't see fantastic fire fountains. 130 00:10:31,263 --> 00:10:36,668 There was this constant background roar of rocks 131 00:10:36,736 --> 00:10:39,604 cascading down the crater walls. 132 00:10:39,672 --> 00:10:42,040 Occasionally a very large rock the size of the helicopter 133 00:10:42,108 --> 00:10:44,142 would come bouncing down and you could watch it 134 00:10:44,210 --> 00:10:47,812 and it was almost slow motion because the crater was so large. 135 00:10:47,880 --> 00:10:51,383 NARRATOR: Mount St. Helens has a long history of eruptions. 136 00:10:51,450 --> 00:10:56,054 More than 500 years ago, two massive explosions took place 137 00:10:56,122 --> 00:10:57,922 within two years of each other. 138 00:10:57,990 --> 00:11:00,825 They were nearly four times larger than May 1980. 139 00:11:02,895 --> 00:11:07,132 The mountain sits on one of the most active seismic zones 140 00:11:07,199 --> 00:11:11,336 in the world, the Pacific Ring of Fire-- 141 00:11:11,404 --> 00:11:15,740 a vast arc of volcanoes running for thousands of miles. 142 00:11:15,808 --> 00:11:18,910 It's home to some of the biggest and most dangerous volcanoes 143 00:11:18,978 --> 00:11:21,312 active today. 144 00:11:34,260 --> 00:11:37,462 Here, the enormous plates making up the earth's crust 145 00:11:37,530 --> 00:11:42,133 are being squeezed together. 146 00:11:43,035 --> 00:11:45,990 Along the coast, the plate below the Pacific 147 00:11:46,016 --> 00:11:48,559 is sliding un the North American plate. 148 00:11:48,659 --> 00:11:54,172 60 miles down pressure and friction melt the rock. 149 00:11:55,437 --> 00:11:57,938 Magma wells up. 150 00:11:58,006 --> 00:12:01,008 When it reaches the surface, it bursts out. 151 00:12:01,076 --> 00:12:03,611 (explosion) 152 00:12:10,585 --> 00:12:13,954 But there are still many unanswered questions. 153 00:12:16,891 --> 00:12:20,027 Scientists' understanding of what triggers an eruption 154 00:12:20,095 --> 00:12:22,696 this massive is incomplete. 155 00:12:22,764 --> 00:12:24,431 And given the scale of destruction, 156 00:12:24,499 --> 00:12:26,734 they need to find a way to predict 157 00:12:26,801 --> 00:12:30,738 when it might happen again before it's too late. 158 00:12:30,805 --> 00:12:33,140 Mount St. Helens is about to become 159 00:12:33,208 --> 00:12:37,811 one of the most intensely studied volcanoes in the world. 160 00:12:45,553 --> 00:12:49,523 The mysteries are not just geological. 161 00:12:49,591 --> 00:12:52,693 Biologists want to know if any life has survived 162 00:12:52,761 --> 00:12:54,395 and what its future will be. 163 00:13:00,001 --> 00:13:02,169 Charlie Crisafulli, one of the leading experts 164 00:13:02,237 --> 00:13:06,840 on the mountain's ecology, arrives soon after the eruption. 165 00:13:06,908 --> 00:13:09,443 CRISAFULLI: Nothing could have prepared me for the sights and sounds 166 00:13:09,511 --> 00:13:11,512 that I saw when I got here. 167 00:13:11,579 --> 00:13:17,484 It was complete and utter barrenness 168 00:13:17,552 --> 00:13:20,154 and there was no sign of life whatsoever. 169 00:13:20,221 --> 00:13:23,123 NARRATOR: His job is to survey the mountain, 170 00:13:23,191 --> 00:13:26,060 looking for any living things. 171 00:13:26,127 --> 00:13:29,730 CRISAFULLI: It was just intriguing to think about how would life come back 172 00:13:29,798 --> 00:13:30,798 to this landscape. 173 00:13:30,865 --> 00:13:32,032 What would the pattern be? 174 00:13:32,100 --> 00:13:33,867 How would the rate be? 175 00:13:37,172 --> 00:13:40,574 NARRATOR: Much of the mountain is still inaccessible. 176 00:13:40,642 --> 00:13:43,377 So he starts work in the blow-down zone 177 00:13:43,445 --> 00:13:46,980 in an area some eight miles downhill from the crater. 178 00:13:47,048 --> 00:13:52,519 CRISAFULLI: We flew over in a helicopter very close to the ground. 179 00:13:52,587 --> 00:13:54,888 We would have these bumping, twisting flights 180 00:13:54,956 --> 00:13:56,924 across the landscape following a contour. 181 00:14:01,296 --> 00:14:02,863 NARRATOR: In the first three months, 182 00:14:02,931 --> 00:14:05,866 there's nothing but dead and uprooted trees. 183 00:14:09,270 --> 00:14:11,438 Then he notices something... 184 00:14:14,509 --> 00:14:17,244 Signs of freshly disturbed earth. 185 00:14:21,950 --> 00:14:23,917 CRISAFULLI: Lo and behold, in many locations, 186 00:14:23,985 --> 00:14:26,754 brown earth on top of the gray volcanic ash. 187 00:14:28,490 --> 00:14:31,158 NARRATOR: Is there something down there? 188 00:14:31,226 --> 00:14:34,394 Crisafulli returns on foot to investigate. 189 00:14:42,270 --> 00:14:48,909 There, emerging from the ash, is a tiny burrowing animal. 190 00:14:48,977 --> 00:14:53,814 It's a northern pocket gopher. 191 00:14:53,882 --> 00:14:55,115 CRISAFULLI: It was very thrilling. 192 00:14:58,386 --> 00:15:02,589 NARRATOR: How can it possibly have survived when nothing else has? 193 00:15:06,461 --> 00:15:08,562 CRISAFULLI: This tiny animal lives entirely beneath the ground. 194 00:15:08,630 --> 00:15:10,731 And so when the blast occurred, 195 00:15:10,799 --> 00:15:12,766 it would have been safely protected 196 00:15:12,834 --> 00:15:14,568 beneath a mantle of soil 197 00:15:14,636 --> 00:15:17,738 and may very well have survived in many locations. 198 00:15:17,806 --> 00:15:22,075 NARRATOR: Over the following months, he finds more gophers. 199 00:15:24,212 --> 00:15:28,282 It appears that life is returning to the mountain 200 00:15:28,349 --> 00:15:30,784 just three months after the eruption. 201 00:15:37,525 --> 00:15:40,794 NARRATOR: By fall, the volcano is still active. 202 00:15:43,398 --> 00:15:45,265 Plumes of steam and ash 203 00:15:45,333 --> 00:15:48,035 continue to shoot thousands of feet into the air. 204 00:15:51,272 --> 00:15:54,341 But something else is happening, too. 205 00:15:54,409 --> 00:15:57,044 The crater floor appears to be moving. 206 00:15:58,980 --> 00:16:02,749 Is the mountain preparing for another major eruption? 207 00:16:02,817 --> 00:16:06,153 DZURISIN: We would sometimes notice a crack 208 00:16:06,221 --> 00:16:08,288 that hadn't been there the day before. 209 00:16:08,356 --> 00:16:11,024 And by the end of the day the crack was larger. 210 00:16:11,092 --> 00:16:13,794 And you realized that the ground was moving beneath your feet. 211 00:16:16,698 --> 00:16:19,032 NARRATOR: It's an unsettling experience 212 00:16:19,100 --> 00:16:23,270 to stand on the floor of a volcano that's visibly moving. 213 00:16:26,541 --> 00:16:30,110 If you stood and looked very, very, very carefully, 214 00:16:30,178 --> 00:16:31,645 with a reference point in the background, 215 00:16:31,713 --> 00:16:34,982 sometimes you could see it move, but just barely. 216 00:16:35,049 --> 00:16:40,888 NARRATOR: The scientists set up a time- lapse camera on a nearby ridge. 217 00:16:49,030 --> 00:16:52,499 Over several days, the pictures show a dome 218 00:16:52,567 --> 00:16:55,569 rising in the middle of the crater floor. 219 00:16:55,637 --> 00:17:00,374 The volcano is oozing a sticky gray lava, 220 00:17:00,441 --> 00:17:03,744 cooling as it reaches the surface. 221 00:17:10,451 --> 00:17:14,288 Over several months, the dome grows larger. 222 00:17:21,129 --> 00:17:23,297 The geologists are puzzled. 223 00:17:23,364 --> 00:17:25,966 What is going on inside the mountain? 224 00:17:26,034 --> 00:17:28,802 Is Mount St. Helens simply rebuilding its summit 225 00:17:28,870 --> 00:17:31,238 or is it about to blow up? 226 00:17:31,306 --> 00:17:34,675 DZURISIN: We didn't know what might come next, 227 00:17:34,742 --> 00:17:36,944 whether the lava might continue to grow for many years-- 228 00:17:37,011 --> 00:17:38,712 or even decades or centuries-- 229 00:17:38,780 --> 00:17:40,280 and we didn't know if there might be 230 00:17:40,348 --> 00:17:42,649 explosive eruptions in store. 231 00:17:44,719 --> 00:17:47,287 NARRATOR: Then winter closes in, 232 00:17:47,355 --> 00:17:49,623 restricting access to the mountain. 233 00:17:51,893 --> 00:17:54,995 The scientists' work is limited. 234 00:17:55,063 --> 00:17:58,098 Answers will have to wait until spring. 235 00:18:11,312 --> 00:18:13,547 (bird singing) 236 00:18:13,614 --> 00:18:19,519 Spring 1981, nearly a year after the initial eruption. 237 00:18:19,587 --> 00:18:22,723 Life returns to the hills and valleys of the Cascade Range. 238 00:18:23,925 --> 00:18:25,792 But on Mount St. Helens, 239 00:18:25,860 --> 00:18:29,329 the devastation of the previous year is still obvious. 240 00:18:32,367 --> 00:18:33,867 Despite the danger, 241 00:18:33,935 --> 00:18:37,337 Crisafulli moves closer to the active volcano's core. 242 00:18:40,808 --> 00:18:45,312 The pumice plain is buried in several feet of coarse ash. 243 00:18:47,015 --> 00:18:50,150 It's a dusty, barren wilderness. 244 00:18:50,218 --> 00:18:54,454 Life seems impossible. 245 00:18:54,522 --> 00:18:57,624 CRISAFULLI: This is an area where super-hot incandescent flows came down 246 00:18:57,692 --> 00:18:59,326 and killed all life that was here. 247 00:19:04,399 --> 00:19:08,235 NARRATOR: Helicopter is the only way in. 248 00:19:08,302 --> 00:19:10,337 CRISAFULLI: We were flying back and forth, very low, 249 00:19:10,405 --> 00:19:13,206 just above the ground surface, looking for any form of life. 250 00:19:16,077 --> 00:19:21,048 NARRATOR: He crisscrosses the area but there's nothing to see. 251 00:19:21,115 --> 00:19:27,954 Then suddenly, amidst the acres of barren rock, 252 00:19:28,022 --> 00:19:32,325 there's an unexpected flash of color. 253 00:19:32,393 --> 00:19:36,096 CRISAFULLI: So we set the helicopter down and we walked up. 254 00:19:36,164 --> 00:19:40,400 Right out in the center of the pumice plain we saw a plant. 255 00:19:42,070 --> 00:19:45,872 NARRATOR: At first, Crisafulli can hardly believe his eyes. 256 00:19:45,940 --> 00:19:48,608 It was a prairie lupine, a species that typically grows 257 00:19:48,676 --> 00:19:52,112 high in the slopes of Mount St. Helens. 258 00:19:52,180 --> 00:19:56,750 NARRATOR: It's not only growing, it's flourishing. 259 00:19:56,818 --> 00:19:59,219 CRISAFULLI: Not only had the plant established, 260 00:19:59,287 --> 00:20:02,122 but at that point was in full flower. 261 00:20:02,190 --> 00:20:04,024 And it was quite remarkable. 262 00:20:04,092 --> 00:20:06,460 When we saw the first one we were very surprised. 263 00:20:08,429 --> 00:20:11,331 NARRATOR: It's only four miles from the volcano's crater. 264 00:20:11,399 --> 00:20:14,067 It's the first sign of life 265 00:20:14,135 --> 00:20:17,170 in an area where everything has been extinguished. 266 00:20:21,309 --> 00:20:24,744 But how has the plant managed to grow in such a barren area? 267 00:20:24,812 --> 00:20:27,948 The answer is a special root structure 268 00:20:28,015 --> 00:20:30,817 that provides its own fertilizer. 269 00:20:30,885 --> 00:20:35,489 These are little factories where a bacterium works with the plant 270 00:20:35,556 --> 00:20:39,192 and provides nitrogen to the plant. 271 00:20:39,260 --> 00:20:45,665 In return the plant provides the bacterium with simple sugars 272 00:20:45,733 --> 00:20:48,368 that it fixes through photosynthesis. 273 00:20:48,436 --> 00:20:50,370 And so this is a great relationship 274 00:20:50,438 --> 00:20:52,606 where you scratch my back, I'll scratch yours. 275 00:20:56,811 --> 00:20:59,513 NARRATOR: This special process means lupines can grow 276 00:20:59,580 --> 00:21:03,016 in even the most inhospitable terrain. 277 00:21:03,084 --> 00:21:05,819 The lupine, like the gopher Charlie found earlier, 278 00:21:05,887 --> 00:21:08,622 is a pioneering species. 279 00:21:08,689 --> 00:21:10,257 CRISAFULLI: It's really important 280 00:21:10,324 --> 00:21:12,025 in landscapes like Mount St. Helens, 281 00:21:12,093 --> 00:21:14,294 because the volcanic material that fell on the ground 282 00:21:14,362 --> 00:21:16,730 tends to be really nutrient poor. 283 00:21:21,202 --> 00:21:22,869 NARRATOR: The conditions are difficult, 284 00:21:22,937 --> 00:21:26,940 but can the lupine pave the way for other life to follow? 285 00:21:35,650 --> 00:21:39,452 NARRATOR: In the spring, geologists also return to the mountain. 286 00:21:39,520 --> 00:21:42,222 During the winter months, 287 00:21:42,290 --> 00:21:45,158 lava has continued to ooze out of the crater floor. 288 00:21:49,197 --> 00:21:52,065 The lava dome has grown several hundred feet taller 289 00:21:52,133 --> 00:21:55,535 and doubled in diameter. 290 00:21:58,472 --> 00:22:01,341 It's still a hazardous place. 291 00:22:01,409 --> 00:22:03,410 DZURISIN: When I stepped out of the helicopter in 1981 292 00:22:03,477 --> 00:22:05,278 on the crater floor, 293 00:22:05,346 --> 00:22:08,215 steam was actively rising off the growing lava dome. 294 00:22:13,321 --> 00:22:15,388 There was still a tremendous amount of noise. 295 00:22:18,826 --> 00:22:20,260 Rock falls were constant... 296 00:22:20,328 --> 00:22:24,464 and 2,000 feet above your head 297 00:22:24,532 --> 00:22:26,700 used to be where the summit of the volcano was. 298 00:22:31,405 --> 00:22:33,740 You were now standing in a crater with a lava dome 299 00:22:33,808 --> 00:22:35,709 that had not been there a few months previously 300 00:22:35,776 --> 00:22:37,644 or a year previously. 301 00:22:37,712 --> 00:22:40,213 It was actively steaming. 302 00:22:40,281 --> 00:22:44,884 That was a very... very exciting thought. 303 00:22:47,054 --> 00:22:50,390 NARRATOR: It's a rare opportunity to watch the process of dome building 304 00:22:50,458 --> 00:22:52,525 unfold in front of their eyes. 305 00:22:56,530 --> 00:22:59,065 The geologists set up instruments to monitor 306 00:22:59,133 --> 00:23:01,434 what's going on, 307 00:23:01,502 --> 00:23:05,772 including seismometers that can detect tremors set off by lava 308 00:23:05,840 --> 00:23:09,409 as it forces its way through the rocks. 309 00:23:09,477 --> 00:23:13,480 They place a series of these as close to the lava dome 310 00:23:13,547 --> 00:23:15,782 as possible. 311 00:23:19,520 --> 00:23:21,688 (birds chirping) 312 00:23:21,756 --> 00:23:24,090 At the Cascades Volcano Observatory 313 00:23:24,158 --> 00:23:28,495 in southern Washington, the seismic data pours in. 314 00:23:31,332 --> 00:23:34,668 DZURISIN: The seismic record like this 315 00:23:34,735 --> 00:23:36,803 records any vibration of the ground... 316 00:23:39,373 --> 00:23:42,742 so we can see real rock-breaking earthquakes, 317 00:23:42,810 --> 00:23:44,010 we can see rock falls. 318 00:23:44,078 --> 00:23:45,745 (rumbling) 319 00:23:48,382 --> 00:23:49,749 It's our job to try to understand 320 00:23:49,817 --> 00:23:51,084 what all those signals mean 321 00:23:51,152 --> 00:23:54,287 in terms of what the volcano might do. 322 00:23:54,355 --> 00:23:57,590 NARRATOR: The first traces reflect extreme activity. 323 00:23:59,794 --> 00:24:01,828 DZURISIN: Here you see the record is almost continuous-- 324 00:24:01,896 --> 00:24:04,497 one earthquake after the other-- bang, bang, bang. 325 00:24:07,101 --> 00:24:08,968 The seismic signal is essentially continuous. 326 00:24:14,275 --> 00:24:16,710 NARRATOR: The lava is breaking through rocks 327 00:24:16,777 --> 00:24:18,912 and flowing across the crater floor. 328 00:24:22,616 --> 00:24:27,220 Then, the seismic record reveals a cyclical pattern. 329 00:24:33,661 --> 00:24:35,795 For periods of weeks to months, 330 00:24:35,863 --> 00:24:39,399 earthquake activity in the crater would be pretty quiet. 331 00:24:39,467 --> 00:24:43,136 NARRATOR: The lava is no longer flowing. 332 00:24:43,204 --> 00:24:45,972 DZURISIN: And then a few days later, we might see a pattern like this, 333 00:24:46,040 --> 00:24:48,742 more and more of these very sharp earthquakes. 334 00:24:50,411 --> 00:24:53,513 NARRATOR: It's the sign of lava on the move again, 335 00:24:53,581 --> 00:24:55,782 forcing its way through the round. 336 00:25:01,889 --> 00:25:04,858 DZURISIN: Eventually lava would make it on to the surface, 337 00:25:04,925 --> 00:25:06,726 maybe in just a couple of days, 338 00:25:06,794 --> 00:25:09,462 and we're seeing a continuous record of ground shaking, 339 00:25:09,530 --> 00:25:10,697 both earthquakes and rock falls. 340 00:25:20,608 --> 00:25:24,010 Then, after a period of dome growth 341 00:25:24,078 --> 00:25:31,384 that might last a few days or a few weeks, it goes quiet again. 342 00:25:31,452 --> 00:25:35,588 That episode has ended and the pattern begins itself over. 343 00:25:38,926 --> 00:25:41,694 NARRATOR: This cycle of dome building continues 344 00:25:41,762 --> 00:25:43,463 for the next five years. 345 00:25:46,667 --> 00:25:49,869 The pattern is so regular that when the cycle begins, 346 00:25:49,937 --> 00:25:52,205 the scientists can accurately predict 347 00:25:52,273 --> 00:25:54,674 what the volcano will do next. 348 00:25:57,278 --> 00:25:59,646 When the first rock-breaking earthquakes occur, 349 00:25:59,713 --> 00:26:02,482 they know it's only a matter of days or weeks 350 00:26:02,550 --> 00:26:06,119 before the lava starts to flow again. 351 00:26:06,187 --> 00:26:10,857 At one point the dome reaches nearly 1,000 feet-- 352 00:26:10,925 --> 00:26:13,660 almost as high as the Empire State Building. 353 00:26:16,163 --> 00:26:23,570 Then, in late 1986, the seismographs go quiet. 354 00:26:32,546 --> 00:26:33,780 DZURISIN: It was pretty clear 355 00:26:33,848 --> 00:26:36,749 that that period of dome building had ended. 356 00:26:36,817 --> 00:26:39,686 NARRATOR: But for how long? 357 00:26:39,753 --> 00:26:42,288 Has the mountain gone back to sleep? 358 00:26:42,356 --> 00:26:45,558 JON MAJOR: It wasn't clear whether the mountain had gone back to sleep 359 00:26:45,626 --> 00:26:47,060 now for centuries 360 00:26:47,127 --> 00:26:50,029 or whether it was going to just go back to sleep 361 00:26:50,097 --> 00:26:51,331 for a couple of years. 362 00:26:53,267 --> 00:26:55,735 NARRATOR: It seems the pattern has changed. 363 00:26:58,339 --> 00:27:00,907 For six years the scientists have been able to predict 364 00:27:00,975 --> 00:27:02,976 what the mountain will do next. 365 00:27:05,513 --> 00:27:12,452 Now they are back to guessing if and when it will erupt again. 366 00:27:18,959 --> 00:27:22,495 But even if the volcano has gone to sleep, 367 00:27:22,563 --> 00:27:25,465 the wildlife continues to bounce back. 368 00:27:30,905 --> 00:27:33,973 More and more gophers are spreading across 369 00:27:34,041 --> 00:27:36,142 the blow-down zone. 370 00:27:38,779 --> 00:27:41,814 Lupines are colonizing the pumice plain. 371 00:27:44,451 --> 00:27:48,922 And what's happening at Spirit Lake is remarkable. 372 00:27:52,927 --> 00:27:56,596 The May 1980 eruption obliterated all visible life 373 00:27:56,664 --> 00:27:57,830 in the lake. 374 00:27:57,898 --> 00:28:01,868 The surface was smothered in a blanket of debris. 375 00:28:03,671 --> 00:28:07,574 In the murky water there was an explosion of bacteria. 376 00:28:10,277 --> 00:28:12,245 CRISAFULLI: There were a couple of species of pneumonia 377 00:28:12,313 --> 00:28:13,513 that were described, 378 00:28:13,581 --> 00:28:15,181 and also the disease... 379 00:28:15,249 --> 00:28:17,383 the bacteria that causes Legionnaires Disease, 380 00:28:17,451 --> 00:28:19,018 legionella. 381 00:28:19,086 --> 00:28:21,654 And so, many of us working in the lakes in the early days 382 00:28:21,722 --> 00:28:22,855 came down with a fever. 383 00:28:24,858 --> 00:28:28,328 NARRATOR: The bacteria rapidly consumed the oxygen, 384 00:28:28,395 --> 00:28:31,831 making life impossible for any air-breathing organisms, 385 00:28:31,899 --> 00:28:35,602 including fish, amphibians and insects. 386 00:28:41,375 --> 00:28:43,209 We said it's going to be decades and decades 387 00:28:43,277 --> 00:28:45,979 before this resembles anything like a typical lake 388 00:28:46,046 --> 00:28:48,715 in the Cascade Mountain Range. 389 00:28:48,782 --> 00:28:50,516 Well, we were surprised, 390 00:28:50,584 --> 00:28:52,085 because that's not exactly what happened. 391 00:28:56,857 --> 00:29:00,493 NARRATOR: Scientists begin routine water sampling. 392 00:29:05,432 --> 00:29:09,502 It's a unique opportunity to see if and when life will return 393 00:29:09,570 --> 00:29:11,437 from the dead. 394 00:29:15,075 --> 00:29:18,044 At first there's nothing. 395 00:29:18,112 --> 00:29:24,350 But as the debris settles, the water clears. 396 00:29:24,418 --> 00:29:27,220 Light levels improve. 397 00:29:27,287 --> 00:29:31,391 Then, three years after the eruption, 398 00:29:31,458 --> 00:29:35,061 there's a crucial discovery... 399 00:29:35,129 --> 00:29:38,798 microscopic plants. 400 00:29:40,734 --> 00:29:46,572 They're phytoplankton-- plants that turn sunlight into oxygen. 401 00:29:50,077 --> 00:29:54,213 They've been brought in by birds or blown in by the wind. 402 00:29:54,281 --> 00:29:58,885 They are the basic building block of aquatic life. 403 00:30:01,588 --> 00:30:03,656 Over the following months, 404 00:30:03,724 --> 00:30:05,625 as light levels continue to improve, 405 00:30:05,693 --> 00:30:08,695 the plankton population grows. 406 00:30:08,762 --> 00:30:12,065 CRISAFULLI: In fact, between 1983 and 1986, 407 00:30:12,132 --> 00:30:15,702 135 different species of these tiny plants 408 00:30:15,769 --> 00:30:18,371 had colonized the lake. 409 00:30:18,439 --> 00:30:23,976 They provide the oxygen and also the prey for the food web. 410 00:30:24,044 --> 00:30:27,780 NARRATOR: Sunlight, oxygen and food. 411 00:30:27,848 --> 00:30:31,150 Several years after its complete destruction, 412 00:30:31,218 --> 00:30:35,421 Spirit Lake is coming back to life. 413 00:30:41,328 --> 00:30:45,131 Four miles away, the volcano remains quiet. 414 00:30:45,199 --> 00:30:49,368 The lava dome has stopped growing. 415 00:30:49,436 --> 00:30:53,239 Many geologists think the show is over, 416 00:30:53,307 --> 00:30:56,142 at least in their lifetime. 417 00:30:56,210 --> 00:30:59,579 We had the feeling that we had probably seen our last eruption 418 00:30:59,646 --> 00:31:01,214 of Mount St. Helens. 419 00:31:01,281 --> 00:31:03,850 We knew there was a chance it would erupt again. 420 00:31:03,917 --> 00:31:06,919 But none of us were betting on it. 421 00:31:06,987 --> 00:31:11,724 NARRATOR: As the mountain sleeps, wildlife bounces back... 422 00:31:14,728 --> 00:31:17,697 even in the most unexpected places. 423 00:31:17,765 --> 00:31:20,066 In one of the most devastated areas of the mountain-- 424 00:31:20,134 --> 00:31:24,170 the pumice plain-- a gopher is seen. 425 00:31:28,075 --> 00:31:29,909 It's surviving by eating lupine. 426 00:31:36,350 --> 00:31:38,184 Lupines provide the food. 427 00:31:38,252 --> 00:31:40,052 Gophers enrich the pumice 428 00:31:40,120 --> 00:31:42,655 by burrowing their way through the ash. 429 00:31:42,723 --> 00:31:48,561 They mix in fresh soil and help new plants to spread. 430 00:31:58,105 --> 00:32:01,207 CRISAFULLI: When you walked around the landscape, it was those islands 431 00:32:01,275 --> 00:32:03,743 created by gopher-turned soils that were very green 432 00:32:03,811 --> 00:32:05,645 and full of flower and seeds. 433 00:32:07,714 --> 00:32:13,085 NARRATOR: The gophers also play another role in helping wildlife spread. 434 00:32:13,153 --> 00:32:17,657 Crisafulli finds a salamander in a gopher's tunnel. 435 00:32:17,724 --> 00:32:20,626 CRISAFULLI: What's interesting about the gopher is they create 436 00:32:20,694 --> 00:32:22,862 kilometers of underground tunnel systems. 437 00:32:25,332 --> 00:32:27,667 NARRATOR: Elk are returning to the area, 438 00:32:27,734 --> 00:32:32,438 helping to expand this amazing web of life. 439 00:32:38,979 --> 00:32:41,147 CRISAFULLI: When elk move across the landscape, 440 00:32:41,215 --> 00:32:45,251 they collapse the tunnels, creating entranceways 441 00:32:45,319 --> 00:32:48,421 that salamanders and other amphibians can get access to. 442 00:32:48,488 --> 00:32:50,923 And once they get beneath the ground, 443 00:32:50,991 --> 00:32:53,092 these are very cool and moist sites that enable them 444 00:32:53,160 --> 00:32:55,494 to survive in an otherwise inhospitable area. 445 00:32:58,432 --> 00:33:01,100 And the importance of that is that it allows them to use 446 00:33:01,168 --> 00:33:04,303 these underground burrows as stepping stones 447 00:33:04,371 --> 00:33:06,873 during hot, dry weather and eventually to colonize 448 00:33:06,940 --> 00:33:09,475 new patches of terrestrial habitat 449 00:33:09,543 --> 00:33:11,711 as well as ponds and lakes. 450 00:33:13,847 --> 00:33:15,181 (frog croaking) 451 00:33:21,288 --> 00:33:25,458 NARRATOR: Spirit Lake now teems with amphibians. 452 00:33:28,929 --> 00:33:33,633 Fish, brought to the lake by fishermen, are thriving, 453 00:33:33,700 --> 00:33:35,801 a clear indication that the water quality 454 00:33:35,869 --> 00:33:38,037 is returning to normal. 455 00:33:38,105 --> 00:33:41,340 CRISAFULLI: What's happened with the fish was actually remarkable. 456 00:33:41,408 --> 00:33:42,909 While we don't have a good handle 457 00:33:42,976 --> 00:33:45,711 on the total number of fish, we know from our snorkeling 458 00:33:45,779 --> 00:33:49,415 and surveys that the population is enormous. 459 00:33:55,689 --> 00:33:57,690 NARRATOR: Spirit Lake is beginning to resemble 460 00:33:57,758 --> 00:34:00,726 a typical mountain lake. 461 00:34:00,794 --> 00:34:04,697 Just over a decade after the eruption, 462 00:34:04,765 --> 00:34:09,735 life is flooding back to the slopes of Mount St. Helens. 463 00:34:09,803 --> 00:34:11,704 The rate of recovery is far faster 464 00:34:11,772 --> 00:34:14,307 than anybody had expected. 465 00:34:14,374 --> 00:34:19,078 CRISAFULLI: Clearly our understanding of the ability of these organisms 466 00:34:19,146 --> 00:34:23,582 to disperse was greatly underappreciated. 467 00:34:23,650 --> 00:34:25,618 We found a lot of our conventional wisdom 468 00:34:25,686 --> 00:34:27,353 was just flat wrong. 469 00:34:27,421 --> 00:34:29,522 (birds chirping) 470 00:34:33,060 --> 00:34:37,430 NARRATOR: Then, as life recovers, new threats emerge. 471 00:34:40,367 --> 00:34:42,668 In September 2004, 472 00:34:42,736 --> 00:34:45,237 the seismographs at the Cascades Volcano Observatory 473 00:34:45,305 --> 00:34:48,307 pick up a new series of tremors 474 00:34:48,375 --> 00:34:50,910 deep below Mount St. Helens. 475 00:34:50,978 --> 00:34:53,846 The volcano has woken up. 476 00:34:55,949 --> 00:34:59,785 John Pallister takes a helicopter to investigate. 477 00:34:59,853 --> 00:35:02,855 PALLISTER: You could see the absolute beginning of the eruptions, 478 00:35:02,923 --> 00:35:05,424 unusual-- really unusual-- to just happen to be there, 479 00:35:05,492 --> 00:35:06,592 in a helicopter, 480 00:35:06,660 --> 00:35:09,328 the crater rim, on the upwind side, 481 00:35:09,396 --> 00:35:11,931 so the plume was going away from us. 482 00:35:11,999 --> 00:35:17,036 NARRATOR: Pallister has no idea how big this eruption will be. 483 00:35:17,104 --> 00:35:20,406 PALLISTER: We saw the boiling material come out of the ground. 484 00:35:20,474 --> 00:35:22,842 We saw that it was blasting up. 485 00:35:22,909 --> 00:35:25,411 It was dark ash coming out and light steam coming out 486 00:35:25,479 --> 00:35:26,912 at the same time. 487 00:35:30,584 --> 00:35:33,753 It made a plume that rose up over the rim of the caldera 488 00:35:33,820 --> 00:35:36,155 and drifted downwind. 489 00:35:36,223 --> 00:35:38,357 NARRATOR: The speed and suddenness of the eruption 490 00:35:38,425 --> 00:35:41,327 catches everybody by surprise. 491 00:35:41,395 --> 00:35:44,163 The volcano went from quiet to unrest to eruption 492 00:35:44,231 --> 00:35:45,765 very, very rapidly. 493 00:35:45,832 --> 00:35:48,567 (explosions) 494 00:35:56,009 --> 00:35:58,544 NARRATOR: During the next two weeks, there are three more eruptions 495 00:35:58,612 --> 00:36:01,313 of steam and ash. 496 00:36:01,381 --> 00:36:04,417 No one knows what will happen next. 497 00:36:04,484 --> 00:36:05,918 DZURISIN: It seemed possible 498 00:36:05,986 --> 00:36:09,221 that we were headed toward an explosive eruption. 499 00:36:09,289 --> 00:36:10,623 We didn't know. 500 00:36:10,690 --> 00:36:12,324 That was a key question. 501 00:36:14,261 --> 00:36:18,364 NARRATOR: Then, after 14 days, the seismographs quiet down. 502 00:36:22,702 --> 00:36:27,339 Almost as quickly as it started, the eruption stops. 503 00:36:32,746 --> 00:36:34,580 But then something strange happens. 504 00:36:38,018 --> 00:36:40,286 Over the next few weeks, the seismographs pick up 505 00:36:40,353 --> 00:36:42,154 a new pattern of tremors 506 00:36:42,222 --> 00:36:44,557 the geologists have never seen before. 507 00:36:52,365 --> 00:36:55,134 Could they be linked to a gigantic lump of lava 508 00:36:55,202 --> 00:36:56,802 growing out of the crater floor? 509 00:36:59,840 --> 00:37:04,477 PALLISTER: It was a huge kind of recumbent spine, 510 00:37:04,544 --> 00:37:07,546 this big mass lying in the crater floor 511 00:37:07,614 --> 00:37:09,648 some 300 meters or so high. 512 00:37:09,716 --> 00:37:14,887 NARRATOR: The spine of lava is as long as the Eiffel Tower. 513 00:37:14,955 --> 00:37:18,090 MAJOR: Everybody was just awestruck. 514 00:37:18,158 --> 00:37:20,960 To have this large spine just shoving up out of the ground 515 00:37:21,027 --> 00:37:23,295 was completely different and outside the experience 516 00:37:23,363 --> 00:37:25,131 of any of us here in the staff. 517 00:37:28,235 --> 00:37:34,273 NARRATOR: Despite the risk, John Pallister goes in to take samples. 518 00:37:34,341 --> 00:37:36,342 PALLISTER: We landed right next to it. 519 00:37:39,746 --> 00:37:42,281 And I was able to get out, helicopter helmet on, 520 00:37:42,349 --> 00:37:45,184 rapidly run up to the edge of the spine. 521 00:37:45,252 --> 00:37:48,687 NARRATOR: It's an unbelievable sight. 522 00:37:51,391 --> 00:37:56,695 DZURISIN: Had someone suggested to me that we make a movie 523 00:37:56,763 --> 00:38:00,132 of a lava dome growing that way, I think I would have said 524 00:38:00,200 --> 00:38:02,301 it's a little too fantastic, let's make it more realistic. 525 00:38:07,641 --> 00:38:09,341 NARRATOR: At the observatory, 526 00:38:09,409 --> 00:38:11,377 where geologists have been puzzling over 527 00:38:11,444 --> 00:38:18,784 the strange seismic traces, they now realize what they are. 528 00:38:18,852 --> 00:38:22,054 They're the unique autograph of the giant spines 529 00:38:22,122 --> 00:38:24,990 as they push their way out of the ground. 530 00:38:30,297 --> 00:38:34,300 DZURISIN: This is the seismic signature of solid blocks of rock 531 00:38:34,367 --> 00:38:36,502 grinding their way through the volcano, 532 00:38:36,570 --> 00:38:40,206 coming out onto the surface. 533 00:38:40,273 --> 00:38:44,410 As they do, they make these small seismic signals, 534 00:38:44,477 --> 00:38:48,514 one just like the other, just like the other, very repetitive. 535 00:38:48,582 --> 00:38:51,984 We came to call them "drumbeats." 536 00:38:52,052 --> 00:38:55,521 NARRATOR: The drumbeats continue for several years. 537 00:38:55,589 --> 00:39:01,594 Spine after spine of solid lava emerges from the crater floor. 538 00:39:01,661 --> 00:39:06,165 It's unlike anything geologists have seen on Mount St. Helens. 539 00:39:06,233 --> 00:39:08,500 PALLISTER: Now, spine doesn't do justice to these things. 540 00:39:08,568 --> 00:39:10,135 These things were like skyscrapers 541 00:39:10,203 --> 00:39:11,737 that were being shoved out of the ground. 542 00:39:11,805 --> 00:39:12,871 They were literally that big. 543 00:39:15,041 --> 00:39:19,178 NARRATOR: Sometimes the blocks grow at a rate of 16 feet a day. 544 00:39:22,148 --> 00:39:24,550 Then they collapse. 545 00:39:28,154 --> 00:39:31,190 Seen through a time-lapse camera, 546 00:39:31,258 --> 00:39:34,059 one solid lump of lava after another 547 00:39:34,127 --> 00:39:36,495 pushes up through the crater floor. 548 00:39:40,333 --> 00:39:42,534 The process is mystifying. 549 00:39:42,602 --> 00:39:45,904 What do the spines mean? 550 00:39:45,972 --> 00:39:49,041 Why was the eruption in 2004 so different 551 00:39:49,109 --> 00:39:51,076 than the style of eruption in the 1980s? 552 00:39:53,480 --> 00:39:57,149 Why in the 1980s did you have this more fluid lava 553 00:39:57,217 --> 00:40:00,653 that created the sort of short, stubby lava flows 554 00:40:00,720 --> 00:40:02,388 that came out and built the lava dome? 555 00:40:05,659 --> 00:40:08,427 Whereas in 2004, you basically had solid rock being pushed up 556 00:40:08,495 --> 00:40:10,029 in the ground. 557 00:40:10,096 --> 00:40:12,865 NARRATOR: There's one urgent question. 558 00:40:12,932 --> 00:40:16,969 Is the volcano building up to another major eruption? 559 00:40:17,037 --> 00:40:20,472 MAJOR: Trying to make sense of what was going on was a challenge. 560 00:40:20,540 --> 00:40:23,275 Trying to understand how the eruption was going to progress 561 00:40:23,343 --> 00:40:25,511 was a challenge. 562 00:40:25,578 --> 00:40:27,579 We had lots of discussions about whether or not 563 00:40:27,647 --> 00:40:29,581 it was going to be an explosive eruption, 564 00:40:29,649 --> 00:40:31,550 whether it was going to be another dome building eruption. 565 00:40:36,156 --> 00:40:39,625 NARRATOR: There is one way to find out. 566 00:40:39,693 --> 00:40:43,362 Analyzing samples of the lava might explain 567 00:40:43,430 --> 00:40:48,867 the mysterious solid blocks and what they mean for the future. 568 00:40:54,341 --> 00:40:58,544 At the volcano observatory, John Pallister compares lava 569 00:40:58,611 --> 00:41:02,648 from the spines with samples taken from previous eruptions. 570 00:41:05,051 --> 00:41:07,152 Could there be something in their composition 571 00:41:07,220 --> 00:41:11,590 that explains why the mountain sometimes pushes up spines... 572 00:41:13,827 --> 00:41:17,262 sometimes oozes lava... 573 00:41:19,933 --> 00:41:23,369 and sometimes explodes? 574 00:41:23,436 --> 00:41:25,404 (rumbling) 575 00:41:29,542 --> 00:41:32,144 Pallister begins with a sample of the lava 576 00:41:32,212 --> 00:41:35,748 that erupted so explosively in May 1980. 577 00:41:35,815 --> 00:41:40,386 He's immediately struck by the large areas of blue. 578 00:41:40,453 --> 00:41:44,223 PALLISTER: Okay, so what's important about this 1980 rock 579 00:41:44,290 --> 00:41:49,094 is the abundance of this blue area, which... 580 00:41:49,162 --> 00:41:51,330 and that's basically bubbles. 581 00:41:51,398 --> 00:41:53,732 Now, that's not a mineral; 582 00:41:53,800 --> 00:41:55,768 that's just open space in the thin section. 583 00:41:55,835 --> 00:41:57,369 That's where gas bubbles were. 584 00:41:57,437 --> 00:42:00,406 This sample would float in water, it had so much gas in it. 585 00:42:02,409 --> 00:42:07,112 NARRATOR: The gas comes from water, a component of the magma. 586 00:42:07,180 --> 00:42:08,947 As magma rises, 587 00:42:09,015 --> 00:42:12,618 changes in pressure turn the water into gas. 588 00:42:12,685 --> 00:42:15,554 The gas pressurizes the magma. 589 00:42:15,622 --> 00:42:19,591 It's what gives volcanoes their explosive force. 590 00:42:19,659 --> 00:42:22,027 (explosions) 591 00:42:22,228 --> 00:42:25,130 PALLISTER: 1980 had a lot of gas in it. 592 00:42:25,198 --> 00:42:27,032 So it exploded, tore itself apart 593 00:42:27,100 --> 00:42:29,368 in a tremendous explosive eruption. 594 00:42:36,776 --> 00:42:40,679 NARRATOR: But when he looks at lava taken from the 1983 period 595 00:42:40,747 --> 00:42:43,916 of dome building, it's different. 596 00:42:46,753 --> 00:42:50,322 PALLISTER: There is much less of this open space, 597 00:42:50,390 --> 00:42:54,059 of the gas filling space in the rock. 598 00:42:54,127 --> 00:42:59,998 NARRATOR: The 1983 lava behaves like a bottle of soda going flat. 599 00:43:02,936 --> 00:43:05,204 Finally he looks at a sample of lava 600 00:43:05,271 --> 00:43:08,407 from one of the spines in 2005. 601 00:43:08,475 --> 00:43:10,509 PALLISTER: I don't see any blue space, 602 00:43:10,577 --> 00:43:12,344 any of that-- oh, there's just a little bit-- 603 00:43:12,412 --> 00:43:16,615 but dominantly it is... it is lacking in space. 604 00:43:16,683 --> 00:43:21,286 It's a gas-poor magma... in fact almost none. 605 00:43:24,190 --> 00:43:27,893 NARRATOR: There's just enough gas to push it to the surface. 606 00:43:27,961 --> 00:43:31,096 But by the time it gets there, there's nothing left. 607 00:43:31,164 --> 00:43:32,865 PALLISTER: So this one came up slow 608 00:43:32,932 --> 00:43:37,936 and it made sticky, solidified spines instead of making 609 00:43:38,004 --> 00:43:39,938 either lava flows or an explosive eruption. 610 00:43:43,076 --> 00:43:45,043 NARRATOR: It's a crucial insight. 611 00:43:45,111 --> 00:43:47,679 The amount of gas determines the nature of the lava 612 00:43:47,747 --> 00:43:50,549 and the force of the eruption. 613 00:43:50,617 --> 00:43:56,021 PALLISTER: It all comes down to the gas budget for the eruption. 614 00:43:56,089 --> 00:44:00,893 Is it going to fizzle or is it going to explode? 615 00:44:02,695 --> 00:44:06,832 NARRATOR: Suddenly the mountain's behavior makes sense. 616 00:44:06,900 --> 00:44:10,068 The spines are a sign the magma under Mount St. Helens 617 00:44:10,136 --> 00:44:13,572 is running low on gas. 618 00:44:13,640 --> 00:44:19,945 Then, in 2007, as if to confirm this new insight, 619 00:44:20,013 --> 00:44:26,018 the familiar drumbeat seismic traces... 620 00:44:26,085 --> 00:44:27,819 vanish completely. 621 00:44:30,757 --> 00:44:34,159 No more spines appear. 622 00:44:34,227 --> 00:44:39,565 The lava below the mountain has finally run out of gas. 623 00:44:45,004 --> 00:44:47,239 How long will it take the mountain to build up 624 00:44:47,307 --> 00:44:50,208 enough gas pressure for another eruption? 625 00:44:54,681 --> 00:44:56,048 I think that's the most important question 626 00:44:56,115 --> 00:44:57,616 we have to answer. 627 00:44:57,684 --> 00:45:00,719 How long does it take to build up the gas necessary 628 00:45:00,787 --> 00:45:02,821 to drive an explosive eruption? 629 00:45:02,889 --> 00:45:07,159 NARRATOR: That's now the question they need to answer. 630 00:45:16,703 --> 00:45:20,405 Geologists go back to the mountain to look for clues. 631 00:45:25,178 --> 00:45:30,048 The eruption in 1980 took the top off Mount St. Helens, 632 00:45:30,116 --> 00:45:34,019 leaving its history exposed in the rock walls of the crater. 633 00:45:41,394 --> 00:45:43,929 Most of the important previous eruptions are marked 634 00:45:43,997 --> 00:45:47,032 by different colored bands. 635 00:45:47,100 --> 00:45:49,568 The lower part of the walls where you see gray 636 00:45:49,636 --> 00:45:53,738 and some yellows and some pinks 637 00:45:53,740 --> 00:45:56,942 are all part of the older edifice of Mount St. Helens. 638 00:45:59,779 --> 00:46:03,782 NARRATOR: These rocks, which make up the bottom half of the rock face, 639 00:46:03,850 --> 00:46:06,952 are around 16,000 years old. 640 00:46:07,020 --> 00:46:10,656 MAJOR: Then, if you look higher on the wall, near the top, 641 00:46:10,723 --> 00:46:14,426 you see darker colors. 642 00:46:14,494 --> 00:46:16,261 And those are rocks that began erupting 643 00:46:16,329 --> 00:46:20,065 about 3,000 to 2,500 years ago. 644 00:46:25,038 --> 00:46:27,239 So, by looking at what we call the stratigraphy 645 00:46:27,241 --> 00:46:29,941 in this magnificent exposure of the rock types 646 00:46:30,009 --> 00:46:33,812 in the crater walls, we can piece back the puzzle 647 00:46:33,880 --> 00:46:36,648 and understand the history as far as eruptive activity 648 00:46:36,716 --> 00:46:39,217 of Mount St. Helens. 649 00:46:39,285 --> 00:46:43,722 NARRATOR: Do the rocks give any indication how long it takes to build up 650 00:46:43,790 --> 00:46:46,358 enough gas between eruptions 651 00:46:46,426 --> 00:46:48,860 for the sleepy mountain to awake again? 652 00:46:55,802 --> 00:46:58,437 John Pallister sorts and categorizes rocks 653 00:46:58,504 --> 00:47:02,274 from earlier eruptions. 654 00:47:02,341 --> 00:47:06,244 He checks notes and photos to try and determine 655 00:47:06,312 --> 00:47:10,582 how often the mountain has erupted violently. 656 00:47:10,650 --> 00:47:12,517 Drawing on previous records, 657 00:47:12,585 --> 00:47:16,621 he builds up a picture of Mount St. Helens' past. 658 00:47:16,689 --> 00:47:19,357 For much of the last 4,000 years, 659 00:47:19,425 --> 00:47:22,928 there seems to be a fairly clear pattern. 660 00:47:22,995 --> 00:47:24,963 If we look at the number of big eruptions 661 00:47:25,031 --> 00:47:27,566 over the length of time the volcano's been active, 662 00:47:27,633 --> 00:47:29,868 you might say that there's one roughly every thousand years, 663 00:47:29,936 --> 00:47:31,436 a big eruption. 664 00:47:31,504 --> 00:47:34,306 So from our context here we could say 665 00:47:34,373 --> 00:47:36,508 that it takes on the order of a thousand years 666 00:47:36,576 --> 00:47:39,177 to build up enough gas to get a really large eruption. 667 00:47:43,149 --> 00:47:48,386 NARRATOR: The record suggests some of these eruptions have been huge, 668 00:47:48,454 --> 00:47:53,558 more than ten times larger than 1980, 669 00:47:53,626 --> 00:47:59,765 potentially enveloping vast areas of Washington and Oregon. 670 00:47:59,832 --> 00:48:02,968 But that would imply that the next really big one isn't due 671 00:48:03,035 --> 00:48:04,936 for about another century. 672 00:48:08,040 --> 00:48:12,210 Except for one little detail around 500 years ago. 673 00:48:14,347 --> 00:48:17,215 PALLISTER: In 1479 A.D. and 1482 674 00:48:17,283 --> 00:48:18,517 there were two very large eruptions. 675 00:48:18,584 --> 00:48:20,986 (explosions) 676 00:48:25,391 --> 00:48:28,960 So the volcano is capable of surprising us and producing 677 00:48:29,028 --> 00:48:30,362 two highly explosive eruptions 678 00:48:30,429 --> 00:48:32,130 in a span of less than three years. 679 00:48:32,198 --> 00:48:37,736 NARRATOR: Both these eruptions were much bigger than May 1980. 680 00:48:37,804 --> 00:48:40,338 There is no straightforward pattern. 681 00:48:42,608 --> 00:48:45,343 Mount St. Helens can pause for a thousand years 682 00:48:45,411 --> 00:48:50,615 between big explosive eruptions, or it can pause for three. 683 00:48:53,319 --> 00:48:56,521 These results have left geologists with one certainty 684 00:48:56,589 --> 00:48:58,657 and a number of questions. 685 00:49:00,359 --> 00:49:02,994 First of all, we expect this volcano to erupt again 686 00:49:03,062 --> 00:49:04,629 as repeatedly in the past; 687 00:49:04,697 --> 00:49:07,065 there's no reason to think it's gone to sleep forever now. 688 00:49:09,869 --> 00:49:12,370 NARRATOR: There will be another eruption, 689 00:49:12,438 --> 00:49:18,944 but nobody can determine when or just how big it will be. 690 00:49:19,011 --> 00:49:22,614 PALLISTER: We don't know whether it's going to erupt explosively again 691 00:49:22,682 --> 00:49:26,885 n two years or in 20 years or in 200 years. 692 00:49:26,953 --> 00:49:30,655 That's an area that needs a lot more work, 693 00:49:30,723 --> 00:49:32,357 a lot more research to understand 694 00:49:32,425 --> 00:49:35,794 and it is of fundamental importance to being able 695 00:49:35,862 --> 00:49:38,063 to forecast and to save lives and to save property. 696 00:49:47,473 --> 00:49:49,708 (bird screeches) 697 00:49:53,880 --> 00:49:57,282 NARRATOR: For 30 years, Mount St. Helens has led scientists 698 00:49:57,350 --> 00:50:01,519 on an extraordinary journey of surprise and discovery. 699 00:50:01,587 --> 00:50:06,591 When they surveyed the destruction in the early 1980s, 700 00:50:06,659 --> 00:50:09,261 nobody could have predicted the speed with which 701 00:50:09,328 --> 00:50:11,730 life has returned. 702 00:50:11,797 --> 00:50:13,665 CRISAFULLI: It was another form of an eruption, 703 00:50:13,733 --> 00:50:16,468 it was an eruption of nature. 704 00:50:16,535 --> 00:50:18,370 Nature marched back with a vengeance. 705 00:50:21,540 --> 00:50:25,844 NARRATOR: Mount St. Helens has revealed a rich and complex web of life 706 00:50:25,912 --> 00:50:29,281 that has never been documented before. 707 00:50:29,348 --> 00:50:32,384 Today the slopes of the mountain are a living testimony 708 00:50:32,451 --> 00:50:38,623 to the miraculous ability of nature to return from the dead. 709 00:50:38,691 --> 00:50:40,992 CRISAFULLI: Each time you would come out here 710 00:50:41,060 --> 00:50:43,728 and there would be a surprise, something would be unveiled, 711 00:50:43,796 --> 00:50:45,897 something that you hadn't seen before. 712 00:50:45,965 --> 00:50:47,966 Perhaps it would be a new species of spider 713 00:50:48,034 --> 00:50:49,267 or a new species of beetle. 714 00:50:54,540 --> 00:50:56,741 Nature is very resilient, 715 00:50:56,809 --> 00:50:58,610 and that is the take-home message from 30 years 716 00:50:58,678 --> 00:51:01,813 of ecological work on the Mount St. Helens volcano. 717 00:51:07,219 --> 00:51:12,991 NARRATOR: But as nature bounces back, the mountain still broods overhead. 718 00:51:15,127 --> 00:51:18,430 It's like a ticking time bomb waiting to destroy life 719 00:51:18,497 --> 00:51:22,267 all over again. 720 00:51:22,335 --> 00:51:24,536 MAJOR: Based on the history of this volcano, 721 00:51:24,603 --> 00:51:26,538 we know it's been extremely active 722 00:51:26,605 --> 00:51:29,341 and it's not a matter of whether, if it will erupt again, 723 00:51:29,408 --> 00:51:31,242 it's a matter of when it will erupt again, 724 00:51:31,310 --> 00:51:35,146 when will it reactivate, when will it reawaken. 725 00:51:35,214 --> 00:51:39,851 NARRATOR: These are questions scientists are still wrestling with. 726 00:51:39,919 --> 00:51:42,620 DZURISIN: We have yet to find a silver bullet, 727 00:51:42,688 --> 00:51:47,225 a magic thing that we can measure that tells us 728 00:51:47,293 --> 00:51:49,227 when the volcano is going to turn on. 729 00:51:50,529 --> 00:51:55,000 NARRATOR: Mount St. Helens will erupt again. 730 00:51:55,067 --> 00:52:00,905 The only questions are when and how big that eruption will be. 731 00:52:28,234 --> 00:52:30,001 On NOVA's "Mount St. Helens" Web site, 732 00:52:30,069 --> 00:52:32,904 go behind the scenes with director Daniel Hissen. 733 00:52:32,972 --> 00:52:34,506 See stunning images 734 00:52:34,573 --> 00:52:37,509 of the landscape's remarkable return to life, and more. 735 00:52:37,576 --> 00:52:39,110 Find it on pbs.org. 736 00:52:40,746 --> 00:52:43,515 Captioned by Media Access Group at WGBH access.wgbh.org 737 00:52:57,897 --> 00:53:02,567 This NOVA program is available on DVD at shopPBS.org, 738 00:53:02,635 --> 00:53:05,870 or call 1-800-play-PBS.