1 00:00:02,991 --> 00:00:05,989 >> Earth, a 4.5-billion-year- 2 00:00:05,990 --> 00:00:09,787 old planet, still evolving. 3 00:00:09,788 --> 00:00:12,588 As continents shift and clash, 4 00:00:12,623 --> 00:00:15,889 volcanoes erupt, and glaciers 5 00:00:15,955 --> 00:00:18,223 grow and recede, the Earth's 6 00:00:18,257 --> 00:00:20,122 crust is carved in numerous 7 00:00:20,157 --> 00:00:22,224 and fascinating ways, leaving 8 00:00:22,259 --> 00:00:23,557 a trail of geological 9 00:00:23,625 --> 00:00:26,891 mysteries behind. 10 00:00:26,958 --> 00:00:28,424 In this episode, an 11 00:00:28,527 --> 00:00:29,726 investigation into 12 00:00:29,760 --> 00:00:31,592 California's San Andreas 13 00:00:31,660 --> 00:00:34,226 Fault, the greatest fault line 14 00:00:34,294 --> 00:00:38,227 on Earth. 800 miles long, this 15 00:00:38,295 --> 00:00:40,394 ugly scar on the landscape has 16 00:00:40,462 --> 00:00:42,494 spawned Earthquake after 17 00:00:42,562 --> 00:00:45,362 Earthquake. 18 00:00:45,396 --> 00:00:47,029 But, for now, it waits 19 00:00:47,096 --> 00:00:49,029 quietly, deep under our 20 00:00:49,131 --> 00:00:51,931 cities, building up stress to 21 00:00:51,999 --> 00:00:53,664 strike once again. 22 00:00:56,566 --> 00:00:58,832 The San Andreas Fault is one of 23 00:00:58,934 --> 00:01:00,766 the most dangerous geological 24 00:01:00,834 --> 00:01:03,467 features on Earth. 25 00:01:05,466 --> 00:01:09,463 S01x01 San Andreas Fault Original Air Date on February 10, 2009 26 00:01:14,036 --> 00:01:15,669 California's greatest cities 27 00:01:15,737 --> 00:01:17,103 and millions of her citizens 28 00:01:17,171 --> 00:01:19,838 live in constant peril. 29 00:01:24,006 --> 00:01:25,572 Since records began, there 30 00:01:25,639 --> 00:01:27,739 have been 13 large Earthquakes 31 00:01:27,806 --> 00:01:31,207 along the San Andreas Fault. 32 00:01:31,275 --> 00:01:32,207 >> Reporter: The water lines 33 00:01:32,275 --> 00:01:33,374 have ruptured, there is no 34 00:01:33,408 --> 00:01:34,741 water coming out of the fire 35 00:01:34,808 --> 00:01:36,007 hydrants. 36 00:01:36,074 --> 00:01:37,207 >> And now, America's 37 00:01:37,275 --> 00:01:38,742 geologists, her rock 38 00:01:38,809 --> 00:01:40,375 detectives, are warning of 39 00:01:40,442 --> 00:01:42,743 a potential disaster. 40 00:01:42,844 --> 00:01:43,910 >> Reporter: The major damage 41 00:01:43,944 --> 00:01:47,109 has been done. 42 00:01:47,178 --> 00:01:49,377 >> In the fall of 2008, more 43 00:01:49,444 --> 00:01:51,811 than 300 scientists calculated 44 00:01:51,846 --> 00:01:53,546 what a major Earthquake would do 45 00:01:53,647 --> 00:01:55,178 to Southern California. 46 00:01:57,846 --> 00:01:59,180 >> We've been conducting a 47 00:01:59,214 --> 00:02:00,647 special study of a magnitude 48 00:02:00,747 --> 00:02:02,647 7.8 Earthquake on the southern 49 00:02:02,748 --> 00:02:03,813 San Andreas Fault, large 50 00:02:03,915 --> 00:02:05,381 enough to potentially damage 51 00:02:05,448 --> 00:02:06,748 tall buildings. Fire will be 52 00:02:06,815 --> 00:02:09,381 very significant. 53 00:02:09,448 --> 00:02:10,649 >> The definitive scientific 54 00:02:10,750 --> 00:02:11,749 report presented to 55 00:02:11,816 --> 00:02:13,384 politicians was codenamed 56 00:02:13,450 --> 00:02:16,449 Shakeout. It forecast 57 00:02:16,551 --> 00:02:17,884 thousands of deaths and 58 00:02:17,919 --> 00:02:19,385 nillions of dollars of damage 59 00:02:19,452 --> 00:02:22,518 in the city of Los Angeles, 60 00:02:22,553 --> 00:02:23,817 which makes it crucial to 61 00:02:23,886 --> 00:02:25,653 investigate the most important 62 00:02:25,720 --> 00:02:28,786 question--when will the next 63 00:02:28,820 --> 00:02:30,920 big Earthquake hit the San 64 00:02:30,987 --> 00:02:32,888 Andreas Fault? 65 00:02:37,189 --> 00:02:38,422 The latest preparations for 66 00:02:38,456 --> 00:02:39,989 disaster are the climax of an 67 00:02:40,024 --> 00:02:41,422 investigation that started 68 00:02:41,456 --> 00:02:46,724 more than 100 years ago, in 69 00:02:46,791 --> 00:02:48,191 the aftermath of the great San 70 00:02:48,292 --> 00:02:50,925 Francisco Earthquake of 1906. 71 00:02:54,626 --> 00:02:55,991 The Earthquake struck on a 72 00:02:56,060 --> 00:02:58,326 wednesday, just before dawn. 73 00:03:00,727 --> 00:03:02,360 The ground shook violently for 74 00:03:02,428 --> 00:03:04,694 45 seconds, igniting fires 75 00:03:04,728 --> 00:03:06,361 that raged unchecked for the 76 00:03:06,429 --> 00:03:08,261 next four days. 77 00:03:13,531 --> 00:03:15,997 28,000 buildings, a tenth of 78 00:03:16,065 --> 00:03:17,231 the entire city, were 79 00:03:17,265 --> 00:03:19,465 destroyed, and more than 3,000 80 00:03:19,533 --> 00:03:21,464 people, one in every hundred 81 00:03:21,532 --> 00:03:22,631 of the population, were 82 00:03:22,732 --> 00:03:24,799 killed. With a magnitude of 83 00:03:24,900 --> 00:03:27,266 7.8, it's in the top 20 of 84 00:03:27,335 --> 00:03:29,267 North America's strongest ever 85 00:03:29,368 --> 00:03:31,167 Earthquakes. 86 00:03:32,703 --> 00:03:34,168 The scale of the great San 87 00:03:34,268 --> 00:03:35,535 Francisco Earthquake shocked 88 00:03:35,636 --> 00:03:39,070 the nation. But no one 89 00:03:39,170 --> 00:03:40,871 understood what had made the 90 00:03:40,904 --> 00:03:42,903 city shake. 91 00:03:47,871 --> 00:03:48,905 Native American myths 92 00:03:49,005 --> 00:03:50,171 explained Earthquakes as 93 00:03:50,239 --> 00:03:51,806 shocks from a battle between 94 00:03:51,873 --> 00:03:54,972 warring spirits. Latter-day 95 00:03:55,074 --> 00:03:56,407 explorers couldn't understand 96 00:03:56,440 --> 00:03:58,240 the shocks that destroyed 97 00:03:58,274 --> 00:03:59,808 their mission buildings. 98 00:04:01,908 --> 00:04:03,508 One spanish missionary wrote-- 99 00:04:03,542 --> 00:04:04,508 >> 100 00:04:04,542 --> 00:04:06,342 >> "The Earth shook around me 101 00:04:06,376 --> 00:04:08,242 from explosions under the 102 00:04:08,343 --> 00:04:11,344 ground." 103 00:04:11,444 --> 00:04:13,344 300 years later, and science 104 00:04:13,445 --> 00:04:14,643 has still made little 105 00:04:14,711 --> 00:04:16,545 progress. Refugees in the 106 00:04:16,580 --> 00:04:18,212 ruins of San Francisco still 107 00:04:18,279 --> 00:04:19,346 blamed Earthquake on 108 00:04:19,447 --> 00:04:20,812 mysterious underground 109 00:04:20,880 --> 00:04:22,412 explosions. 110 00:04:26,448 --> 00:04:28,180 So, just three days after the 111 00:04:28,248 --> 00:04:29,514 Earthquake, the state of 112 00:04:29,582 --> 00:04:30,981 California asked one of the 113 00:04:31,049 --> 00:04:31,982 world's most famous 114 00:04:32,083 --> 00:04:34,149 Geologists, Andrew Lawson from 115 00:04:34,217 --> 00:04:35,982 California State University, 116 00:04:36,083 --> 00:04:37,416 to investigate what had 117 00:04:37,450 --> 00:04:39,217 destroyed the city. 118 00:04:41,152 --> 00:04:43,717 He and a team of 25 scientists 119 00:04:43,785 --> 00:04:45,051 began collecting damage 120 00:04:45,085 --> 00:04:46,352 evidence in the city and 121 00:04:46,420 --> 00:04:48,885 surrounding countryside. 122 00:04:48,953 --> 00:04:50,219 There were roads that had 123 00:04:50,253 --> 00:04:53,421 buckled. Rail tracks that had 124 00:04:53,521 --> 00:04:56,386 twisted the most startling 125 00:04:56,487 --> 00:04:59,121 evidence of all? That came 126 00:04:59,222 --> 00:05:00,722 near the town of Bolinas in 127 00:05:00,756 --> 00:05:01,854 Marin county, to the 128 00:05:01,922 --> 00:05:05,022 North of San Francisco. This 129 00:05:05,123 --> 00:05:06,756 picket fence had an eight-foot 130 00:05:06,824 --> 00:05:09,923 gap in the middle. Before the 131 00:05:09,958 --> 00:05:11,258 earthquake, it was a solid 132 00:05:11,358 --> 00:05:12,959 boundary fence, dividing 133 00:05:12,993 --> 00:05:16,258 two fields. But, when he 134 00:05:16,359 --> 00:05:17,892 recreated what had happened, 135 00:05:17,993 --> 00:05:19,459 Lawson realized that the land 136 00:05:19,527 --> 00:05:21,692 had jolted apart and torn the 137 00:05:21,726 --> 00:05:23,360 fence in two. 138 00:05:26,462 --> 00:05:27,962 Plotting the evidence on a map 139 00:05:27,995 --> 00:05:29,895 around San Francisco revealed 140 00:05:29,996 --> 00:05:34,263 a surprising pattern, because 141 00:05:34,331 --> 00:05:36,430 connecting the dots drew a 142 00:05:36,464 --> 00:05:39,530 straight line, and, at every 143 00:05:39,631 --> 00:05:42,364 point, the Earth moved in the 144 00:05:42,432 --> 00:05:44,599 same way. On the coast to the 145 00:05:44,633 --> 00:05:47,733 North, inland to the South. 146 00:05:47,801 --> 00:05:49,332 This line of weakness was the 147 00:05:49,366 --> 00:05:51,367 culprit they were searching for. 148 00:05:53,535 --> 00:05:54,801 South of San Francisco, 149 00:05:54,868 --> 00:05:56,068 the suspect line ran 150 00:05:56,135 --> 00:05:57,968 underneath a lake, the Laguna 151 00:05:58,002 --> 00:06:00,536 De San Andreas. So now, the 152 00:06:00,637 --> 00:06:02,535 earthquake perpetrator at last 153 00:06:02,603 --> 00:06:06,170 had a name. Professor Lawson, 154 00:06:06,271 --> 00:06:07,504 who, a decade earlier, had 155 00:06:07,539 --> 00:06:08,903 identified cracks in the Earth 156 00:06:08,971 --> 00:06:11,238 here as a harmless rift, now 157 00:06:11,272 --> 00:06:13,339 rechristened it the San 158 00:06:13,440 --> 00:06:14,906 Andreas Fault. 159 00:06:18,441 --> 00:06:20,074 In modern-day San Francisco, 160 00:06:20,175 --> 00:06:21,341 the buildings, the roads and 161 00:06:21,408 --> 00:06:22,907 the railways have long since 162 00:06:22,975 --> 00:06:25,140 been repaired. But, if you 163 00:06:25,175 --> 00:06:26,675 know where to look, evidence 164 00:06:26,709 --> 00:06:28,942 of the 1906 quake can still be 165 00:06:28,977 --> 00:06:30,442 found. 166 00:06:32,510 --> 00:06:33,943 Geologist Charlie Paull 167 00:06:33,978 --> 00:06:35,245 follows in the footsteps of 168 00:06:35,344 --> 00:06:37,044 Lawson's team, seeking signs 169 00:06:37,078 --> 00:06:39,778 of the havoc from 1906. 170 00:06:42,512 --> 00:06:43,978 He finds it on the cliffs at 171 00:06:44,080 --> 00:06:46,312 Mussel rock, 12 miles south of 172 00:06:46,347 --> 00:06:47,780 San Francisco. 173 00:06:47,881 --> 00:06:49,714 >> The cliff is not here by 174 00:06:49,780 --> 00:06:51,046 accident, there's a very good 175 00:06:51,081 --> 00:06:52,680 reason why this cliff is here. 176 00:06:52,715 --> 00:06:54,514 Half a mile or so of the shore 177 00:06:54,582 --> 00:06:56,348 face apparently fell off in 178 00:06:56,415 --> 00:06:58,215 the 1906 Earthquake, and if you 179 00:06:58,250 --> 00:06:59,616 look down below us, there's a 180 00:06:59,683 --> 00:07:01,950 big rotated block, um, that's 181 00:07:01,985 --> 00:07:03,350 near the present-day shoreline, 182 00:07:03,417 --> 00:07:06,517 and it is just inboard 183 00:07:06,585 --> 00:07:07,951 of the San Andreas Fault, the 184 00:07:07,986 --> 00:07:09,252 San Andreas Fault is, uh, 185 00:07:09,318 --> 00:07:10,418 about a quarter of a mile 186 00:07:10,485 --> 00:07:11,585 offshore here, and of course, 187 00:07:11,619 --> 00:07:13,219 that's one of the major 188 00:07:13,254 --> 00:07:15,885 crustal junctions, um, on 189 00:07:15,953 --> 00:07:17,486 this side of North America. 190 00:07:21,322 --> 00:07:22,854 >> Modern computers can now 191 00:07:22,888 --> 00:07:24,788 trace how damage waves spread 192 00:07:24,888 --> 00:07:26,955 out across the city. And that 193 00:07:27,057 --> 00:07:28,422 pinpoints where the quake 194 00:07:28,490 --> 00:07:30,022 originated along the San 195 00:07:30,056 --> 00:07:31,523 Andreas. 196 00:07:35,592 --> 00:07:37,224 It was offshore, about two 197 00:07:37,292 --> 00:07:38,658 miles out to sea from the 198 00:07:38,692 --> 00:07:40,325 Golden Gate Bridge. 199 00:07:42,027 --> 00:07:43,592 So, to continue tracking the 200 00:07:43,660 --> 00:07:45,493 fault, the investigation must 201 00:07:45,527 --> 00:07:48,928 head out to sea. Marine 202 00:07:48,962 --> 00:07:50,494 Geologists use remote 203 00:07:50,562 --> 00:07:51,794 operating vehicles, 204 00:07:51,862 --> 00:07:53,428 mini-submarines, to map the 205 00:07:53,496 --> 00:07:55,395 sea floor. 206 00:07:55,463 --> 00:07:56,929 >> What you would see is 207 00:07:56,997 --> 00:07:58,096 subtle variations in the 208 00:07:58,197 --> 00:07:59,563 topgraphy, or topography that 209 00:07:59,664 --> 00:08:02,364 would not naturally line up. 210 00:08:02,465 --> 00:08:04,163 So there might be a line on 211 00:08:04,198 --> 00:08:05,665 the ocean floor that is higher 212 00:08:05,732 --> 00:08:07,732 or lower on one side, and you 213 00:08:07,799 --> 00:08:10,032 can use various techniques to 214 00:08:10,100 --> 00:08:11,465 determine that this actually 215 00:08:11,566 --> 00:08:13,199 is a fault, instead of some 216 00:08:13,300 --> 00:08:15,200 other process. 217 00:08:15,302 --> 00:08:16,567 >> Running south across the 218 00:08:16,635 --> 00:08:18,101 seabed, the San Andreas 219 00:08:18,168 --> 00:08:20,167 finally runs out of ocean, and 220 00:08:20,202 --> 00:08:23,268 hits the land. This broken 221 00:08:23,370 --> 00:08:24,935 line of rocks, stretching in 222 00:08:25,003 --> 00:08:26,435 from the sea, marks where the 223 00:08:26,470 --> 00:08:28,203 San Andreas hits land, 12 224 00:08:28,271 --> 00:08:30,737 miles south of San Francisco. 225 00:08:33,071 --> 00:08:34,704 >> We're here at Mussel Rock 226 00:08:34,739 --> 00:08:36,638 and we're essentially standing 227 00:08:36,705 --> 00:08:38,205 on the San Andreas Fault right 228 00:08:38,273 --> 00:08:40,473 now. And if there was an 229 00:08:40,540 --> 00:08:41,473 earthquake, I don't know what 230 00:08:41,540 --> 00:08:43,007 would happen right here, but I 231 00:08:43,074 --> 00:08:45,007 wouldn't want to be here. 232 00:08:47,275 --> 00:08:48,974 >> This Pacific coastline, 233 00:08:49,009 --> 00:08:50,475 where cliffs crumble slowly 234 00:08:50,542 --> 00:08:52,375 into the sea, is the boundary 235 00:08:52,442 --> 00:08:54,109 between two of the Earth's 236 00:08:54,176 --> 00:08:56,110 massive continental plates. 237 00:08:59,011 --> 00:09:00,644 Separated by the San Andreas 238 00:09:00,711 --> 00:09:02,811 Fault, two vast, separate 239 00:09:02,911 --> 00:09:04,443 blocks of the Earth's crust 240 00:09:04,479 --> 00:09:06,112 lie directly alongside each 241 00:09:06,178 --> 00:09:07,712 other. 242 00:09:10,014 --> 00:09:11,179 Here, the continent of North 243 00:09:11,247 --> 00:09:13,246 America lies slightly on top 244 00:09:13,281 --> 00:09:14,648 of the adjacent section of 245 00:09:14,715 --> 00:09:16,282 crust which holds the Pacific 246 00:09:16,348 --> 00:09:18,347 Ocean. 247 00:09:23,549 --> 00:09:25,283 The join can be seen where 248 00:09:25,350 --> 00:09:27,083 these lower, darker rocks are 249 00:09:27,184 --> 00:09:28,717 overlaid by light-colored 250 00:09:28,818 --> 00:09:31,250 sedimentary rocks. 251 00:09:31,286 --> 00:09:32,351 >> These rock types differ 252 00:09:32,452 --> 00:09:34,085 by--by, uh, more than 100 253 00:09:34,186 --> 00:09:35,986 million years in age. Two rock 254 00:09:36,087 --> 00:09:37,686 bodies that, uh, are 255 00:09:37,720 --> 00:09:39,052 not similar in any way have 256 00:09:39,086 --> 00:09:41,886 been brought together. 257 00:09:41,920 --> 00:09:43,353 >> The fault line was exposed 258 00:09:43,454 --> 00:09:45,054 to geologists when the cliffs 259 00:09:45,088 --> 00:09:46,888 collapsed here in the 1906 260 00:09:46,989 --> 00:09:50,621 Earthquake. But, back then, 261 00:09:50,722 --> 00:09:53,356 nobody understood how and why 262 00:09:53,423 --> 00:09:54,623 the two different types of 263 00:09:54,724 --> 00:09:58,089 rock were next to each other, 264 00:09:58,158 --> 00:10:00,591 until around 40 years ago, 265 00:10:00,625 --> 00:10:02,358 when the answer was finally 266 00:10:02,426 --> 00:10:04,592 revealed by the theory of 267 00:10:04,626 --> 00:10:06,725 Plate Tectonics. 268 00:10:09,994 --> 00:10:11,160 The theory showed that the 269 00:10:11,227 --> 00:10:12,861 Earth's crust consists of 270 00:10:12,895 --> 00:10:14,428 separate, moving plates on 271 00:10:14,462 --> 00:10:15,628 which the oceans and 272 00:10:15,696 --> 00:10:17,594 Continents sit. 273 00:10:19,163 --> 00:10:21,162 Around 200 million years ago, 274 00:10:21,230 --> 00:10:22,697 the heavy Pacific Ocean plate 275 00:10:22,730 --> 00:10:24,596 collided with North America, 276 00:10:24,630 --> 00:10:26,430 and started sinking underneath 277 00:10:26,498 --> 00:10:28,631 the lighter Continent. 278 00:10:30,965 --> 00:10:32,598 Professor of Geophysics, Mark 279 00:10:32,632 --> 00:10:34,499 Zoback, studies that process, 280 00:10:34,533 --> 00:10:36,133 called subduction, in his 281 00:10:36,167 --> 00:10:37,332 laboratory at Stanford 282 00:10:37,433 --> 00:10:39,533 University. 283 00:10:39,601 --> 00:10:40,900 >> For many millions of years 284 00:10:40,968 --> 00:10:42,434 prior to the existence of the 285 00:10:42,502 --> 00:10:44,267 San Andreas Fault, the Pacific 286 00:10:44,335 --> 00:10:46,435 Plate was subducting beneath 287 00:10:46,503 --> 00:10:48,135 North America, the Oceanic 288 00:10:48,169 --> 00:10:51,169 Plate was diving down, and, 289 00:10:51,237 --> 00:10:53,704 uh, that process went on for 290 00:10:53,772 --> 00:10:55,671 well over a hundred million 291 00:10:55,705 --> 00:10:57,604 years, so a tremendous amount 292 00:10:57,705 --> 00:11:00,305 of activity was occurring. 293 00:11:00,406 --> 00:11:01,872 >> As the unstoppable force of 294 00:11:01,939 --> 00:11:03,507 one plate met the immovable 295 00:11:03,574 --> 00:11:05,307 object of the other, they were 296 00:11:05,407 --> 00:11:08,273 forced to change direction. 297 00:11:08,308 --> 00:11:10,274 >> About 20 million years ago, 298 00:11:10,309 --> 00:11:12,741 the plate motions were such 299 00:11:12,776 --> 00:11:14,409 that the Pacific Plate had to 300 00:11:14,476 --> 00:11:16,575 start sliding north with 301 00:11:16,677 --> 00:11:18,175 respect to North America, 302 00:11:18,209 --> 00:11:20,276 and now, you know, the--the 303 00:11:20,310 --> 00:11:22,311 principal motion is this 304 00:11:22,412 --> 00:11:24,110 sliding process between the 305 00:11:24,178 --> 00:11:25,677 two plates. And 20 million 306 00:11:25,745 --> 00:11:26,744 years ago, the San Andreas 307 00:11:26,845 --> 00:11:28,545 Fault was born. 308 00:11:28,579 --> 00:11:29,945 >> It was the moving plates 309 00:11:30,047 --> 00:11:31,378 that crushed different types 310 00:11:31,446 --> 00:11:33,645 of rock together, just as here 311 00:11:33,680 --> 00:11:35,213 at Mussel Rock. 312 00:11:37,481 --> 00:11:39,380 At last, the investigation 313 00:11:39,448 --> 00:11:41,681 knows what it is dealing with. 314 00:11:44,082 --> 00:11:46,382 The San Andreas Fault is 800 315 00:11:46,483 --> 00:11:48,582 miles long, emerging from the 316 00:11:48,650 --> 00:11:50,317 seabed north of Point Arena 317 00:11:50,384 --> 00:11:52,016 in Northern California and 318 00:11:52,117 --> 00:11:53,950 running down to the Salton Sea 319 00:11:54,018 --> 00:11:55,584 in the south. 320 00:11:57,585 --> 00:11:58,751 The evidence is coming 321 00:11:58,853 --> 00:12:01,919 together. Clues from the 1906 322 00:12:01,987 --> 00:12:03,354 Earthquake, such as the picket 323 00:12:03,388 --> 00:12:05,086 fence that was torn apart, 324 00:12:05,121 --> 00:12:07,120 prove that the land was 325 00:12:07,188 --> 00:12:10,288 moving. Connecting the dots 326 00:12:10,356 --> 00:12:12,255 identifies the straight line 327 00:12:12,289 --> 00:12:14,289 of the San Andreas Fault. 328 00:12:16,924 --> 00:12:18,856 And Mussel Rock uncovers 329 00:12:18,924 --> 00:12:19,890 different plates of the 330 00:12:19,924 --> 00:12:21,824 Earth's crust on either side 331 00:12:21,924 --> 00:12:23,657 of the fault line. 332 00:12:25,292 --> 00:12:27,358 But investigators still need 333 00:12:27,392 --> 00:12:28,992 more information about how 334 00:12:29,026 --> 00:12:30,527 often the San Andreas has 335 00:12:30,560 --> 00:12:31,892 spawned Earthquakes in the 336 00:12:31,927 --> 00:12:35,193 past. 337 00:12:35,261 --> 00:12:36,661 It might help them answer the 338 00:12:36,729 --> 00:12:39,294 all-important question--when 339 00:12:39,395 --> 00:12:41,262 will the San Andreas strike 340 00:12:41,296 --> 00:12:43,195 again? 341 00:12:48,832 --> 00:12:50,066 To discover when the San 342 00:12:50,100 --> 00:12:51,364 Andreas Fault will strike 343 00:12:51,432 --> 00:12:53,533 again the investigation needs 344 00:12:53,600 --> 00:12:54,899 to know about ancient 345 00:12:54,967 --> 00:12:56,234 earthquakes that have struck 346 00:12:56,268 --> 00:12:58,067 along the fault line. 347 00:13:01,536 --> 00:13:02,901 But there's an immediate 348 00:13:02,969 --> 00:13:04,534 problem. 349 00:13:04,602 --> 00:13:05,602 >> Here in California, it's a 350 00:13:05,702 --> 00:13:06,902 particular challenge, and 351 00:13:06,970 --> 00:13:07,903 some of the earliest written 352 00:13:07,970 --> 00:13:09,236 records were from the missions 353 00:13:09,303 --> 00:13:10,771 and from the early explorers, 354 00:13:10,805 --> 00:13:12,069 So only dating back into the 355 00:13:12,137 --> 00:13:14,071 18th century here. Other 356 00:13:14,172 --> 00:13:15,238 parts of the world, we have an 357 00:13:15,305 --> 00:13:16,404 earthquake history going back 358 00:13:16,439 --> 00:13:18,438 millennia. 359 00:13:18,506 --> 00:13:20,705 >> The investigation moves 350 360 00:13:20,806 --> 00:13:22,672 miles south of San Francisco 361 00:13:22,707 --> 00:13:24,240 to a desert where the San 362 00:13:24,307 --> 00:13:25,774 Andreas may have been active 363 00:13:25,807 --> 00:13:28,074 for thousands of years. 364 00:13:31,509 --> 00:13:33,208 There's crucial evidence here 365 00:13:33,243 --> 00:13:34,709 about earthquakes from ancient 366 00:13:34,777 --> 00:13:37,710 times. 367 00:13:37,778 --> 00:13:38,976 >> This creek used to flow 368 00:13:39,043 --> 00:13:40,144 straight across the San 369 00:13:40,210 --> 00:13:41,576 Andreas Fault here, but 370 00:13:41,611 --> 00:13:43,210 several earthquakes formed a 371 00:13:43,245 --> 00:13:44,577 natural dam where the San 372 00:13:44,612 --> 00:13:46,245 Andreas Fault wedges up here 373 00:13:46,312 --> 00:13:48,411 in front of me. That created a 374 00:13:48,479 --> 00:13:50,346 small pond, and now we're 375 00:13:50,413 --> 00:13:51,579 looking at the dry sediments 376 00:13:51,614 --> 00:13:54,213 of that pond that record the 377 00:13:54,248 --> 00:13:55,413 history of earthquakes, and 378 00:13:55,515 --> 00:13:56,714 that tells us quite a great 379 00:13:56,815 --> 00:13:58,180 deal about the past behavior of 380 00:13:58,248 --> 00:14:01,148 the San Andreas Fault. 381 00:14:01,182 --> 00:14:02,549 >> Some of the clues are so 382 00:14:02,617 --> 00:14:04,283 small that Hudnut's detective 383 00:14:04,351 --> 00:14:06,083 work gets him down and dusty 384 00:14:06,183 --> 00:14:08,150 among tiny cracks inside the 385 00:14:08,184 --> 00:14:09,884 fault. 386 00:14:09,918 --> 00:14:11,252 >> Sometimes we can find out 387 00:14:11,285 --> 00:14:12,683 about the past behavior of 388 00:14:12,718 --> 00:14:13,717 the San Andreas Fault by 389 00:14:13,785 --> 00:14:14,785 looking at the tiniest 390 00:14:14,819 --> 00:14:16,919 details. 391 00:14:16,987 --> 00:14:18,552 >> At the bottom of this small 392 00:14:18,620 --> 00:14:20,952 ancient pond, mud sediments 393 00:14:20,987 --> 00:14:22,553 collected above a fine line of 394 00:14:22,621 --> 00:14:25,720 pebbles. Then an earthquake 395 00:14:25,788 --> 00:14:27,554 shifted the land upwards on 396 00:14:27,622 --> 00:14:29,155 one side of the vertical fault 397 00:14:29,189 --> 00:14:31,322 line. 398 00:14:31,357 --> 00:14:32,789 >> So this layer was 399 00:14:32,823 --> 00:14:34,623 originally flat, and then, in 400 00:14:34,690 --> 00:14:36,156 a subsequent Earthquake, it 401 00:14:36,258 --> 00:14:37,823 was broken like this along 402 00:14:37,891 --> 00:14:39,689 this tiny fracture strand of 403 00:14:39,724 --> 00:14:41,323 the San Andreas Fault. 404 00:14:41,358 --> 00:14:42,991 >> But finding proof that this 405 00:14:43,058 --> 00:14:44,325 is the site of an ancient 406 00:14:44,360 --> 00:14:45,957 earthquake is only part of the 407 00:14:45,992 --> 00:14:48,793 story. Hudnut needs to know 408 00:14:48,860 --> 00:14:51,692 how long ago it happened. 409 00:14:51,727 --> 00:14:52,993 The bare rock layers are no 410 00:14:53,060 --> 00:14:55,361 help in dating his find, but 411 00:14:55,428 --> 00:14:56,694 just above the fracture line 412 00:14:56,729 --> 00:14:58,527 of the rocks he has found the 413 00:14:58,629 --> 00:15:01,529 evidence he needs. 414 00:15:01,596 --> 00:15:03,363 >> Here, a bush was burned by 415 00:15:03,430 --> 00:15:05,529 a prehistoric wildfire, and 416 00:15:05,596 --> 00:15:07,163 that remnant of carbon is why 417 00:15:07,264 --> 00:15:08,697 you see this black stain on 418 00:15:08,799 --> 00:15:11,231 the side of the trench wall. 419 00:15:11,266 --> 00:15:12,697 >> The key to unlocking the 420 00:15:12,765 --> 00:15:15,431 age of the rocks is carbon-14, 421 00:15:15,533 --> 00:15:18,333 known as radiocarbon. 422 00:15:18,401 --> 00:15:19,699 Its molecular structure 423 00:15:19,800 --> 00:15:21,599 means that carbon-14 is a 424 00:15:21,700 --> 00:15:23,433 more unstable isotope than 425 00:15:23,535 --> 00:15:25,401 other forms of carbon. 426 00:15:25,435 --> 00:15:26,801 It's absorbed by growing 427 00:15:26,902 --> 00:15:28,501 plants, then radioactively 428 00:15:28,536 --> 00:15:30,402 decays at a known rate, after 429 00:15:30,436 --> 00:15:32,803 the plant dies. So measuring 430 00:15:32,870 --> 00:15:34,969 carbon-14 in vegetation burned 431 00:15:35,037 --> 00:15:37,404 in a wildfire reveals how long 432 00:15:37,438 --> 00:15:39,603 ago those plants died, and 433 00:15:39,704 --> 00:15:41,237 dates the rock in which the 434 00:15:41,338 --> 00:15:43,772 carbon is found. 435 00:15:43,807 --> 00:15:45,039 >> And through this, we can 436 00:15:45,073 --> 00:15:46,972 reconstruct the evidence of 437 00:15:47,040 --> 00:15:48,973 the past earthquakes. 438 00:15:49,041 --> 00:15:50,574 >> Radiocarbon dating has 439 00:15:50,608 --> 00:15:52,240 proved that earthquakes have 440 00:15:52,308 --> 00:15:53,607 been happening along the line 441 00:15:53,708 --> 00:15:55,408 of the San Andreas for 442 00:15:55,442 --> 00:15:57,975 thousands of years. The 443 00:15:58,043 --> 00:15:59,575 particular small earthquake 444 00:15:59,609 --> 00:16:01,242 investigated by Hudnut, for 445 00:16:01,343 --> 00:16:04,343 example, is around 3,500 years 446 00:16:04,411 --> 00:16:06,977 old. It happened at a time 447 00:16:07,044 --> 00:16:08,711 when the last Woolly Mammoths 448 00:16:08,778 --> 00:16:11,512 were dying out in North America. 449 00:16:14,980 --> 00:16:16,513 The investigation moves to an 450 00:16:16,581 --> 00:16:18,979 even more remote desert spot. 451 00:16:19,047 --> 00:16:21,580 The Carrizo Plain, 160 miles 452 00:16:21,614 --> 00:16:23,582 north of Los Angeles. Here 453 00:16:23,616 --> 00:16:25,415 lies a dried-up riverbed, 454 00:16:25,516 --> 00:16:26,981 which takes an unusual 455 00:16:27,049 --> 00:16:30,615 course. Coming down off the 456 00:16:30,684 --> 00:16:32,249 hills, the creek bed takes a 457 00:16:32,316 --> 00:16:34,116 sudden, sharp turn to its 458 00:16:34,150 --> 00:16:37,684 right. A few hundred feet 459 00:16:37,785 --> 00:16:39,317 later, it makes an equally 460 00:16:39,385 --> 00:16:41,385 odd, 90-degree turn to the 461 00:16:41,420 --> 00:16:42,885 left. 462 00:16:45,686 --> 00:16:47,386 The creek crossed the line of 463 00:16:47,420 --> 00:16:49,588 the San Andreas Fault, but 464 00:16:49,655 --> 00:16:50,954 early geologists were 465 00:16:51,055 --> 00:16:54,688 mystified. Why did it bend in 466 00:16:54,756 --> 00:16:56,155 this way? 467 00:16:59,223 --> 00:17:00,789 The scientific pioneers were 468 00:17:00,857 --> 00:17:02,490 limited to studies on the 469 00:17:02,591 --> 00:17:05,291 ground. Nowadays, Hudnut has an 470 00:17:05,325 --> 00:17:07,558 advantage. He can take to the 471 00:17:07,592 --> 00:17:09,058 air. 472 00:17:14,060 --> 00:17:15,226 >> the San Andreas Fault, 473 00:17:15,327 --> 00:17:16,394 Where it cuts though the 474 00:17:16,495 --> 00:17:17,694 Carrizo plain, it almost looks 475 00:17:17,762 --> 00:17:19,760 Like a scar, and it was caused 476 00:17:19,828 --> 00:17:21,228 by repeated earthquakes in the 477 00:17:21,328 --> 00:17:22,395 past. 478 00:17:22,461 --> 00:17:23,829 >> Along the long line of 479 00:17:23,863 --> 00:17:25,129 hills marking the course of 480 00:17:25,197 --> 00:17:27,496 the San Andreas, Hudnut spots 481 00:17:27,564 --> 00:17:28,963 the puzzling bends that he's 482 00:17:29,031 --> 00:17:30,764 seeking. 483 00:17:32,098 --> 00:17:33,397 >> Hudnut: Oh! If we could 484 00:17:33,498 --> 00:17:34,764 woop along the fault through 485 00:17:34,832 --> 00:17:35,864 here, that would be awesome. 486 00:17:35,932 --> 00:17:37,766 Oh, there's a great angle, see 487 00:17:37,867 --> 00:17:39,666 that right angle, uh, offset 488 00:17:39,732 --> 00:17:40,965 channel with the elbow in it 489 00:17:41,033 --> 00:17:42,766 right there? That's a classic 490 00:17:42,867 --> 00:17:45,868 one right there. 491 00:17:45,936 --> 00:17:47,233 >> Hudnut's aerial view of 492 00:17:47,301 --> 00:17:48,768 the creek bed shows that the 493 00:17:48,836 --> 00:17:50,768 river once flowed straight on 494 00:17:50,869 --> 00:17:54,468 cross the fault. But, little 495 00:17:54,503 --> 00:17:56,236 By little, a series of 496 00:17:56,304 --> 00:17:57,504 Earthquakes along the San 497 00:17:57,571 --> 00:17:59,770 Andreas dragged the creek away 498 00:17:59,870 --> 00:18:01,636 from its original course. 499 00:18:03,872 --> 00:18:05,672 Recreating how the land had 500 00:18:05,739 --> 00:18:07,405 moved showed Hudnut that the 501 00:18:07,506 --> 00:18:09,038 two parts of the creek had 502 00:18:09,140 --> 00:18:11,406 traveled more than 300 feet 503 00:18:11,473 --> 00:18:12,906 apart. 504 00:18:14,307 --> 00:18:15,407 >> So if you imagine the North 505 00:18:15,474 --> 00:18:17,041 American plate is fixed and 506 00:18:17,108 --> 00:18:19,108 the Pacific Plate is moving to 507 00:18:19,210 --> 00:18:21,208 the northwest, the Wallace 508 00:18:21,309 --> 00:18:23,209 Creek site records that offset 509 00:18:23,276 --> 00:18:24,476 because the channel is 510 00:18:24,577 --> 00:18:25,776 straight across the fault, 511 00:18:25,844 --> 00:18:27,109 but it's been offset through 512 00:18:27,177 --> 00:18:28,844 time. 513 00:18:28,945 --> 00:18:30,311 >> Earlier investigators had 514 00:18:30,377 --> 00:18:32,211 already radiocarbon-dated the 515 00:18:32,278 --> 00:18:34,111 land on each side of the fault 516 00:18:34,213 --> 00:18:35,946 here, revealing that it took 517 00:18:36,013 --> 00:18:38,478 3,000 years to change the 518 00:18:38,581 --> 00:18:40,112 creek's position. 519 00:18:41,747 --> 00:18:43,580 So, knowing the distance and 520 00:18:43,647 --> 00:18:45,480 the time it took to do it lets 521 00:18:45,548 --> 00:18:47,380 Hudnut calculate the average 522 00:18:47,481 --> 00:18:49,215 speed with which the two land 523 00:18:49,282 --> 00:18:50,949 masses are moving past each 524 00:18:51,016 --> 00:18:52,449 other. 525 00:18:53,716 --> 00:18:58,917 300 feet in 3,000 years, 526 00:18:58,952 --> 00:19:01,852 one foot per decade, 527 00:19:01,919 --> 00:19:05,219 just over an inch a year. 528 00:19:05,286 --> 00:19:06,918 But this was never a steady, 529 00:19:06,986 --> 00:19:08,385 sliding, one-inch-a-year 530 00:19:08,453 --> 00:19:10,719 movement. The reality was a 531 00:19:10,754 --> 00:19:13,553 series of sudden small jumps 532 00:19:13,621 --> 00:19:14,753 whenever tension built up 533 00:19:14,821 --> 00:19:16,054 enough between the two 534 00:19:16,088 --> 00:19:17,888 moving plates to overcome 535 00:19:17,990 --> 00:19:20,622 friction between the rocks and 536 00:19:20,690 --> 00:19:21,989 rip the land apart with an 537 00:19:22,057 --> 00:19:23,889 earthquake. 538 00:19:25,425 --> 00:19:26,690 It's an important moment for 539 00:19:26,724 --> 00:19:30,091 the investigation. Knowing how 540 00:19:30,159 --> 00:19:32,158 fast the land is moving not 541 00:19:32,227 --> 00:19:34,358 only reveals the stress that's 542 00:19:34,426 --> 00:19:37,159 building up, but also the risk 543 00:19:37,260 --> 00:19:39,427 of an earthquake. 544 00:19:43,863 --> 00:19:45,428 The San Andreas Fault is 545 00:19:45,495 --> 00:19:48,329 giving up its secrets. Clues 546 00:19:48,363 --> 00:19:49,995 from a long dried-up pond 547 00:19:50,063 --> 00:19:51,696 reveal the site of ancient 548 00:19:51,797 --> 00:19:54,864 earthquakes. Carbon from a 549 00:19:54,898 --> 00:19:56,598 prehistoric fire provides the 550 00:19:56,698 --> 00:19:59,966 dates. And bends in a riverbed 551 00:20:00,033 --> 00:20:02,065 prove how fast the plates are 552 00:20:02,132 --> 00:20:05,433 moving along the San Andreas. 553 00:20:05,534 --> 00:20:07,132 But now, the investigation has 554 00:20:07,167 --> 00:20:11,234 a new mystery to solve. If the 555 00:20:11,335 --> 00:20:13,401 land along the San Andreas is 556 00:20:13,436 --> 00:20:15,401 moving one inch every year, 557 00:20:15,436 --> 00:20:17,970 causing earthquakes, then why 558 00:20:18,036 --> 00:20:20,136 has one small town along the 559 00:20:20,171 --> 00:20:22,970 fault line never had any? 560 00:20:30,036 --> 00:20:31,202 The investigation has 561 00:20:31,236 --> 00:20:32,968 discovered how fast the land 562 00:20:33,037 --> 00:20:34,335 is stretching and straining 563 00:20:34,403 --> 00:20:36,036 along each side of the San 564 00:20:36,104 --> 00:20:38,404 Andreas Fault, which should 565 00:20:38,472 --> 00:20:40,372 help establish when that 566 00:20:40,405 --> 00:20:41,837 ever-increasing stress will 567 00:20:41,871 --> 00:20:43,238 snap the land apart in the 568 00:20:43,306 --> 00:20:45,372 next major earthquake. 569 00:20:46,406 --> 00:20:48,672 But there's a problem. One 570 00:20:48,773 --> 00:20:50,207 oart of the fault line just 571 00:20:50,240 --> 00:20:53,940 doesn't fit the pattern. 572 00:20:54,008 --> 00:20:55,741 The small town of Hollister is 573 00:20:55,775 --> 00:20:57,308 unique along the San Andreas 574 00:20:57,409 --> 00:20:59,475 Fault system. It's never had 575 00:20:59,509 --> 00:21:01,142 an earthquake. And the 576 00:21:01,209 --> 00:21:02,942 investigation is going to find 577 00:21:03,010 --> 00:21:05,010 out why. 578 00:21:09,678 --> 00:21:11,678 Hollister has a population of 579 00:21:11,779 --> 00:21:17,312 37,000, and nothing here is 580 00:21:17,413 --> 00:21:19,113 quite the way it should be. 581 00:21:23,047 --> 00:21:24,648 There are plenty of clues 582 00:21:24,682 --> 00:21:26,415 suggesting that the land must 583 00:21:26,483 --> 00:21:28,414 be moving here. 584 00:21:32,850 --> 00:21:36,117 Sidewalks with cracks in, 585 00:21:36,218 --> 00:21:39,118 curbstones way out of line and 586 00:21:39,219 --> 00:21:41,285 walls that are bent out of 587 00:21:41,319 --> 00:21:42,318 shape. 588 00:21:42,386 --> 00:21:44,085 >> Walking through Hollister, 589 00:21:44,120 --> 00:21:45,319 we can see anything that man 590 00:21:45,387 --> 00:21:46,819 has built that was laid out in 591 00:21:46,921 --> 00:21:48,985 a straight line may have a jog 592 00:21:49,054 --> 00:21:51,453 in it. Every year it changes a 593 00:21:51,521 --> 00:21:53,087 little bit, it's a progressive 594 00:21:53,188 --> 00:21:54,820 thing. 595 00:21:54,888 --> 00:21:56,521 >> The clues add up to one 596 00:21:56,555 --> 00:21:59,622 clear conclusion. Even without 597 00:21:59,690 --> 00:22:01,455 any earthquakes, the Earth in 598 00:22:01,523 --> 00:22:02,822 this town in the heart of the 599 00:22:02,890 --> 00:22:04,723 San Andreas system still 600 00:22:04,791 --> 00:22:06,958 slides imperceptibly slowly 601 00:22:06,992 --> 00:22:10,158 and effortlessly along. 602 00:22:10,192 --> 00:22:11,959 >> In one sense, the damage 603 00:22:11,992 --> 00:22:13,326 that you see here associated 604 00:22:13,360 --> 00:22:14,625 with the creeping is, uh, is 605 00:22:14,726 --> 00:22:16,159 clearly sort of under control. 606 00:22:16,260 --> 00:22:18,359 But as a geologist, if you start 607 00:22:18,460 --> 00:22:20,260 playing that out for tens of 608 00:22:20,362 --> 00:22:21,427 thousands or hundreds of 609 00:22:21,461 --> 00:22:22,627 thousands or millions of 610 00:22:22,695 --> 00:22:24,295 years, the consequences of 611 00:22:24,362 --> 00:22:26,095 that become enormous. 612 00:22:26,163 --> 00:22:27,429 >> For many years, the 613 00:22:27,463 --> 00:22:28,862 creeping ground that moved 614 00:22:28,896 --> 00:22:30,529 without earthquakes remained 615 00:22:30,630 --> 00:22:32,530 an unsolved mystery. 616 00:22:35,898 --> 00:22:38,232 But then, the investigation 617 00:22:38,266 --> 00:22:40,432 moved 100 miles south, to 618 00:22:40,500 --> 00:22:42,165 another small community, where 619 00:22:42,233 --> 00:22:45,133 the land also creeps along. 620 00:22:48,334 --> 00:22:49,700 The village of Parkfield has a 621 00:22:49,768 --> 00:22:52,434 population of just 37 people, 622 00:22:52,502 --> 00:22:54,436 and a bridge which spans right 623 00:22:54,504 --> 00:22:58,536 across the San Andreas Fault. 624 00:22:58,604 --> 00:22:59,704 The bridge separates the 625 00:22:59,771 --> 00:23:02,670 Pacific Plate on one side from 626 00:23:02,704 --> 00:23:04,137 the North American Plate on 627 00:23:04,172 --> 00:23:06,872 the other. And the bridge 628 00:23:06,906 --> 00:23:10,171 railings have started to bend. 629 00:23:10,239 --> 00:23:11,806 >> I'm, uh, right now on the 630 00:23:11,873 --> 00:23:15,073 Pacific Plate on the west side 631 00:23:15,141 --> 00:23:18,240 of the San Andreas Fault, and 632 00:23:18,308 --> 00:23:20,342 you know, the--the San Andreas 633 00:23:20,443 --> 00:23:21,707 comes off the flank of that 634 00:23:21,808 --> 00:23:23,876 hill and right across that 635 00:23:23,943 --> 00:23:25,976 field, right under the bridge, 636 00:23:26,044 --> 00:23:27,576 and then, right over by the 637 00:23:27,611 --> 00:23:28,575 corner of that building or 638 00:23:28,610 --> 00:23:30,144 that fence post and then on 639 00:23:30,245 --> 00:23:33,344 off to Middle Mountain. 640 00:23:33,445 --> 00:23:34,511 >> The movement here around 641 00:23:34,613 --> 00:23:35,978 the bridge is strikingly 642 00:23:36,078 --> 00:23:37,712 similar to the slow creeping 643 00:23:37,779 --> 00:23:41,313 ground of Hollister. 644 00:23:41,347 --> 00:23:42,512 But there is one important 645 00:23:42,614 --> 00:23:44,514 difference here in Parkfield. 646 00:23:44,615 --> 00:23:46,348 Every couple of decades or so, 647 00:23:46,415 --> 00:23:47,982 this village does have 648 00:23:48,050 --> 00:23:50,514 earthquakes. They're just 649 00:23:50,615 --> 00:23:52,348 little tremors, but they're 650 00:23:52,416 --> 00:23:53,982 big enough to be recorded on 651 00:23:54,050 --> 00:23:55,149 earthquake monitoring 652 00:23:55,250 --> 00:23:57,050 seismographs. 653 00:24:00,585 --> 00:24:02,150 That's why the village proudly 654 00:24:02,251 --> 00:24:04,152 boasts of being the earthquake 655 00:24:04,219 --> 00:24:07,319 capital of the world. But it's 656 00:24:07,386 --> 00:24:08,985 perhaps more accurately called 657 00:24:09,053 --> 00:24:10,819 the earthquake study capital 658 00:24:10,853 --> 00:24:12,120 because scientists are 659 00:24:12,221 --> 00:24:13,486 fascinated by the fact that 660 00:24:13,554 --> 00:24:14,921 earthquakes here follow a 661 00:24:14,989 --> 00:24:16,654 predictable pattern. 662 00:24:19,221 --> 00:24:21,089 Elsewhere, earthquakes always 663 00:24:21,123 --> 00:24:23,089 strike without warning, the 664 00:24:23,123 --> 00:24:24,656 toll of death and destruction 665 00:24:24,724 --> 00:24:26,557 made worse because nobody knew 666 00:24:26,658 --> 00:24:29,656 they were coming. So 667 00:24:29,724 --> 00:24:31,091 scientists are desperate for 668 00:24:31,125 --> 00:24:32,758 any clues that might help 669 00:24:32,826 --> 00:24:34,391 predict when an earthquake 670 00:24:34,459 --> 00:24:37,124 could happen. And here in 671 00:24:37,193 --> 00:24:38,759 Parkfield, the earthquakes 672 00:24:38,826 --> 00:24:40,193 happen with astonishing 673 00:24:40,261 --> 00:24:42,392 regularity, on average, every 674 00:24:42,460 --> 00:24:46,162 couple of decades or so. Minor 675 00:24:46,196 --> 00:24:48,727 quakes happened here in 1857, 676 00:24:48,829 --> 00:24:55,029 1881, 1901, 1922, 1934 and 677 00:24:55,098 --> 00:24:56,830 1966. 678 00:24:58,931 --> 00:25:00,931 After the '66 Earthquake, 679 00:25:00,999 --> 00:25:02,664 investigators set up a network 680 00:25:02,732 --> 00:25:04,265 of monitoring instruments to 681 00:25:04,299 --> 00:25:05,833 see if the fault gave any 682 00:25:05,900 --> 00:25:08,000 warning before the next 683 00:25:08,068 --> 00:25:10,633 earthquake arrived. 684 00:25:10,667 --> 00:25:11,933 They expected it sometime 685 00:25:12,001 --> 00:25:15,201 between 1988 and 1993, but it 686 00:25:15,269 --> 00:25:17,168 was late. And months of 687 00:25:17,202 --> 00:25:20,536 waiting stretched into years. 688 00:25:24,071 --> 00:25:25,837 But still the scientists 689 00:25:25,905 --> 00:25:28,538 waited, until finally, in 690 00:25:28,639 --> 00:25:30,571 December 2004, the 691 00:25:30,638 --> 00:25:32,072 long-awaited earthquake 692 00:25:32,106 --> 00:25:34,540 arrived and was caught on 693 00:25:34,607 --> 00:25:37,539 film, from a now slightly worn 694 00:25:37,640 --> 00:25:39,606 and damaged camera. 695 00:25:45,543 --> 00:25:47,176 The Earthquake movie may not 696 00:25:47,277 --> 00:25:49,175 have seemed that impressive, 697 00:25:49,276 --> 00:25:50,543 but the instruments collected 698 00:25:50,610 --> 00:25:52,876 a mass of information. 699 00:25:55,445 --> 00:25:57,077 The data didn't, after all, 700 00:25:57,111 --> 00:25:58,078 help with earthquake 701 00:25:58,179 --> 00:25:59,912 prediction, but it did 702 00:25:59,979 --> 00:26:01,712 pinpoint where the earthquake 703 00:26:01,746 --> 00:26:03,913 started underground, which 704 00:26:03,980 --> 00:26:05,879 told investigators where to 705 00:26:05,914 --> 00:26:10,780 look next, deep down under the 706 00:26:10,815 --> 00:26:14,182 Parkfield countryside. 707 00:26:14,283 --> 00:26:16,181 Starting slightly to one side 708 00:26:16,282 --> 00:26:18,350 of the fault, the aim was to 709 00:26:18,383 --> 00:26:20,350 angle in and stab into the 710 00:26:20,417 --> 00:26:24,350 very heart of the San Andreas. 711 00:26:24,451 --> 00:26:25,917 After three years of drilling, 712 00:26:25,985 --> 00:26:27,718 long cores of rock were 713 00:26:27,819 --> 00:26:29,784 extracted from the exact spot 714 00:26:29,819 --> 00:26:31,787 where the Earthquake occurred. 715 00:26:33,087 --> 00:26:35,386 This was first time the team leader 716 00:26:35,387 --> 00:26:37,185 geologist Mark Zoback had ever 717 00:26:37,186 --> 00:26:38,684 seen rocks from the center 718 00:26:38,685 --> 00:26:39,685 of the San Andreas. 719 00:26:42,184 --> 00:26:43,283 What we're looking at here 720 00:26:43,284 --> 00:26:44,383 are cores from the 721 00:26:44,384 --> 00:26:45,883 active San Andreas Fault, 722 00:26:45,884 --> 00:26:47,583 from a depth of about 2 miles. 723 00:26:47,984 --> 00:26:50,181 So for the Earth science community 724 00:26:50,182 --> 00:26:52,182 these are like Moon rocks. 725 00:26:52,183 --> 00:26:53,382 As we were trying to exhume 726 00:26:53,383 --> 00:26:54,681 these cores, we had a great 727 00:26:54,682 --> 00:26:57,480 deal of drilling difficulty. 728 00:26:57,481 --> 00:26:58,880 The San Andreas Fault was 729 00:26:58,881 --> 00:27:00,381 literally fighting back. 730 00:27:00,681 --> 00:27:02,778 After 9 weeks of attempting 731 00:27:02,779 --> 00:27:04,578 to recover the cores in the middle 732 00:27:04,679 --> 00:27:06,378 of a huge lightening storm 733 00:27:06,379 --> 00:27:07,978 almost a scene directly 734 00:27:07,979 --> 00:27:08,979 out of Hollywood, 735 00:27:08,979 --> 00:27:10,577 with the thunder and lightening, 736 00:27:10,179 --> 00:27:13,276 these cores came to the surface. 737 00:27:14,376 --> 00:27:15,476 And so it was a tremendous 738 00:27:15,477 --> 00:27:16,875 feeling of satisfaction. 739 00:27:17,775 --> 00:27:19,275 The lightening and thunder 740 00:27:19,276 --> 00:27:20,275 just made it that much more 741 00:27:20,276 --> 00:27:21,275 dramatic. 742 00:27:21,476 --> 00:27:22,974 And we're all wearing gloves 743 00:27:24,174 --> 00:27:25,074 we didn't want any oil 744 00:27:25,075 --> 00:27:26,874 from our fingers to affect the core. 745 00:27:27,175 --> 00:27:29,273 And the rule was 746 00:27:29,274 --> 00:27:30,572 that you touched the core 747 00:27:30,573 --> 00:27:31,573 as little as possible. 748 00:27:32,673 --> 00:27:33,573 Obviously. 749 00:27:33,973 --> 00:27:34,873 >> I'm not going to wait for 750 00:27:34,908 --> 00:27:38,473 you guys. Oh, look at this 751 00:27:38,541 --> 00:27:40,008 beautiful rock. 752 00:27:40,075 --> 00:27:41,708 >> The reality was we couldn't 753 00:27:41,743 --> 00:27:43,874 help ourselves, and, uh, um, 754 00:27:43,909 --> 00:27:45,642 it was just such a remarkable 755 00:27:45,743 --> 00:27:46,809 thing to be actually looking 756 00:27:46,877 --> 00:27:48,242 at the San Andreas Fault, uh, 757 00:27:48,277 --> 00:27:49,342 for the very first time 758 00:27:49,444 --> 00:27:50,910 that--that we all got to touch 759 00:27:51,011 --> 00:27:52,544 it a little bit. 760 00:27:52,611 --> 00:27:53,544 >> Buried within the rock 761 00:27:53,611 --> 00:27:55,344 cores, they found a vital 762 00:27:55,379 --> 00:27:57,144 clue about the way that land 763 00:27:57,178 --> 00:28:00,646 slips along the San Andreas. 764 00:28:00,713 --> 00:28:03,812 They found serpentinite. 765 00:28:03,914 --> 00:28:05,914 >> Serpentinite is an unusual 766 00:28:05,981 --> 00:28:07,548 rock type, it was originally 767 00:28:07,649 --> 00:28:09,181 formed, uh, at the base of the 768 00:28:09,283 --> 00:28:10,981 Ocean crust and exhumed up 769 00:28:11,049 --> 00:28:12,514 onto the continent, but the 770 00:28:12,549 --> 00:28:14,616 reason that serpentinite is so 771 00:28:14,683 --> 00:28:15,982 interesting is that 772 00:28:16,050 --> 00:28:18,349 serpentinite is very easily 773 00:28:18,450 --> 00:28:20,449 altered to talc. It allows the 774 00:28:20,551 --> 00:28:22,084 rock to slide at very low 775 00:28:22,151 --> 00:28:24,083 force levels, it's--talcum 776 00:28:24,151 --> 00:28:26,418 powder is very slippery. 777 00:28:26,452 --> 00:28:27,451 >> Talc's crystalline 778 00:28:27,553 --> 00:28:29,185 structure of soft, sliding, 779 00:28:29,253 --> 00:28:31,085 flat plates makes it one of 780 00:28:31,153 --> 00:28:32,786 the slipperiest rocks known to 781 00:28:32,820 --> 00:28:34,353 science. 782 00:28:35,988 --> 00:28:38,721 >> So talc could well be, um, 783 00:28:38,822 --> 00:28:40,821 a key mineral in--in deciding 784 00:28:40,889 --> 00:28:42,622 how the fault is--is actually 785 00:28:42,723 --> 00:28:44,322 working in--in central 786 00:28:44,356 --> 00:28:46,355 California. We see that the 787 00:28:46,456 --> 00:28:48,223 secret of the slipping San 788 00:28:48,257 --> 00:28:49,724 Andreas Fault is actually the 789 00:28:49,791 --> 00:28:50,989 rocks themselves. 790 00:28:51,057 --> 00:28:53,357 >> The talc explains the tiny 791 00:28:53,425 --> 00:28:55,625 earthquakes of Parkfield. 792 00:28:55,693 --> 00:28:56,991 Nobody's yet drilled to 793 00:28:57,059 --> 00:28:58,258 investigate the rocks at 794 00:28:58,327 --> 00:28:59,892 Hollister, but scientists 795 00:28:59,960 --> 00:29:01,726 suspect the talc is present 796 00:29:01,794 --> 00:29:05,694 there too. Cracks in the walls 797 00:29:05,795 --> 00:29:07,361 show the land creeps in 798 00:29:07,429 --> 00:29:10,694 Hollister. And a bend in the 799 00:29:10,796 --> 00:29:12,428 bridge reveals the same 800 00:29:12,496 --> 00:29:13,696 creeping ground in a 801 00:29:13,764 --> 00:29:16,597 nearby town. Rock cores, 802 00:29:16,631 --> 00:29:17,696 extracted from the fault, 803 00:29:17,797 --> 00:29:20,231 contain serpentinite, 804 00:29:20,265 --> 00:29:21,765 leading investigators to the 805 00:29:21,799 --> 00:29:23,264 softest and slipperiest 806 00:29:23,333 --> 00:29:25,265 mineral, talc, which 807 00:29:25,333 --> 00:29:26,966 lubricates some parts of the 808 00:29:27,067 --> 00:29:29,767 Fault. The investigation is 809 00:29:29,801 --> 00:29:31,533 having success, but one 810 00:29:31,601 --> 00:29:33,234 crucial question remains to be 811 00:29:33,268 --> 00:29:35,135 answered. What will the San 812 00:29:35,169 --> 00:29:37,701 Andreas Fault do next? 813 00:29:44,978 --> 00:29:46,377 The investigation into the San 814 00:29:46,444 --> 00:29:48,011 Andreas Fault is trying to 815 00:29:48,078 --> 00:29:49,745 predict when and where its 816 00:29:49,812 --> 00:29:51,278 next major Earthquake will 817 00:29:51,346 --> 00:29:54,713 strike. So far, the only 818 00:29:54,814 --> 00:29:56,380 certain prediction is the far 819 00:29:56,448 --> 00:29:57,912 distant future of the San 820 00:29:57,980 --> 00:29:59,347 Andreas. 821 00:30:01,548 --> 00:30:03,981 Look 20 million years ahead. 822 00:30:04,081 --> 00:30:05,247 If the plate movements 823 00:30:05,281 --> 00:30:06,548 continue to follow their 824 00:30:06,616 --> 00:30:08,416 pattern, Los Angeles will end 825 00:30:08,450 --> 00:30:10,250 up becoming a suburb of San 826 00:30:10,284 --> 00:30:11,816 Francisco. 827 00:30:14,084 --> 00:30:15,284 But predictions on a shorter 828 00:30:15,352 --> 00:30:18,885 timescale are more difficult. 829 00:30:18,919 --> 00:30:20,085 >> If you were to ask the 830 00:30:20,185 --> 00:30:21,985 question, "can we predict 831 00:30:22,086 --> 00:30:23,918 Earthquakes?" my answer would 832 00:30:23,986 --> 00:30:25,986 be, "no, because I know what 833 00:30:26,087 --> 00:30:28,453 your question really meant, 834 00:30:28,521 --> 00:30:30,054 is, you know, 'can we predict 835 00:30:30,088 --> 00:30:31,153 that an Earthquake is going to 836 00:30:31,187 --> 00:30:32,721 occur on a certain fault at a 837 00:30:32,822 --> 00:30:34,355 certain time that we can 838 00:30:34,423 --> 00:30:35,721 specify in the future?'" 839 00:30:35,790 --> 00:30:37,454 And we cannot do that. But 840 00:30:37,522 --> 00:30:39,456 there are many things we can 841 00:30:39,524 --> 00:30:41,089 predict. We can predict which 842 00:30:41,158 --> 00:30:42,224 faults are likely to produce 843 00:30:42,258 --> 00:30:43,624 the big earthquakes, we can 844 00:30:43,692 --> 00:30:44,990 predict how big the 845 00:30:45,091 --> 00:30:46,357 earthquakes are likely to be, 846 00:30:46,425 --> 00:30:47,458 and we can even predict the 847 00:30:47,526 --> 00:30:49,625 probability of the earthquake 848 00:30:49,726 --> 00:30:51,325 occurrence over some period of 849 00:30:51,359 --> 00:30:53,526 several decades. 850 00:30:53,593 --> 00:30:54,793 >> Predictions are most 851 00:30:54,894 --> 00:30:56,660 crucial where the San Andreas 852 00:30:56,695 --> 00:30:58,394 runs to the south of L.A. 853 00:31:00,762 --> 00:31:02,029 Here in the Coachella Valley 854 00:31:02,130 --> 00:31:04,228 Desert, geological evidence of 855 00:31:04,295 --> 00:31:05,496 earthquakes stretches back 856 00:31:05,597 --> 00:31:09,130 1500 years and more. 857 00:31:09,231 --> 00:31:10,765 And they follow a regular 858 00:31:10,831 --> 00:31:12,964 pattern. Major Earthquakes 859 00:31:13,032 --> 00:31:14,564 strike here with monotonous 860 00:31:14,599 --> 00:31:17,730 regularity, every 200 years. 861 00:31:19,366 --> 00:31:21,500 But the latest one is long 862 00:31:21,601 --> 00:31:23,733 overdue. There hasn't been an 863 00:31:23,768 --> 00:31:25,200 earthquake here for more than 864 00:31:25,234 --> 00:31:29,568 300 years. That's a concern, 865 00:31:29,636 --> 00:31:31,000 because parts of the San 866 00:31:31,035 --> 00:31:32,402 Andreas Fault system run 867 00:31:32,503 --> 00:31:34,102 straight from here towards the 868 00:31:34,137 --> 00:31:35,770 city of Los Angeles. 869 00:31:38,137 --> 00:31:39,404 The faults will transmit 870 00:31:39,471 --> 00:31:40,770 earthquake shocks in a 871 00:31:40,837 --> 00:31:41,937 straight line towards 872 00:31:42,039 --> 00:31:44,837 California's biggest city. 873 00:31:44,905 --> 00:31:46,938 Geologist Yuri Fialko 874 00:31:47,040 --> 00:31:48,406 regularly monitors how the 875 00:31:48,473 --> 00:31:50,206 ground moves on either side of 876 00:31:50,274 --> 00:31:51,939 the fault line. 877 00:31:53,908 --> 00:31:55,840 He lines up his gps equipment 878 00:31:55,941 --> 00:31:57,574 precisely over a series of 879 00:31:57,642 --> 00:31:59,108 metal pegs fixed into the 880 00:31:59,208 --> 00:32:01,175 ground. 881 00:32:04,377 --> 00:32:05,842 >> This information is crucial 882 00:32:05,943 --> 00:32:07,743 for estimating how fast the 883 00:32:07,843 --> 00:32:10,045 Fault slips at depth and what 884 00:32:10,112 --> 00:32:11,577 is the rate of accumulation of 885 00:32:11,645 --> 00:32:12,944 strain in the crust. In other 886 00:32:13,011 --> 00:32:15,179 words, how close the crust is 887 00:32:15,213 --> 00:32:18,112 brought to failure by a slip 888 00:32:18,179 --> 00:32:19,646 of the fault at depth. 889 00:32:19,680 --> 00:32:21,212 >> The repeated, ultra-precise 890 00:32:21,314 --> 00:32:22,946 measurements reveal that land 891 00:32:23,014 --> 00:32:25,014 here, on the surface, hardly 892 00:32:25,114 --> 00:32:27,114 moves at all. This is a 893 00:32:27,215 --> 00:32:28,648 problem, because deep 894 00:32:28,716 --> 00:32:30,282 underground, the stresses and 895 00:32:30,383 --> 00:32:32,848 strains are still building up. 896 00:32:32,917 --> 00:32:33,916 >> The fault is moving, at 897 00:32:34,017 --> 00:32:36,083 depth, at a fairly high speed, 898 00:32:36,117 --> 00:32:37,984 and this deformation is 899 00:32:38,018 --> 00:32:38,983 growing and growing and 900 00:32:39,017 --> 00:32:41,018 growing with time. 901 00:32:42,552 --> 00:32:44,385 >> Miles underground, the deep 902 00:32:44,453 --> 00:32:46,118 fault is moving at more than 903 00:32:46,186 --> 00:32:50,387 an inch a year, which tells 904 00:32:50,454 --> 00:32:51,987 Fialko that in the centuries 905 00:32:52,021 --> 00:32:53,920 since the last quake, the 906 00:32:53,988 --> 00:32:55,288 surface should have shifted 907 00:32:55,356 --> 00:32:59,288 300 inches, 25 feet or more. 908 00:33:00,724 --> 00:33:03,189 But it hasn't, so sooner or 909 00:33:03,257 --> 00:33:04,922 later, something's got to 910 00:33:04,990 --> 00:33:08,290 give. And Fialko knows what 911 00:33:08,391 --> 00:33:11,291 that something will be. 912 00:33:11,393 --> 00:33:13,558 The rocks themselves. 913 00:33:15,660 --> 00:33:20,460 >> And one example is this 914 00:33:20,528 --> 00:33:21,927 type of rock, which is called, 915 00:33:22,028 --> 00:33:23,162 uh, granite, and this is in 916 00:33:23,196 --> 00:33:24,728 fact the rock out of which 917 00:33:24,830 --> 00:33:25,895 most of the Earth's crust is 918 00:33:25,929 --> 00:33:29,095 made. 919 00:33:29,196 --> 00:33:30,796 >> A microscope reveals the 920 00:33:30,830 --> 00:33:32,263 crystalline structure of the 921 00:33:32,297 --> 00:33:34,631 granite. The crystals make the 922 00:33:34,665 --> 00:33:36,664 rocks tough, but they have a 923 00:33:36,732 --> 00:33:38,731 hidden weakness. The bonds 924 00:33:38,798 --> 00:33:40,098 between them may suddenly 925 00:33:40,199 --> 00:33:42,166 crack under stress. 926 00:33:42,200 --> 00:33:43,266 >> Basically, once this 927 00:33:43,300 --> 00:33:45,566 material solidifies, uh, it is 928 00:33:45,634 --> 00:33:48,833 able to, uh, um, crack and be, 929 00:33:48,902 --> 00:33:50,735 uh, sheared on the fault 930 00:33:50,836 --> 00:33:52,067 surface, and the brittle 931 00:33:52,101 --> 00:33:53,101 behavior of these rocks is 932 00:33:53,201 --> 00:33:55,469 what lies behind the physics 933 00:33:55,536 --> 00:33:57,536 of Earthquakes. 934 00:33:57,637 --> 00:33:59,369 >> Granite rocks underlie all 935 00:33:59,470 --> 00:34:01,170 of the San Andreas Fault, but 936 00:34:01,270 --> 00:34:02,904 right here, the rock's under 937 00:34:02,970 --> 00:34:04,471 greater stress than anywhere 938 00:34:04,539 --> 00:34:06,337 else, because it's so many 939 00:34:06,372 --> 00:34:08,005 centuries since a major quake 940 00:34:08,106 --> 00:34:10,005 occurred. 941 00:34:10,106 --> 00:34:11,105 >> And now we're over the 942 00:34:11,173 --> 00:34:13,338 300-year limit, and so it means 943 00:34:13,373 --> 00:34:15,273 that, uh, the strain, the 944 00:34:15,340 --> 00:34:16,641 amount of strain that has been 945 00:34:16,742 --> 00:34:17,908 accumulated on the fault at 946 00:34:17,974 --> 00:34:20,374 this point is very close to 947 00:34:20,442 --> 00:34:21,707 the maximum strain that this 948 00:34:21,742 --> 00:34:23,009 Fault has ever seen through 949 00:34:23,077 --> 00:34:24,909 its, uh, geologic record. 950 00:34:25,010 --> 00:34:25,909 And this is a fault that is 951 00:34:26,009 --> 00:34:27,643 capable of generating great 952 00:34:27,709 --> 00:34:31,177 destructive Earthquakes. 953 00:34:31,244 --> 00:34:32,811 >> Fialko believes the coming 954 00:34:32,878 --> 00:34:34,177 quake could be "the big one" 955 00:34:34,278 --> 00:34:35,711 that people have been talking 956 00:34:35,778 --> 00:34:37,611 about for years. And the 957 00:34:37,646 --> 00:34:39,344 effects could be horrific 958 00:34:39,412 --> 00:34:40,478 because of the population 959 00:34:40,512 --> 00:34:41,479 density of southern 960 00:34:41,513 --> 00:34:45,480 California. When the last huge 961 00:34:45,514 --> 00:34:47,580 quake occurred 300 years ago, 962 00:34:47,614 --> 00:34:49,581 Los Angeles was just a tiny 963 00:34:49,681 --> 00:34:51,314 Spanish mission community with 964 00:34:51,415 --> 00:34:53,315 fewer than 100 people. 965 00:34:55,783 --> 00:34:57,116 Now, it's America's 966 00:34:57,150 --> 00:34:58,949 second-largest city, with 967 00:34:59,050 --> 00:35:01,050 almost 11 million people living 968 00:35:01,150 --> 00:35:02,584 in the Earthquake-vulnerable 969 00:35:02,652 --> 00:35:04,617 Metropolitan area. 970 00:35:06,318 --> 00:35:07,318 >> People who live in 971 00:35:07,386 --> 00:35:09,519 California probably experience 972 00:35:09,587 --> 00:35:11,220 a small or a moderate size 973 00:35:11,288 --> 00:35:12,685 earthquake every year, a few 974 00:35:12,786 --> 00:35:14,419 things moving in your house, 975 00:35:14,487 --> 00:35:16,054 but it's really actually kind 976 00:35:16,121 --> 00:35:17,320 of fun, there is no major 977 00:35:17,388 --> 00:35:19,587 destruction. Um, people just 978 00:35:19,688 --> 00:35:21,288 go on with their life. Uh, 979 00:35:21,322 --> 00:35:22,588 much bigger events, on the 980 00:35:22,689 --> 00:35:23,756 other hand, are quite a bit 981 00:35:23,790 --> 00:35:25,422 different story. 982 00:35:27,324 --> 00:35:28,557 >> With the threat to Los 983 00:35:28,591 --> 00:35:30,424 Angeles becoming ever clearer, 984 00:35:30,491 --> 00:35:32,058 the investigation is nearing 985 00:35:32,126 --> 00:35:35,224 its conclusion. Data from 986 00:35:35,292 --> 00:35:36,958 repeated gps measurements in 987 00:35:37,026 --> 00:35:38,592 the desert reveal evidence 988 00:35:38,660 --> 00:35:41,459 that stress is building up, 989 00:35:41,493 --> 00:35:42,860 while examination of the rocks 990 00:35:42,961 --> 00:35:44,661 of the crust show they may not 991 00:35:44,728 --> 00:35:46,194 take the strain for much 992 00:35:46,228 --> 00:35:48,195 longer. 993 00:35:53,230 --> 00:35:54,829 All the evidence points 994 00:35:54,863 --> 00:35:56,463 towards a potentially huge 995 00:35:56,497 --> 00:35:59,296 earthquake building up in 996 00:35:59,330 --> 00:36:01,564 Southern California. 997 00:36:03,033 --> 00:36:04,999 And new experiments suggest 998 00:36:05,033 --> 00:36:06,731 the coming quake could be far 999 00:36:06,766 --> 00:36:09,232 worse than anyone had ever 1000 00:36:09,301 --> 00:36:11,301 imagined. 1001 00:36:22,363 --> 00:36:23,863 There is new urgency in the 1002 00:36:23,898 --> 00:36:25,363 investigation into the San 1003 00:36:25,432 --> 00:36:27,063 Andreas Fault as revealed by 1004 00:36:27,164 --> 00:36:28,797 recent evidence compiled by 1005 00:36:28,864 --> 00:36:30,265 300 of America's most 1006 00:36:30,365 --> 00:36:32,365 respected scientists. 1007 00:36:34,132 --> 00:36:35,699 They warn that Los Angeles 1008 00:36:35,800 --> 00:36:37,266 will be devastated if a major 1009 00:36:37,367 --> 00:36:38,499 quake strikes along the 1010 00:36:38,534 --> 00:36:39,700 Southern section of the 1011 00:36:39,801 --> 00:36:41,801 Fault line. 1012 00:36:43,168 --> 00:36:44,134 While there hasn't been a 1013 00:36:44,169 --> 00:36:45,535 major quake for hundreds of 1014 00:36:45,602 --> 00:36:47,634 years, even small ones can 1015 00:36:47,702 --> 00:36:49,969 still be deadly, like the 1016 00:36:50,070 --> 00:36:51,437 Northridge Earthquake, which 1017 00:36:51,504 --> 00:36:54,769 struck this L.A. suburb in 1994. 1018 00:36:59,339 --> 00:37:00,904 Rupturing along an offshoot of 1019 00:37:00,972 --> 00:37:02,771 the main San Andreas Fault, 1020 00:37:02,806 --> 00:37:04,439 the quake was only a magnitude 1021 00:37:04,506 --> 00:37:07,073 6.7, considered moderate on 1022 00:37:07,174 --> 00:37:08,239 the scale of Earthquake 1023 00:37:08,341 --> 00:37:09,773 Measurement. 1024 00:37:12,076 --> 00:37:14,507 But it still killed 72 people 1025 00:37:14,542 --> 00:37:17,141 and injured 12,000 more. 1026 00:37:18,510 --> 00:37:20,709 And new evidence suggests 1027 00:37:20,810 --> 00:37:22,242 Mother nature might have a lot 1028 00:37:22,310 --> 00:37:25,445 more in store for Los Angeles. 1029 00:37:33,879 --> 00:37:35,612 Scientists have long known 1030 00:37:35,680 --> 00:37:37,081 that Earthquakes generate 1031 00:37:37,147 --> 00:37:38,580 several distinct sets of 1032 00:37:38,614 --> 00:37:41,780 waves. They travel at 1033 00:37:41,848 --> 00:37:43,349 different speeds, each 1034 00:37:43,416 --> 00:37:44,349 spreading damage and 1035 00:37:44,416 --> 00:37:45,716 destruction out from the 1036 00:37:45,782 --> 00:37:47,415 epicenter. 1037 00:37:49,249 --> 00:37:50,683 Modern city buildings in 1038 00:37:50,718 --> 00:37:52,317 earthquake-prone areas like 1039 00:37:52,352 --> 00:37:54,150 California are engineered to 1040 00:37:54,218 --> 00:37:57,218 cope with such waves. 1041 00:37:57,285 --> 00:37:58,452 Now, new research by 1042 00:37:58,486 --> 00:38:00,085 Geophysicist professor Ares 1043 00:38:00,119 --> 00:38:02,119 Rosakis suggests that the San 1044 00:38:02,187 --> 00:38:04,020 Andreas may offer a new and 1045 00:38:04,121 --> 00:38:06,654 even more deadly threat. 1046 00:38:08,921 --> 00:38:10,355 Rosakis researches how 1047 00:38:10,389 --> 00:38:11,855 earthquakes rupture along 1048 00:38:11,923 --> 00:38:13,587 straight-line faults, just 1049 00:38:13,656 --> 00:38:15,121 like the San Andreas where it 1050 00:38:15,189 --> 00:38:17,022 approaches Los Angeles. 1051 00:38:18,391 --> 00:38:20,123 He creates his own 1052 00:38:20,191 --> 00:38:21,924 mini-earthquakes, representing 1053 00:38:21,992 --> 00:38:23,725 the San Andreas Fault by a 1054 00:38:23,758 --> 00:38:25,258 hairline crack in a thick, 1055 00:38:25,326 --> 00:38:27,424 transparent block. 1056 00:38:29,793 --> 00:38:31,593 This special material shows up 1057 00:38:31,627 --> 00:38:32,993 internal stress lines when 1058 00:38:33,094 --> 00:38:35,227 It's lit by a laser. 1059 00:38:37,161 --> 00:38:38,494 And the Earthquake is 1060 00:38:38,528 --> 00:38:40,894 triggered by a tiny explosion. 1061 00:38:42,129 --> 00:38:45,329 >> Three, two, one, zero. 1062 00:38:46,497 --> 00:38:49,696 The node has dropped, and the 1063 00:38:49,797 --> 00:38:50,997 explosion was big enough that 1064 00:38:51,064 --> 00:38:52,999 we even have a crack. 1065 00:38:53,066 --> 00:38:54,798 >> An ultra-high-speed camera 1066 00:38:54,898 --> 00:38:56,431 capturing ten million frames a 1067 00:38:56,533 --> 00:38:58,532 second, reveals a startling 1068 00:38:58,633 --> 00:38:59,766 and newly discovered 1069 00:38:59,800 --> 00:39:01,399 phenomenon. 1070 00:39:02,801 --> 00:39:04,601 This frozen picture reveals 1071 00:39:04,634 --> 00:39:06,167 stress lines speeding along the 1072 00:39:06,235 --> 00:39:07,600 mini San Andreas in the 1073 00:39:07,634 --> 00:39:09,068 milliseconds after the 1074 00:39:09,169 --> 00:39:10,768 explosion. 1075 00:39:13,336 --> 00:39:14,602 The cone to the left of this 1076 00:39:14,703 --> 00:39:16,168 frame is a previously 1077 00:39:16,237 --> 00:39:18,404 unrecognized type of shockwave 1078 00:39:18,437 --> 00:39:19,971 racing along the rupture line 1079 00:39:20,039 --> 00:39:22,604 from the Earthquake center. 1080 00:39:22,705 --> 00:39:24,605 On a microscopic scale, it 1081 00:39:24,706 --> 00:39:26,406 looks and moves exactly like 1082 00:39:26,440 --> 00:39:28,338 the sonic boom produced when a 1083 00:39:28,439 --> 00:39:30,139 supersonic aircraft, such as 1084 00:39:30,240 --> 00:39:31,706 Concorde, breaks the sound 1085 00:39:31,807 --> 00:39:32,807 barrier. 1086 00:39:32,874 --> 00:39:34,140 >> Because we also see mach 1087 00:39:34,241 --> 00:39:36,241 cones, lines that are emitted 1088 00:39:36,341 --> 00:39:38,341 from the rupture tips, as from 1089 00:39:38,442 --> 00:39:41,775 the tips of moving airplanes. 1090 00:39:41,809 --> 00:39:43,509 >> And, just like a sonic 1091 00:39:43,610 --> 00:39:46,611 boom, it can be dangerous. 1092 00:39:46,678 --> 00:39:47,710 >> In the same sense that we 1093 00:39:47,778 --> 00:39:50,311 hear the sonic boom, uh, from 1094 00:39:50,345 --> 00:39:51,711 the Concorde, you are going to 1095 00:39:51,779 --> 00:39:53,779 feel the sonic boom from the 1096 00:39:53,880 --> 00:39:54,778 rupture. 1097 00:39:54,879 --> 00:39:56,045 >> The danger comes because 1098 00:39:56,079 --> 00:39:57,779 many high rises just aren't 1099 00:39:57,880 --> 00:39:59,313 built to cope with extra 1100 00:39:59,347 --> 00:40:00,980 stress from this newly 1101 00:40:01,047 --> 00:40:03,314 discovered type of shockwave. 1102 00:40:03,347 --> 00:40:04,314 >> So if you are an old 1103 00:40:04,348 --> 00:40:07,148 building, for example, uh, 1104 00:40:07,217 --> 00:40:08,848 you'll shake one way, you will 1105 00:40:08,882 --> 00:40:11,683 accumulate some damage, and, 1106 00:40:11,751 --> 00:40:14,116 uh, very soon after that, you 1107 00:40:14,150 --> 00:40:15,983 will get very strong ground 1108 00:40:16,050 --> 00:40:18,151 shaking because of other types 1109 00:40:18,219 --> 00:40:20,051 of waves coming also. 1110 00:40:22,152 --> 00:40:23,419 >> The high-speed ruptures 1111 00:40:23,519 --> 00:40:25,419 that Rosakis calls supershear 1112 00:40:25,487 --> 00:40:27,220 happen where faults run in a 1113 00:40:27,321 --> 00:40:29,220 straight line... 1114 00:40:31,855 --> 00:40:33,222 which might help explain a 1115 00:40:33,322 --> 00:40:34,787 100-year-old mystery 1116 00:40:34,855 --> 00:40:35,788 surrounding the great 1117 00:40:35,856 --> 00:40:37,756 San Francisco quake, the 1118 00:40:37,790 --> 00:40:39,122 natural disaster which 1119 00:40:39,156 --> 00:40:40,523 launched the entire San 1120 00:40:40,591 --> 00:40:42,789 Andreas investigation. 1121 00:40:46,658 --> 00:40:48,491 The overwhelming damage in San 1122 00:40:48,525 --> 00:40:50,125 Francisco has long seemed 1123 00:40:50,159 --> 00:40:51,858 surprisingly out of proportion 1124 00:40:51,926 --> 00:40:53,926 to the 7.8 magnitude of the 1125 00:40:53,961 --> 00:40:57,394 quake. And there's a 1126 00:40:57,428 --> 00:40:59,128 particularly straight section 1127 00:40:59,228 --> 00:41:01,060 of the San Andreas approaching 1128 00:41:01,128 --> 00:41:04,495 San Francisco. So, many 1129 00:41:04,596 --> 00:41:06,329 scientists now believe that 1130 00:41:06,397 --> 00:41:07,496 the damage was greater than 1131 00:41:07,597 --> 00:41:10,462 expected because the 1906 quake 1132 00:41:10,497 --> 00:41:12,196 had traveled at supershear 1133 00:41:12,231 --> 00:41:13,864 speed. 1134 00:41:15,865 --> 00:41:17,498 Of greater concern to modern 1135 00:41:17,565 --> 00:41:19,464 emergency services is not what 1136 00:41:19,499 --> 00:41:21,297 happened a century ago, but 1137 00:41:21,332 --> 00:41:24,766 what could happen tomorrow, 1138 00:41:24,867 --> 00:41:26,299 because there is a similar 1139 00:41:26,367 --> 00:41:27,667 straight section of faulted 1140 00:41:27,769 --> 00:41:29,133 ground heading straight 1141 00:41:29,234 --> 00:41:32,868 towards Los Angeles, and if a 1142 00:41:32,935 --> 00:41:34,734 supershear Earthquake develops 1143 00:41:34,769 --> 00:41:36,168 on that line, then the 1144 00:41:36,236 --> 00:41:37,669 consequences could be 1145 00:41:37,737 --> 00:41:38,736 disastrous. 1146 00:41:39,871 --> 00:41:41,104 >> Here we go. 1147 00:41:41,139 --> 00:41:42,203 >> All of the investigation's 1148 00:41:42,271 --> 00:41:43,871 warnings about the San Andreas 1149 00:41:43,938 --> 00:41:45,303 came together in the fall of 1150 00:41:45,371 --> 00:41:47,138 2008, with the biggest 1151 00:41:47,205 --> 00:41:48,837 earthquake drill ever held in 1152 00:41:48,938 --> 00:41:50,205 California. 1153 00:41:50,273 --> 00:41:51,406 >> If this Earthquake would 1154 00:41:51,473 --> 00:41:52,939 have happened in reality, 1155 00:41:53,041 --> 00:41:54,206 there--there would have been 1156 00:41:54,274 --> 00:41:55,773 buildings coming down, we know 1157 00:41:55,840 --> 00:41:56,906 that there would be no water 1158 00:41:56,940 --> 00:41:58,474 now in certain areas, that's 1159 00:41:58,574 --> 00:41:59,740 what this exercise is all 1160 00:41:59,775 --> 00:42:01,573 about. 1161 00:42:01,642 --> 00:42:02,841 >> But what are the real 1162 00:42:02,942 --> 00:42:04,675 chances of Los Angeles soon 1163 00:42:04,777 --> 00:42:06,109 being hit by a massive 1164 00:42:06,210 --> 00:42:09,109 earthquake? Frighteningly, the 1165 00:42:09,210 --> 00:42:11,044 best scientific consensus now 1166 00:42:11,111 --> 00:42:12,844 warns that there's a 99 per 1167 00:42:12,944 --> 00:42:14,943 cent chance of a major quake 1168 00:42:15,011 --> 00:42:16,477 in Southern California within 1169 00:42:16,545 --> 00:42:20,212 the next 30 years. To better 1170 00:42:20,280 --> 00:42:21,945 understand the threat to L.A., 1171 00:42:22,013 --> 00:42:23,679 the geologists produced their 1172 00:42:23,747 --> 00:42:25,646 study jointly with experts in 1173 00:42:25,680 --> 00:42:27,380 charge of the city's disaster 1174 00:42:27,448 --> 00:42:29,680 planning. And none of them 1175 00:42:29,748 --> 00:42:31,314 doubt that the big quake is 1176 00:42:31,382 --> 00:42:32,949 coming. 1177 00:42:33,017 --> 00:42:34,116 >> It really isn't even a 1178 00:42:34,183 --> 00:42:36,582 question of if anymore. 1179 00:42:39,017 --> 00:42:40,750 The shaking is going to be 1180 00:42:40,818 --> 00:42:42,483 severe for two to three 1181 00:42:42,584 --> 00:42:44,217 minutes. 1182 00:42:46,486 --> 00:42:49,019 And then it's gonna stop, 1183 00:42:49,087 --> 00:42:50,119 and then you're gonna have that 1184 00:42:50,187 --> 00:42:51,186 moment of silence that often 1185 00:42:51,220 --> 00:42:52,853 happens before you start 1186 00:42:52,921 --> 00:42:55,753 hearing the car alarms, all 1187 00:42:55,821 --> 00:42:56,753 those other sounds that you 1188 00:42:56,821 --> 00:42:58,221 have in a disaster like this. 1189 00:42:58,289 --> 00:42:59,721 >> The study estimates that a 1190 00:42:59,756 --> 00:43:01,189 major Earthquake in the L.A. 1191 00:43:01,256 --> 00:43:03,922 Metro area would cause 2,000 1192 00:43:03,990 --> 00:43:06,656 deaths, 50,000 injuries and 1193 00:43:06,724 --> 00:43:10,456 200 billion dollars of damage. 1194 00:43:10,491 --> 00:43:11,458 >> You're going to have 1195 00:43:11,526 --> 00:43:13,091 conflagrations developing, 1196 00:43:13,125 --> 00:43:14,825 tens of blocks will be on fire. 1197 00:43:14,926 --> 00:43:15,824 >> Reporter: The water lines 1198 00:43:15,926 --> 00:43:17,025 have ruptured, there is no 1199 00:43:17,093 --> 00:43:18,125 water coming out of the fire 1200 00:43:18,193 --> 00:43:19,125 hydrants. 1201 00:43:19,193 --> 00:43:20,126 >> That's the kind of nightmare 1202 00:43:20,194 --> 00:43:22,025 scenario that we're looking at. 1203 00:43:26,729 --> 00:43:28,395 >> This specter of disaster to 1204 00:43:28,463 --> 00:43:30,362 California's people and cities 1205 00:43:30,463 --> 00:43:31,662 motivates the search to 1206 00:43:31,730 --> 00:43:33,296 unravel the secrets of the San 1207 00:43:33,364 --> 00:43:35,530 Andreas Fault. All the 1208 00:43:35,564 --> 00:43:38,531 evidence is finally in. 1209 00:43:38,565 --> 00:43:39,731 The damage reports from the 1210 00:43:39,831 --> 00:43:41,998 1906 disaster show the fault's 1211 00:43:42,066 --> 00:43:45,832 800-mile path. The different 1212 00:43:45,933 --> 00:43:47,633 types of rock at Mussel Rock 1213 00:43:47,667 --> 00:43:49,199 provide clues to how the fault 1214 00:43:49,267 --> 00:43:51,100 was created 20 million years 1215 00:43:51,201 --> 00:43:54,901 ago. The river bends prove how 1216 00:43:54,935 --> 00:43:58,635 fast the land is moving. The 1217 00:43:58,702 --> 00:44:00,636 mineral talc explains why some 1218 00:44:00,703 --> 00:44:02,636 parts slip without major 1219 00:44:02,703 --> 00:44:05,537 quakes. The brittle granite 1220 00:44:05,638 --> 00:44:07,570 rocks reveal a threat to Los 1221 00:44:07,638 --> 00:44:10,904 Angeles, and recent lab 1222 00:44:11,005 --> 00:44:13,106 experiments uncover new and 1223 00:44:13,174 --> 00:44:14,739 more dangerous Earthquake 1224 00:44:14,807 --> 00:44:16,372 Shockwaves. 1225 00:44:19,074 --> 00:44:21,474 But one goal has eluded the 1226 00:44:21,542 --> 00:44:23,374 rock detectives who study 1227 00:44:23,442 --> 00:44:25,008 the greatest fault line on 1228 00:44:25,076 --> 00:44:26,975 Earth. 1229 00:44:29,810 --> 00:44:31,675 When will the sleeping San 1230 00:44:31,743 --> 00:44:33,609 Andreas come to life once 1231 00:44:33,645 --> 00:44:39,278 again? It could be any time. 1232 00:44:39,379 --> 00:44:41,279 The only certainty is that 1233 00:44:41,380 --> 00:44:42,978 nothing is certain in the 1234 00:44:43,013 --> 00:44:45,646 ever-evolving story of how the 1235 00:44:45,713 --> 00:44:47,913 Earth was made.