WEBVTT - What Is the Deepest Hole in the World? 0:00:01.840 --> 0:00:07.600 Welcome to Brainstuff, a production of iHeartRadio. Hey brain Stuff 0:00:07.680 --> 0:00:12.040 Lauren Bogelbaum here. In the decades after World War Two, 0:00:12.440 --> 0:00:15.840 the United States and the USSR locked into the space 0:00:15.960 --> 0:00:19.400 race to orbit and the Moon, but they were also 0:00:19.560 --> 0:00:22.759 vying to outdo each other in another race, one to 0:00:22.840 --> 0:00:25.800 the center of the Earth, or at least as close 0:00:25.800 --> 0:00:29.960 to it as possible. This resulted in the deepest hole 0:00:30.080 --> 0:00:34.680 in the world today, let's talk about the Cola Super 0:00:34.680 --> 0:00:41.639 Deep Borehole. Okay. In nineteen fifty eight, America launched Project Mohole, 0:00:42.080 --> 0:00:45.239 a plan to retrieve a sample from Earth's mantle by 0:00:45.320 --> 0:00:47.600 drilling to the bottom of the Pacific Ocean off of 0:00:47.600 --> 0:00:52.159 Guadalupe Island, Mexico. With funds from the National Science Foundation, 0:00:52.440 --> 0:00:55.280 they drilled six hundred and one feet that's one hundred 0:00:55.280 --> 0:00:58.200 and eighty three meters into the seabed before funding for 0:00:58.240 --> 0:01:02.000 the project was pulled in nineteen six sixty six. In 0:01:02.080 --> 0:01:06.000 nineteen seventy, the Soviets launched their attempt, drilling into the 0:01:06.000 --> 0:01:09.600 ground on the Cola Peninsula in the northwestern corner of Russia, 0:01:09.840 --> 0:01:13.800 just off the Norwegian border, near the Barren Sea. They 0:01:13.880 --> 0:01:18.160 were more successful, penetrating much deeper and collecting samples that 0:01:18.360 --> 0:01:22.920 still whole scientists. If you've visited the site today and 0:01:23.200 --> 0:01:27.080 you can it's a tourist attraction. Now, it might seem underwhelming, 0:01:28.160 --> 0:01:31.160 hidden in an abandoned work site, among rotting wood and 0:01:31.240 --> 0:01:34.560 sheets of scrap metal remains of the housing and drilling 0:01:34.600 --> 0:01:39.319 framework that once stood. There sits a small, unassuming, heavy 0:01:39.360 --> 0:01:43.160 duty metal cover secured into place with a dozen large 0:01:43.240 --> 0:01:47.880 resting bolts. Underneath this bottle cap is a hole that's 0:01:47.920 --> 0:01:51.600 just nine inches that's twenty three centimeters in diameter, but 0:01:51.840 --> 0:01:56.920 remains the world's deepest man made hole. It's actually the 0:01:57.000 --> 0:02:00.840 deepest point that we know of in the Earth. The 0:02:01.000 --> 0:02:04.520 Cola Super Deep Borehole runs about seven point six miles 0:02:04.720 --> 0:02:09.440 that's twelve point three kilometers into Earth's surface. For perspective, 0:02:09.919 --> 0:02:12.600 the hole's depth is the height of Mount Everest and 0:02:12.720 --> 0:02:16.560 Mount Fuji stacked on top of one another. It's deeper 0:02:16.600 --> 0:02:19.160 than the deepest point of the Ocean, the Marianna Trench, 0:02:19.440 --> 0:02:22.079 which dips a mirror six point eight miles or ten 0:02:22.120 --> 0:02:26.640 point nine kilometers below the surface of the Pacific. Drilling 0:02:26.680 --> 0:02:29.720 at Cola began on May twenty fourth of nineteen seventy 0:02:30.639 --> 0:02:33.560 The goal was to go as far as possible, which 0:02:33.600 --> 0:02:36.640 scientists at the time hoped to be about nine miles 0:02:36.720 --> 0:02:41.480 or fifteen kilometers. By nineteen seventy nine, the project had 0:02:41.520 --> 0:02:44.600 broken all world records for man made holes when it 0:02:44.600 --> 0:02:47.480 surpassed about six miles or nine and a half kilometers. 0:02:48.280 --> 0:02:52.160 In nineteen eighty nine, they reached the current depth. That's 0:02:52.240 --> 0:02:55.200 when temperatures in the well increased to three hundred and 0:02:55.280 --> 0:02:59.320 fifty six degrees fahrenheit or one eighty celsius, forcing work 0:02:59.400 --> 0:03:02.600 to stop. Turns out that digging a hole to the 0:03:02.639 --> 0:03:04.640 center of the Earth is a bit trickier than the 0:03:04.639 --> 0:03:09.520 researchers expected. When drilling began at Cola, the granite near 0:03:09.560 --> 0:03:13.400 the surface was easy going, but when drillers reached about 0:03:13.400 --> 0:03:16.240 four point three miles or six point nine kilometers deep, 0:03:16.720 --> 0:03:20.120 the layers became more dense and difficult to bore into. 0:03:20.840 --> 0:03:23.280 Drill bits broke, and the team had to change the 0:03:23.320 --> 0:03:26.160 direction of the drilling several times, meaning that there are 0:03:26.200 --> 0:03:29.280 a few branches off of the central hole. The resulting 0:03:29.280 --> 0:03:32.760 pattern looks a little like a Charlie Brown Christmas tree. 0:03:32.919 --> 0:03:35.800 The engineers plowed on, but the deeper they went the 0:03:35.880 --> 0:03:40.240 hotter the earth became. The temperature gradient conformed to what 0:03:40.320 --> 0:03:43.240 scientists had predicted to a certain point, but then the 0:03:43.280 --> 0:03:47.360 heat intensified. They weren't expecting anything higher than the boiling 0:03:47.400 --> 0:03:50.200 point of water, which is two twelve fahrenheit or one 0:03:50.280 --> 0:03:54.839 hundred celsius. When the temperature climbed eighty percent higher than that, 0:03:55.480 --> 0:03:59.200 the rock, which was also more porous that expected, started 0:03:59.240 --> 0:04:02.960 behaving more like a plastic that a solid, rendering drilling 0:04:03.360 --> 0:04:08.520 virtually impossible. Although the team pressed on until nineteen ninety two, 0:04:09.080 --> 0:04:11.200 they never got any deeper than what they reached. In 0:04:11.280 --> 0:04:15.080 nineteen eighty nine. The drill site was officially shut down 0:04:15.160 --> 0:04:17.799 and the hole sealed over in two thousand and five. 0:04:19.320 --> 0:04:23.240 But okay, why would anyone go to the trouble of 0:04:23.320 --> 0:04:27.719 doing this? Of course, humans dig holes for various reasons, 0:04:28.120 --> 0:04:31.920 most notably for extracting resources like fossil fuels and metals. 0:04:32.800 --> 0:04:35.560 For example, in the United States, there's the Bingham Canyon 0:04:35.600 --> 0:04:38.360 copper mine in the mountains near Salt Lake City, the 0:04:38.400 --> 0:04:40.640 site of a pit that extends three quarters of a 0:04:40.640 --> 0:04:44.880 mile deep that's one point two kilometers, and Oklahoma's Bertha 0:04:44.960 --> 0:04:48.120 Rogers gas well, which goes down about six miles or 0:04:48.279 --> 0:04:51.120 nine point six kilometers and had to stop because they 0:04:51.200 --> 0:04:55.919 hit liquid sulfur. The colibor hole was partially looking for 0:04:55.960 --> 0:04:58.320 the presence of metals and minerals down in the layers 0:04:58.360 --> 0:05:02.720 of Earth to help locate their deposits, but holes are 0:05:02.760 --> 0:05:05.320 also dug in the name of science to learn more 0:05:05.360 --> 0:05:10.720 about hazards like earthquakes and volcanic eruptions, resources like geothermal 0:05:10.760 --> 0:05:14.200 heat and energy, the evolution of our planet and the 0:05:14.240 --> 0:05:17.840 life on it, and the environmental changes of the past 0:05:18.040 --> 0:05:22.560 to better project into the future. For the article of 0:05:22.600 --> 0:05:24.880 this episode is based on how Stuff Works. Spoke with 0:05:24.920 --> 0:05:28.960 doctor Ulrich Hahnes, now the Liaison officer for the International 0:05:29.000 --> 0:05:33.240 Continental Scientific Drilling Program at the GFC Hemholtz Center for 0:05:33.320 --> 0:05:38.159 Geosciences in Germany. He's visited the Colobar Hoole, browsed the 0:05:38.200 --> 0:05:41.760 repository of core samples, and even laid hands on the 0:05:41.800 --> 0:05:47.440 now defunct well head. He explained one example in detail 0:05:47.720 --> 0:05:51.320 is that observations very close to an earthquake zone allow 0:05:51.440 --> 0:05:55.760 researchers to monitor the initiation and propagation of even the 0:05:55.800 --> 0:06:00.360 tiniest earthquake. In response to stress and strain We want 0:06:00.360 --> 0:06:04.800 to recover these near field physical, chemical, and mechanical data 0:06:04.839 --> 0:06:08.919 to fundamentally understand these processes that cannot be simplified in 0:06:09.000 --> 0:06:15.200 lab experiments or computer models. In nineteen seventy, when work 0:06:15.240 --> 0:06:18.400 on the Colo Peninsula began, the idea that the Earth 0:06:18.440 --> 0:06:21.960 has layers made up of different materials in different conditions 0:06:22.240 --> 0:06:27.040 was relatively new. Until the late eighteen hundreds, scientists believed 0:06:27.040 --> 0:06:30.240 that Earth's composition was the same from crust to core. 0:06:31.440 --> 0:06:35.440 But as the technology advanced to measure earthquakes, you know, 0:06:35.600 --> 0:06:40.360 seismic waves moving through the Earth, researchers discovered something bewildering. 0:06:41.320 --> 0:06:44.200 There was a sudden increase in the velocity of seismic 0:06:44.279 --> 0:06:46.800 waves as they passed from what we now know is 0:06:46.880 --> 0:06:50.160 the thin solid crust at the Earth that we stand on, 0:06:50.560 --> 0:06:56.080 to the underlying liquid mantle. If Earth's interior was made 0:06:56.160 --> 0:06:58.279 up of the same material all the way through, the 0:06:58.320 --> 0:07:01.760 waves should have been proportional to their distance. In other words, 0:07:01.839 --> 0:07:04.559 they should have moved gradually slower as they got further 0:07:04.600 --> 0:07:09.160 away from the quake's epicenter. But instead they started traveling faster. 0:07:10.320 --> 0:07:14.280 The seismic waves are refracted faster through denser materials, so 0:07:14.600 --> 0:07:18.800 researchers realized that those faster moving waves must have encountered 0:07:18.840 --> 0:07:22.920 a denser layer of Earth. This was first observed by 0:07:22.960 --> 0:07:26.920 a Croatian meteorologist and seismologist by the name of Andrea 0:07:27.040 --> 0:07:30.520 Mohorovicic in nineteen oh nine, who went on to publish 0:07:30.520 --> 0:07:34.440 his hypothesis about there being a discernible dividing line between 0:07:34.440 --> 0:07:38.960 Earth's crust and mantle a decade later. This boundary zone 0:07:39.000 --> 0:07:43.040 is known today as the Mohorovicic discontinuity or the MOHO 0:07:43.760 --> 0:07:47.600 It's what the American drilling team named Project Mohole after. 0:07:49.200 --> 0:07:53.480 Throughout the nineteen fifties and sixties, another earth shattering hypothesis 0:07:53.600 --> 0:07:58.880 was emerging. The idea of plate tectonics. The more general 0:07:58.920 --> 0:08:01.840 theory that the continents are aren't fixed, but rather shift 0:08:01.960 --> 0:08:05.200 over eons of time, went back to nineteen twelve, but 0:08:05.240 --> 0:08:08.120 it wasn't until nineteen fifty six, during a survey of 0:08:08.160 --> 0:08:12.000 the Pacific Ocean floor, that scientists observed real evidence of 0:08:12.040 --> 0:08:15.120 this in the form of on opposite sides of a 0:08:15.240 --> 0:08:21.560 ridge on the seafloor symmetrical magnetic reversals, meaning that both 0:08:21.720 --> 0:08:24.480 sides had been formed at the same time from the 0:08:24.520 --> 0:08:28.920 ridge line and then spread apart from each other. So 0:08:29.440 --> 0:08:33.840 when Project Mohole and the Cola Borehole began work, digging 0:08:33.880 --> 0:08:37.600 deep was an exciting field of study and a flex 0:08:37.720 --> 0:08:41.320 of a country's capacity with tech and engineering, similar to 0:08:41.360 --> 0:08:44.679 the space race. We knew even then that the Earth's 0:08:44.720 --> 0:08:48.160 crust must be relatively thin. On average, we think it's 0:08:48.160 --> 0:08:51.360 about twenty five miles thick. That's forty kilometers, though it 0:08:51.400 --> 0:08:54.520 tends to be thinner under the ocean floor and perhaps 0:08:54.559 --> 0:08:58.280 obviously is thicker when you come across a mountain range. 0:08:58.520 --> 0:09:00.760 The Cola team was hoping to dig down a little 0:09:00.800 --> 0:09:03.440 over a third of that, but got stuck a little 0:09:03.600 --> 0:09:07.680 under a third. The next layer down the mantle is 0:09:07.760 --> 0:09:11.640 probably the thickest layer. It should continue for another one thousand, 0:09:11.720 --> 0:09:15.320 eight hundred miles or three thousand kilometers, and seems to 0:09:15.440 --> 0:09:19.320 consist of hot, dense rock that flows like asphalt and 0:09:19.440 --> 0:09:23.560 moves the plates of the crust around. Underneath that, we 0:09:23.600 --> 0:09:26.560 think that there is the liquid metal outer core, which 0:09:26.600 --> 0:09:29.560 descends another one thousand, four hundred miles or two thousand, 0:09:29.600 --> 0:09:33.240 two hundred kilometers or so, and then the solid metal 0:09:33.360 --> 0:09:37.360 inner core, a hot dense ball of mostly iron with 0:09:37.440 --> 0:09:40.200 a radius of about eight hundred miles or one thousand, 0:09:40.240 --> 0:09:45.640 two hundred kilometers. So while the super Deep Borehole is impressive, 0:09:46.080 --> 0:09:48.880 it only penetrates less than a third of Earth's crust 0:09:49.200 --> 0:09:52.240 and just zero point two percent of the entire distance 0:09:52.280 --> 0:09:56.000 to the center of the Earth. And until we actually 0:09:56.040 --> 0:09:59.360 physically interact with these layers, we won't know for sure 0:09:59.400 --> 0:10:02.520 what they're made up above in what conditions those materials 0:10:02.559 --> 0:10:06.640 are under. Other attempts have been made through the years 0:10:06.679 --> 0:10:11.160 by other countries, including Germany, Austria, and Sweden, and a 0:10:11.200 --> 0:10:14.400 couple of oil wells have gone deep too, including one 0:10:14.400 --> 0:10:17.120 in the Persian Gulf and one off the southeast coast 0:10:17.200 --> 0:10:20.760 of Russia. None of those are deeper than the Kolo 0:10:20.840 --> 0:10:24.280 super Deep Borehole, though some are longer having veered off 0:10:24.280 --> 0:10:28.760 of their vertical courses. So we still haven't come anywhere 0:10:28.800 --> 0:10:32.959 close to reaching the Moharrevichic discontinuity and finding out whether 0:10:33.000 --> 0:10:37.000 we're right about the deeper layers of the Earth. Still, 0:10:37.160 --> 0:10:40.560 scientists discovered a lot from the Kola Boorhole and the 0:10:40.600 --> 0:10:44.560 other projects, as well a lot of today's drilling technology 0:10:44.720 --> 0:10:48.400 in use by both scientific teams and petroleum Companies, was 0:10:48.440 --> 0:10:52.080 first developed on the fly for Project Mohol or the 0:10:52.160 --> 0:10:57.079 German Continental Deep Drilling program. The Kola borhole taught us 0:10:57.160 --> 0:10:59.880 that a few of our hypotheses about the crust were wrong, 0:11:00.640 --> 0:11:04.040 like how quickly the temperature rises, and also that there's 0:11:04.040 --> 0:11:08.400 no conrad discontinuity, a transition boundary from granite rock to 0:11:08.440 --> 0:11:12.079 basalt that geologists had reasoned to exist based on results 0:11:12.080 --> 0:11:16.640 of seismic reflection surveys. The team also found liquid water 0:11:17.000 --> 0:11:21.120 far deeper than we previously thought could exist, Harms said. 0:11:21.920 --> 0:11:25.360 One of the unexpected results was certainly the occurrence of open, 0:11:25.559 --> 0:11:29.920 saline water filled cracks, documenting that the crust is not dense, 0:11:30.160 --> 0:11:35.600 but that pathways exist, allowing fluids to flow. Even more 0:11:35.600 --> 0:11:39.440 exciting was the discovery of biological activity among the rocks. 0:11:40.120 --> 0:11:43.040 At about four and a half miles down that's seven kilometers, 0:11:43.440 --> 0:11:46.920 the team found dozens of fossils from single celled marine 0:11:47.000 --> 0:11:53.320 organisms dating back two billion years. Some microscopic fossils, encased 0:11:53.360 --> 0:11:57.840 and organic compounds were surprisingly intact despite the extreme pressures 0:11:57.840 --> 0:12:03.040 and temperatures of the surrounding rock. But can we dig deeper? 0:12:04.520 --> 0:12:10.520 Probably eventually, but Harms said. Digging deeper than twelve kilometers 0:12:10.679 --> 0:12:15.600 depends on two critical factors temperature and borehole stability, the 0:12:15.679 --> 0:12:19.920 latter being dependent on stress strain and drilling fluid composition 0:12:20.040 --> 0:12:26.600 and weight. That'll take some pretty technologically advanced equipment. Considering 0:12:26.640 --> 0:12:29.079 that temperatures there are predicted to be as high as 0:12:29.120 --> 0:12:33.960 five hundred degrees fahrenheit or two fifty celsius, and the 0:12:34.000 --> 0:12:37.240 real pie in the sky, or rather pie in the 0:12:37.280 --> 0:12:42.640 Earth would be reaching Earth's mantle, Harms said, we can 0:12:42.720 --> 0:12:44.840 learn a lot about the mantle if we get access 0:12:44.880 --> 0:12:48.720 through drilling. Earth scientists want access to the real institu 0:12:48.840 --> 0:12:51.640 mantle to understand the nature of this boundary that is 0:12:51.679 --> 0:12:54.959 still debated and from which we have no fresh samples 0:12:55.000 --> 0:12:58.120 that contain information on how the crust and mantle interact, 0:12:58.559 --> 0:13:01.720 how fluids and magma droplets escape from the mantle into 0:13:01.720 --> 0:13:05.200 the crust and ultimately into our hydrosphere, and how they 0:13:05.240 --> 0:13:09.679 feed the biosphere, or how matter escapes back into the mantle. 0:13:10.400 --> 0:13:14.359 These grand circles of how our planet evolves remain enigmatic 0:13:14.400 --> 0:13:18.360 along this boundary, and moho discontinuity is therefore a prime 0:13:18.440 --> 0:13:25.120 objective of scientific exploration. But people are trying for it. 0:13:25.679 --> 0:13:28.400 In the early two thousands, Japan began work on a 0:13:28.400 --> 0:13:32.080 gigantic drilling ship called the chiqu A Japanese word for 0:13:32.160 --> 0:13:35.000 the Earth, which is designed to pick up where Project 0:13:35.080 --> 0:13:38.439 Mohol left off, going for the mantle through the relatively 0:13:38.520 --> 0:13:42.760 thin oceanic crust. This ship and others like it, have 0:13:42.840 --> 0:13:45.760 been part of several international science programs over the past 0:13:45.800 --> 0:13:50.240 couple of decades, co funded by multiple governments. In twenty 0:13:50.280 --> 0:13:52.960 twenty one, a Japanese team working with one of these, 0:13:53.080 --> 0:13:57.080 the International Ocean Discovery Program, achieved the deepest yet drill 0:13:57.160 --> 0:14:00.000 into the ocean's crust, coming in at four point nine 0:14:00.120 --> 0:14:04.760 miles or write over eight kilometers. Funding from the United 0:14:04.760 --> 0:14:08.640 States has since shifted away from scientific ventures like this again, 0:14:09.480 --> 0:14:13.960 but the international community is boring on. We'll keep you 0:14:14.040 --> 0:14:21.280 updated in the future. Today's episode is based on the 0:14:21.360 --> 0:14:23.920 article why did the Russians seal up the deepest holl 0:14:23.960 --> 0:14:26.200 in the world on how Stuffworks dot Com, written by 0:14:26.240 --> 0:14:29.640 Jennifer Walker. Journey brain Stuff is production of iHeartRadio in 0:14:29.720 --> 0:14:32.160 partnership with how Stuffworks dot Com and is produced by 0:14:32.200 --> 0:14:35.760 Tyler Quain. For more podcasts my heart Radio, visit the 0:14:35.800 --> 0:14:39.080 iHeartRadio app, Apple podcasts, or wherever you listen to your 0:14:39.080 --> 0:14:39.840 favorite shows.