WEBVTT - Is Old Faithful Becoming Less Faithful? 0:00:01.920 --> 0:00:06.480 Welcome to brain Stuff, a production of iHeart Radio, Hey 0:00:06.519 --> 0:00:10.240 brain Stuff Lauren bogebam Here. Old Faithful used to have 0:00:10.440 --> 0:00:15.280 a less than modest nickname Eternity's time Piece. Since at 0:00:15.360 --> 0:00:18.640 least the late eighteen hundreds, this wyoming cone geyser has 0:00:18.640 --> 0:00:22.200 wowed spectators with its predictable eruptions. You can see the 0:00:22.239 --> 0:00:25.200 landmark for yourself in Yellowstone National Park, home to over 0:00:25.239 --> 0:00:28.400 five hundred geysers. More than one hundred and fifty of 0:00:28.400 --> 0:00:32.280 these water spurting marvels, including Old Faithful, occupy the park's 0:00:32.360 --> 0:00:36.920 upper geyser basin. So named in eighteen seventy because it's 0:00:36.920 --> 0:00:40.720 spouted at regular intervals, Old Faithful gets more fanfair than 0:00:40.760 --> 0:00:44.880 any other geothermal attraction in the world. Visited by presidents 0:00:44.880 --> 0:00:49.000 and immortalized by artists, the geyser spouts about seventeen times 0:00:49.000 --> 0:00:52.760 a day. Countdown clocks tell gathering tourists when too ready 0:00:52.800 --> 0:00:56.480 their cameras for the next waterworks show. You see. There's 0:00:56.520 --> 0:00:59.560 a simple formula rangers used to estimate how much time 0:00:59.560 --> 0:01:02.880 will likely elapse between any two eruptions of Old Faithful. 0:01:03.800 --> 0:01:07.240 According to the National Park Service, about of these eruption 0:01:07.319 --> 0:01:10.160 predictions are accurate within a window of plus or minus 0:01:10.200 --> 0:01:14.440 ten minutes. That's a solid track record, but Old Faithful 0:01:14.560 --> 0:01:17.240 still isn't something you'd want to set your watch by. 0:01:17.560 --> 0:01:21.080 Five decades of observation have revealed that the geyser is changing. 0:01:22.319 --> 0:01:26.800 Since nine, the average interval between Old Faithful's eruptions has 0:01:26.880 --> 0:01:30.000 gotten longer, and while most of the actual eruptions which 0:01:30.000 --> 0:01:33.080 occurred back then were rather brief, this is no longer 0:01:33.120 --> 0:01:37.440 the case. But we spoke via email with Sin May Wu, 0:01:37.520 --> 0:01:39.960 a geologist at the University of Utah who studied the 0:01:39.959 --> 0:01:44.040 physics of geyser's and related structures. She said geysers are 0:01:44.120 --> 0:01:48.200 rare because they require very unique geologic conditions, a persistent 0:01:48.240 --> 0:01:51.800 heat source, abundant water supply from groundwater systems, and a 0:01:51.880 --> 0:01:55.040 porous or fractured medium that allows fluid migration and heat 0:01:55.080 --> 0:02:00.360 transfer within. Usually the heat comes from magma, a liquid 0:02:00.440 --> 0:02:03.120 or semi liquid rock found below Earth's crust, which is 0:02:03.160 --> 0:02:06.920 called lava once it bursts onto the surface. Yellow Stone 0:02:07.000 --> 0:02:10.760 is positioned over two magma chambers, including a nice long 0:02:10.840 --> 0:02:13.760 one that's just three to ten miles underground that's five 0:02:13.800 --> 0:02:17.880 to seventeen kilometers. Their maker was a localized swell of 0:02:17.919 --> 0:02:22.480 abnormally hot material beneath the crust, classified as a mantle plume. 0:02:22.720 --> 0:02:26.080 It's the reason why Yellowstone has the world's largest geyser collection. 0:02:27.080 --> 0:02:31.799 The chambers warm up subterranean reservoirs of liquid groundwater. Although 0:02:31.840 --> 0:02:34.720 the physics here aren't entirely settled, we do know that 0:02:34.760 --> 0:02:38.560 some of this water gets superheated. That means it's temperature 0:02:38.600 --> 0:02:42.960 climbs above and beyond water's normal boiling point. Since this 0:02:43.040 --> 0:02:45.760 water is held in tight corridors, it's got nowhere else 0:02:45.760 --> 0:02:49.680 to go at first, Bearing down on the superheated liquid 0:02:49.880 --> 0:02:53.960 is a combination of overhanging rock and colder water. Add 0:02:54.000 --> 0:02:56.240 cramped quarters to the mix, and you've got a recipe 0:02:56.360 --> 0:03:00.160 for high pressure. But the pressure doesn't last for her. 0:03:00.840 --> 0:03:04.400 In a geyser like Old Faithful, hyperactive steam bubbles eventually 0:03:04.480 --> 0:03:07.359 push a small percentage of the groundwater through a narrow 0:03:07.400 --> 0:03:11.160 opening at the surface. Just like that, the pressure decreases 0:03:11.240 --> 0:03:15.320 and sets off an explosion of hot water and steam. 0:03:15.360 --> 0:03:18.120 If you're wise, you'll give Old Faithful a wide berth. 0:03:18.840 --> 0:03:21.600 Visitors can safely watch the geyser erupt from a boardwalk 0:03:21.680 --> 0:03:24.920 maintained by Yellowstone Venture off that path and you might 0:03:25.000 --> 0:03:27.040 be on the hook for six months in prison and 0:03:27.080 --> 0:03:30.720 a five thousand dollar fine. And besides, getting too close 0:03:30.760 --> 0:03:34.360 to hydrothermal features like geysers or hot springs isn't a 0:03:34.440 --> 0:03:38.200 cool idea. When Old Faithful goes off, the water temperature 0:03:38.240 --> 0:03:40.760 around its vent can hit two hundred and four degrees 0:03:40.800 --> 0:03:45.120 fahrenheit that's ninety six celsius. Meanwhile, the steam gets even hotter, 0:03:45.480 --> 0:03:48.560 sometimes exceeding three hundred and fifty degrees fahrenheit or hundred 0:03:48.560 --> 0:03:53.160 and seventy seven celsius viewed from an appropriate distance, Old 0:03:53.160 --> 0:03:57.160 Faithful's eruptions are thrilling spectacles, even if you've seen one before. 0:03:57.400 --> 0:04:00.760 You might want to revisit the geyser someday. Because certain 0:04:00.840 --> 0:04:05.120 eruptions last longer than others, will explained that Old Faithful 0:04:05.280 --> 0:04:08.120 isn't as predictable as it once seemed. There are two 0:04:08.200 --> 0:04:12.200 different categories of gaps between eruptions and of eruptions themselves. 0:04:13.360 --> 0:04:15.560 An eruption that begins and ends and under two and 0:04:15.560 --> 0:04:19.679 a half minutes is considered short. Others are longer. After 0:04:19.800 --> 0:04:22.800 a short eruption, there will be an intermission of sixty 0:04:22.839 --> 0:04:26.400 two sixty five minutes before the geyser spouts again. Yet 0:04:26.520 --> 0:04:29.599 Old Faithful will reliably take a break of around ninety 0:04:29.600 --> 0:04:34.359 two minutes once a long eruption subsides. Over the past 0:04:34.360 --> 0:04:37.599 fifty years, long eruptions at Old Faithful have become the norm. 0:04:38.080 --> 0:04:40.320 Short ones still occur, but they are rarer than they 0:04:40.400 --> 0:04:43.560 used to be, and no one is entirely sure why. 0:04:44.200 --> 0:04:48.000 While the mystery is unresolved, some geologists blame recent earthquakes 0:04:48.040 --> 0:04:52.679 for this changing schedule. The geyser's source is another riddle. 0:04:53.360 --> 0:04:56.480 Scientists haven't determined where Old Faithful gets its water supply, 0:04:57.040 --> 0:05:00.640 though in a study, Wu and five call leagues revealed 0:05:00.680 --> 0:05:04.520 an important clue. Using seismic wave sensors, they found a 0:05:04.600 --> 0:05:08.440 natural reservoir below the historic Old Faithful Inn, which stands 0:05:08.480 --> 0:05:13.160 southwest of the geyser. Wu said that body is interpreted 0:05:13.160 --> 0:05:15.760 to be a highly fractured and saturated area that we 0:05:15.839 --> 0:05:20.120 think provides fluids as a source to Old Faithful. Plumbing 0:05:20.200 --> 0:05:24.360 questions and bimodal eruptions aside, Old Faithful is indeed more 0:05:24.440 --> 0:05:28.360 Faithful than some of its counterparts. It's time we introduced 0:05:28.440 --> 0:05:31.839 the steamboat geyser, another Yellowstone resident that happens to be 0:05:31.880 --> 0:05:35.280 the world's tallest active geyser, emitting jets of water three 0:05:35.400 --> 0:05:38.000 hundred to four hundred feet into the sky above that's 0:05:38.000 --> 0:05:42.840 about nine and twenty but lu said it is very 0:05:42.920 --> 0:05:46.920 unpredictable and has gone decades between eruptions. The last eruption 0:05:47.000 --> 0:05:52.480 before March was in September. She added, however, that the 0:05:53.200 --> 0:05:57.880 blow up quote began an unprecedented active phase. The Steamboat 0:05:57.880 --> 0:06:00.840 geyser has erupted a total of eighty five times since then, 0:06:01.080 --> 0:06:05.720 with the last eruption occurring February one. We still don't 0:06:05.760 --> 0:06:08.520 know what initiates this act of phase, what controls its 0:06:08.600 --> 0:06:13.040 eruptive behavior, and what the geometry looks like, so keep 0:06:13.040 --> 0:06:16.120 an eye on the headlines. Perhaps we'll see some heated 0:06:16.279 --> 0:06:24.320 arguments about these topics in the near future. Today's episode 0:06:24.320 --> 0:06:26.640 was written by Mark Bancini and produced by Tyler Clang. 0:06:27.000 --> 0:06:28.880 For more on this and lots of other active topics, 0:06:28.920 --> 0:06:31.760 visit how stuff works dot com. Brain Stuff is production 0:06:31.760 --> 0:06:34.240 of I Heart Radio. For more podcasts to my heart Radio, 0:06:34.400 --> 0:06:37.080 visit the iHeart Radio app, Apple Podcasts, or wherever you 0:06:37.080 --> 0:06:38.240 listen to your favorite shows.