1 00:00:01,920 --> 00:00:06,480 Speaker 1: Welcome to brain Stuff, a production of iHeart Radio, Hey 2 00:00:06,519 --> 00:00:10,240 Speaker 1: brain Stuff Lauren bogebam Here. Old Faithful used to have 3 00:00:10,440 --> 00:00:15,280 Speaker 1: a less than modest nickname Eternity's time Piece. Since at 4 00:00:15,360 --> 00:00:18,640 Speaker 1: least the late eighteen hundreds, this wyoming cone geyser has 5 00:00:18,640 --> 00:00:22,200 Speaker 1: wowed spectators with its predictable eruptions. You can see the 6 00:00:22,239 --> 00:00:25,200 Speaker 1: landmark for yourself in Yellowstone National Park, home to over 7 00:00:25,239 --> 00:00:28,400 Speaker 1: five hundred geysers. More than one hundred and fifty of 8 00:00:28,400 --> 00:00:32,280 Speaker 1: these water spurting marvels, including Old Faithful, occupy the park's 9 00:00:32,360 --> 00:00:36,920 Speaker 1: upper geyser basin. So named in eighteen seventy because it's 10 00:00:36,920 --> 00:00:40,720 Speaker 1: spouted at regular intervals, Old Faithful gets more fanfair than 11 00:00:40,760 --> 00:00:44,880 Speaker 1: any other geothermal attraction in the world. Visited by presidents 12 00:00:44,880 --> 00:00:49,000 Speaker 1: and immortalized by artists, the geyser spouts about seventeen times 13 00:00:49,000 --> 00:00:52,760 Speaker 1: a day. Countdown clocks tell gathering tourists when too ready 14 00:00:52,800 --> 00:00:56,480 Speaker 1: their cameras for the next waterworks show. You see. There's 15 00:00:56,520 --> 00:00:59,560 Speaker 1: a simple formula rangers used to estimate how much time 16 00:00:59,560 --> 00:01:02,880 Speaker 1: will likely elapse between any two eruptions of Old Faithful. 17 00:01:03,800 --> 00:01:07,240 Speaker 1: According to the National Park Service, about of these eruption 18 00:01:07,319 --> 00:01:10,160 Speaker 1: predictions are accurate within a window of plus or minus 19 00:01:10,200 --> 00:01:14,440 Speaker 1: ten minutes. That's a solid track record, but Old Faithful 20 00:01:14,560 --> 00:01:17,240 Speaker 1: still isn't something you'd want to set your watch by. 21 00:01:17,560 --> 00:01:21,080 Speaker 1: Five decades of observation have revealed that the geyser is changing. 22 00:01:22,319 --> 00:01:26,800 Speaker 1: Since nine, the average interval between Old Faithful's eruptions has 23 00:01:26,880 --> 00:01:30,000 Speaker 1: gotten longer, and while most of the actual eruptions which 24 00:01:30,000 --> 00:01:33,080 Speaker 1: occurred back then were rather brief, this is no longer 25 00:01:33,120 --> 00:01:37,440 Speaker 1: the case. But we spoke via email with Sin May Wu, 26 00:01:37,520 --> 00:01:39,960 Speaker 1: a geologist at the University of Utah who studied the 27 00:01:39,959 --> 00:01:44,040 Speaker 1: physics of geyser's and related structures. She said geysers are 28 00:01:44,120 --> 00:01:48,200 Speaker 1: rare because they require very unique geologic conditions, a persistent 29 00:01:48,240 --> 00:01:51,800 Speaker 1: heat source, abundant water supply from groundwater systems, and a 30 00:01:51,880 --> 00:01:55,040 Speaker 1: porous or fractured medium that allows fluid migration and heat 31 00:01:55,080 --> 00:02:00,360 Speaker 1: transfer within. Usually the heat comes from magma, a liquid 32 00:02:00,440 --> 00:02:03,120 Speaker 1: or semi liquid rock found below Earth's crust, which is 33 00:02:03,160 --> 00:02:06,920 Speaker 1: called lava once it bursts onto the surface. Yellow Stone 34 00:02:07,000 --> 00:02:10,760 Speaker 1: is positioned over two magma chambers, including a nice long 35 00:02:10,840 --> 00:02:13,760 Speaker 1: one that's just three to ten miles underground that's five 36 00:02:13,800 --> 00:02:17,880 Speaker 1: to seventeen kilometers. Their maker was a localized swell of 37 00:02:17,919 --> 00:02:22,480 Speaker 1: abnormally hot material beneath the crust, classified as a mantle plume. 38 00:02:22,720 --> 00:02:26,080 Speaker 1: It's the reason why Yellowstone has the world's largest geyser collection. 39 00:02:27,080 --> 00:02:31,799 Speaker 1: The chambers warm up subterranean reservoirs of liquid groundwater. Although 40 00:02:31,840 --> 00:02:34,720 Speaker 1: the physics here aren't entirely settled, we do know that 41 00:02:34,760 --> 00:02:38,560 Speaker 1: some of this water gets superheated. That means it's temperature 42 00:02:38,600 --> 00:02:42,960 Speaker 1: climbs above and beyond water's normal boiling point. Since this 43 00:02:43,040 --> 00:02:45,760 Speaker 1: water is held in tight corridors, it's got nowhere else 44 00:02:45,760 --> 00:02:49,680 Speaker 1: to go at first, Bearing down on the superheated liquid 45 00:02:49,880 --> 00:02:53,960 Speaker 1: is a combination of overhanging rock and colder water. Add 46 00:02:54,000 --> 00:02:56,240 Speaker 1: cramped quarters to the mix, and you've got a recipe 47 00:02:56,360 --> 00:03:00,160 Speaker 1: for high pressure. But the pressure doesn't last for her. 48 00:03:00,840 --> 00:03:04,400 Speaker 1: In a geyser like Old Faithful, hyperactive steam bubbles eventually 49 00:03:04,480 --> 00:03:07,359 Speaker 1: push a small percentage of the groundwater through a narrow 50 00:03:07,400 --> 00:03:11,160 Speaker 1: opening at the surface. Just like that, the pressure decreases 51 00:03:11,240 --> 00:03:15,320 Speaker 1: and sets off an explosion of hot water and steam. 52 00:03:15,360 --> 00:03:18,120 Speaker 1: If you're wise, you'll give Old Faithful a wide berth. 53 00:03:18,840 --> 00:03:21,600 Speaker 1: Visitors can safely watch the geyser erupt from a boardwalk 54 00:03:21,680 --> 00:03:24,920 Speaker 1: maintained by Yellowstone Venture off that path and you might 55 00:03:25,000 --> 00:03:27,040 Speaker 1: be on the hook for six months in prison and 56 00:03:27,080 --> 00:03:30,720 Speaker 1: a five thousand dollar fine. And besides, getting too close 57 00:03:30,760 --> 00:03:34,360 Speaker 1: to hydrothermal features like geysers or hot springs isn't a 58 00:03:34,440 --> 00:03:38,200 Speaker 1: cool idea. When Old Faithful goes off, the water temperature 59 00:03:38,240 --> 00:03:40,760 Speaker 1: around its vent can hit two hundred and four degrees 60 00:03:40,800 --> 00:03:45,120 Speaker 1: fahrenheit that's ninety six celsius. Meanwhile, the steam gets even hotter, 61 00:03:45,480 --> 00:03:48,560 Speaker 1: sometimes exceeding three hundred and fifty degrees fahrenheit or hundred 62 00:03:48,560 --> 00:03:53,160 Speaker 1: and seventy seven celsius viewed from an appropriate distance, Old 63 00:03:53,160 --> 00:03:57,160 Speaker 1: Faithful's eruptions are thrilling spectacles, even if you've seen one before. 64 00:03:57,400 --> 00:04:00,760 Speaker 1: You might want to revisit the geyser someday. Because certain 65 00:04:00,840 --> 00:04:05,120 Speaker 1: eruptions last longer than others, will explained that Old Faithful 66 00:04:05,280 --> 00:04:08,120 Speaker 1: isn't as predictable as it once seemed. There are two 67 00:04:08,200 --> 00:04:12,200 Speaker 1: different categories of gaps between eruptions and of eruptions themselves. 68 00:04:13,360 --> 00:04:15,560 Speaker 1: An eruption that begins and ends and under two and 69 00:04:15,560 --> 00:04:19,679 Speaker 1: a half minutes is considered short. Others are longer. After 70 00:04:19,800 --> 00:04:22,800 Speaker 1: a short eruption, there will be an intermission of sixty 71 00:04:22,839 --> 00:04:26,400 Speaker 1: two sixty five minutes before the geyser spouts again. Yet 72 00:04:26,520 --> 00:04:29,599 Speaker 1: Old Faithful will reliably take a break of around ninety 73 00:04:29,600 --> 00:04:34,359 Speaker 1: two minutes once a long eruption subsides. Over the past 74 00:04:34,360 --> 00:04:37,599 Speaker 1: fifty years, long eruptions at Old Faithful have become the norm. 75 00:04:38,080 --> 00:04:40,320 Speaker 1: Short ones still occur, but they are rarer than they 76 00:04:40,400 --> 00:04:43,560 Speaker 1: used to be, and no one is entirely sure why. 77 00:04:44,200 --> 00:04:48,000 Speaker 1: While the mystery is unresolved, some geologists blame recent earthquakes 78 00:04:48,040 --> 00:04:52,679 Speaker 1: for this changing schedule. The geyser's source is another riddle. 79 00:04:53,360 --> 00:04:56,480 Speaker 1: Scientists haven't determined where Old Faithful gets its water supply, 80 00:04:57,040 --> 00:05:00,640 Speaker 1: though in a study, Wu and five call leagues revealed 81 00:05:00,680 --> 00:05:04,520 Speaker 1: an important clue. Using seismic wave sensors, they found a 82 00:05:04,600 --> 00:05:08,440 Speaker 1: natural reservoir below the historic Old Faithful Inn, which stands 83 00:05:08,480 --> 00:05:13,160 Speaker 1: southwest of the geyser. Wu said that body is interpreted 84 00:05:13,160 --> 00:05:15,760 Speaker 1: to be a highly fractured and saturated area that we 85 00:05:15,839 --> 00:05:20,120 Speaker 1: think provides fluids as a source to Old Faithful. Plumbing 86 00:05:20,200 --> 00:05:24,360 Speaker 1: questions and bimodal eruptions aside, Old Faithful is indeed more 87 00:05:24,440 --> 00:05:28,360 Speaker 1: Faithful than some of its counterparts. It's time we introduced 88 00:05:28,440 --> 00:05:31,839 Speaker 1: the steamboat geyser, another Yellowstone resident that happens to be 89 00:05:31,880 --> 00:05:35,280 Speaker 1: the world's tallest active geyser, emitting jets of water three 90 00:05:35,400 --> 00:05:38,000 Speaker 1: hundred to four hundred feet into the sky above that's 91 00:05:38,000 --> 00:05:42,840 Speaker 1: about nine and twenty but lu said it is very 92 00:05:42,920 --> 00:05:46,920 Speaker 1: unpredictable and has gone decades between eruptions. The last eruption 93 00:05:47,000 --> 00:05:52,480 Speaker 1: before March was in September. She added, however, that the 94 00:05:53,200 --> 00:05:57,880 Speaker 1: blow up quote began an unprecedented active phase. The Steamboat 95 00:05:57,880 --> 00:06:00,840 Speaker 1: geyser has erupted a total of eighty five times since then, 96 00:06:01,080 --> 00:06:05,720 Speaker 1: with the last eruption occurring February one. We still don't 97 00:06:05,760 --> 00:06:08,520 Speaker 1: know what initiates this act of phase, what controls its 98 00:06:08,600 --> 00:06:13,040 Speaker 1: eruptive behavior, and what the geometry looks like, so keep 99 00:06:13,040 --> 00:06:16,120 Speaker 1: an eye on the headlines. Perhaps we'll see some heated 100 00:06:16,279 --> 00:06:24,320 Speaker 1: arguments about these topics in the near future. Today's episode 101 00:06:24,320 --> 00:06:26,640 Speaker 1: was written by Mark Bancini and produced by Tyler Clang. 102 00:06:27,000 --> 00:06:28,880 Speaker 1: For more on this and lots of other active topics, 103 00:06:28,920 --> 00:06:31,760 Speaker 1: visit how stuff works dot com. Brain Stuff is production 104 00:06:31,760 --> 00:06:34,240 Speaker 1: of I Heart Radio. For more podcasts to my heart Radio, 105 00:06:34,400 --> 00:06:37,080 Speaker 1: visit the iHeart Radio app, Apple Podcasts, or wherever you 106 00:06:37,080 --> 00:06:38,240 Speaker 1: listen to your favorite shows.