Latest / PlanetGeo: The Geology Podcast / Volcanoes Revisited: Part 2 - Dr. Andrew Calvert ReRelease

Transcript

Volcanoes Revisited: Part 2 - Dr. Andrew Calvert ReRelease · PlanetGeo: The Geology Podcast

• 0:02
  SPEAKER_03: Welcome to Planet Geo, the podcast where we talk about our amazing planet, how it works, and why it matters to you.
• 0:14
  SPEAKER_03: Hey Dan, what's going on today?
• 0:16
  SPEAKER_03: Hey Christopher, what's up, man?
• 0:18
  SPEAKER_03: Why are you laughing at me, I just think I don't know.
• 0:24
  SPEAKER_02: Alright, I need more respect.
• 0:25
  SPEAKER_02: Okay.
• 0:26
  SPEAKER_02: Can we just lay that down?
• 0:28
  SPEAKER_02: I need a little bit more respect.
• 0:30
  SPEAKER_03: I mean, I d I do respect you.
• 0:31
  SPEAKER_03: I respect you.
• 0:32
  SPEAKER_03: You know this, Chris.
• 0:33
  SPEAKER_03: I respect the hell out of you.
• 0:34
  SPEAKER_03: But I don't necessarily need to respect the way you look on Zoom all the time, do I?
• 0:39
  SPEAKER_02: Why?
• 0:40
  SPEAKER_02: Oh, wait a minute.
• 0:41
  SPEAKER_02: Hold on.
• 0:42
  SPEAKER_03: Yeah, there we go.
• 0:45
  SPEAKER_03: I didn't even realize it's like, you know, when somebody opens up their laptop and the laptop's only partially open so they can see the screen, but you're like looking at like the bottom half of their mouth and then their double chin and then they're like And only old people do that, right?
• 1:00
  SPEAKER_02: Exactly.
• 1:00
  SPEAKER_02: So I just looked at it up like, wait a minute, what am I doing that's oh funny?
• 1:05
  SPEAKER_02: And it's pointed at my chin.
• 1:07
  SPEAKER_03: You look worthy of respect now, Chris.
• 1:09
  SPEAKER_03: All right, here we go.
• 1:10
  SPEAKER_02: Thank you.
• 1:10
  SPEAKER_02: I appreciate that.
• 1:11
  SPEAKER_02: All right, hey, Jesse, Dr.
• 1:13
  SPEAKER_02: Remink, what are we doing?
• 1:15
  SPEAKER_03: We are part two of our volcanology re-release.
• 1:17
  SPEAKER_03: We are re-releasing an episode, an interview really, that we did with Dr.
• 1:21
  SPEAKER_03: Andy Culvert, which, man, this was a really cool interview.
• 1:24
  SPEAKER_03: He is the scientist in charge of the California Volcano Observatory, also known as Calvo.
• 1:29
  SPEAKER_03: And so he leads about 35 geologists, geophysicists, and hydrologists that study volcanoes specifically in California, right, Chris?
• 1:37
  SPEAKER_03: And these are volcanoes you are very familiar with.
• 1:40
  SPEAKER_03: You've climbed a lot of them and hiked around the others.
• 1:43
  SPEAKER_02: Yeah, I found this interview to be one of the best that we've ever done.
• 1:46
  SPEAKER_02: And that is a high bar.
• 1:48
  SPEAKER_02: Andy and I are kindred spirits, I think, anyway.
• 1:51
  SPEAKER_03: Yeah, you totally are.
• 1:52
  SPEAKER_03: You both got into geology because of Mount St.
• 1:54
  SPEAKER_03: Helens.
• 1:55
  SPEAKER_03: Like yeah, it was you guys really were kind of vibing together in this interview.
• 1:59
  SPEAKER_02: We did, but actually, so you know, I don't know, a couple months after the interview that we did, Jenny and I were actually on our way out to California to go um to Yosemite and climb Mount Shasta, which is you know Andy's thing, right?
• 2:12
  SPEAKER_02: That's what he's spent so much time doing and published a lot of papers on.
• 2:16
  SPEAKER_02: And so we uh we got together in San Francisco with Andy and his wife and I.
• 2:22
  SPEAKER_02: Yeah, totally.
• 2:24
  SPEAKER_02: And it lived up.
• 2:25
  SPEAKER_02: Um, it it didn't disappoint.
• 2:27
  SPEAKER_02: He is we're like-minded in a lot of different ways.
• 2:30
  SPEAKER_02: And he hooked us up with one of the climbing rangers there, and it just uh very cool experience.
• 2:36
  SPEAKER_03: Yeah, totally cool.
• 2:37
  SPEAKER_03: That's awesome.
• 2:38
  SPEAKER_03: What a guy.
• 2:38
  SPEAKER_03: Also, what an interesting interview.
• 2:40
  SPEAKER_03: Talks about a lot of really cool stuff, and it talks about how the volcano disaster assistance program kind of actually works and and gave a lot of insight into how these government-funded volcanology research centers and and research observation posts actually work, and it was really, really interesting to hear.
• 2:57
  SPEAKER_03: So, this is part two of four.
• 2:59
  SPEAKER_03: We are on a break, and uh, we'll come back in uh a couple weeks here with some new content.
• 3:04
  SPEAKER_03: But right now, this is an interview with Dr.
• 3:07
  SPEAKER_03: Andrew Culvert coming at you.
• 3:09
  SPEAKER_03: Before we get to it, check out Camp Geo, the first link in the bottom of the page.
• 3:13
  SPEAKER_03: You can follow us on all the social medias at Planet GeoCast.
• 3:16
  SPEAKER_03: Send us an email, planetgeocast at gmail.com, and you can go to our website, planetgeocast.com.
• 3:21
  SPEAKER_03: There you can learn about us, listen to old episodes.
• 3:24
  SPEAKER_03: We got some sort of pseudo blog posts.
• 3:26
  SPEAKER_03: There's transcripts are there, so you can read through that and you can support us there as well.
• 3:30
  SPEAKER_03: So hit that up and uh let us know what you think.
• 3:33
  SPEAKER_03: Sit back, enjoy.
• 3:34
  SPEAKER_03: Cheers.
• 3:39
  SPEAKER_03: Dr.
• 3:39
  SPEAKER_03: Calvert, welcome to Planet Geo, and uh thanks for joining us.
• 3:43
  SPEAKER_03: We're really happy to have you here.
• 3:44
  SPEAKER_01: Thanks.
• 3:45
  SPEAKER_01: I'm excited to be here.
• 3:46
  SPEAKER_01: This is this is great.
• 3:47
  SPEAKER_01: I've listened to a few of your podcasts, and and uh boy, it's fantastic.
• 3:51
  SPEAKER_01: I really, really appreciate your efforts.
• 3:53
  SPEAKER_03: Oh well, we we really appreciate that.
• 3:55
  SPEAKER_03: We appreciate you giving us the time.
• 3:56
  SPEAKER_03: So, you know, we have a a ton of I mean, a ton of questions.
• 4:00
  SPEAKER_03: Uh, this is gonna be a super exciting and interesting conversation, but we kind of like to always kind of start out with what got you into geoscience?
• 4:07
  SPEAKER_03: Was there sort of this aha moment at any point?
• 4:10
  SPEAKER_03: Or how how'd you make your path into you know your current position?
• 4:14
  SPEAKER_01: Yeah, my my aha moment really came in college, um, but the seeds really got planted a lot earlier.
• 4:20
  SPEAKER_01: Um, I grew up in northern Idaho and it's on the Columbia River Basalts and the Palouse, which are these sort of dirt dunes on top of it.
• 4:30
  SPEAKER_01: And and I always kind of grew up thinking rocks were really ugly.
• 4:34
  SPEAKER_01: They're just these brown, scummy.
• 4:36
  SPEAKER_01: Oh, man.
• 4:37
  SPEAKER_01: And then we'd go camping in these beautiful places, like in the Belt Rocks up in um northern Idaho, and then in Montana, we'd go to Vancouver Island, and and man, out there the rocks were beautiful.
• 4:49
  SPEAKER_01: You know, they'd they'd be shiny, they'd flash at you.
• 4:52
  SPEAKER_01: And and I I remember seeing that and and thinking, huh, that's really interesting.
• 4:57
  SPEAKER_01: And so we were just out there and you know, kind of just interested in the earth, um, curious about the earth.
• 5:04
  SPEAKER_01: One of the things that happened regularly, we'd we'd go over and visit family in the Willamette Valley in Oregon, as we drive down the Columbia River Gorge.
• 5:13
  SPEAKER_01: And there you're driving through these Columbia River basalts.
• 5:16
  SPEAKER_01: It's very dramatic topography and really, really interesting.
• 5:20
  SPEAKER_01: And and on a clear day, you'd look to the north and you'd see, well, you know, on the way, you'd see several volcanoes, but one in particular, there was this conical volcano Mount St.
• 5:29
  SPEAKER_01: Helens.
• 5:30
  SPEAKER_01: It's that's up north of Portland.
• 5:32
  SPEAKER_01: And I remember several times seeing it just beautiful snow covered, it was the Mount Fuji of the Cascades.
• 5:40
  SPEAKER_01: And and um then uh in spring of 1980, I uh I was in seventh grade, and there was um an earthquake at Mount St.
• 5:52
  SPEAKER_01: Helens, uh, and then a bunch of other earthquakes, and then a lot of deformation on the north side.
• 5:57
  SPEAKER_01: And and we were really interested.
• 6:00
  SPEAKER_01: The newspapers covered it really well, and and we we talked about it in school.
• 6:04
  SPEAKER_01: I was actually in an earth science class in in seventh grade, it was a geology class, and we talked about it there, and it was pretty cool, you know, just to have something deforming.
• 6:16
  SPEAKER_01: And that was sort of when when I realized that the earth wasn't static and and that it was it could be dynamic.
• 6:23
  SPEAKER_01: And um, you know, continued on for a couple of months, so from March, April, and into May.
• 6:30
  SPEAKER_01: And then on um May 18th, 1980.
• 6:33
  SPEAKER_03: So this was in a time before Twitter and all this kind of stuff.
• 6:35
  SPEAKER_03: No kidding.
• 6:36
  SPEAKER_03: You were getting alerts on your cell phone.
• 6:38
  SPEAKER_01: No, I didn't have, yeah, we didn't have phones, we didn't have, we didn't have anything.
• 6:42
  SPEAKER_01: And and and so seeing this come across, and then it it blocked out the sun, and it just started getting dark.
• 6:48
  SPEAKER_01: And and by the time we got home, it was darker than the darkest night.
• 6:53
  SPEAKER_01: And I remember my mom had this green cardigan sweater on, and she went across and checked on our neighbor and came back, and and she got back in, she said, huh?
• 7:03
  SPEAKER_01: And there are these little gray flecks on her on her sweater.
• 7:07
  SPEAKER_01: You know, it was incredible.
• 7:08
  SPEAKER_01: It was really, really interesting.
• 7:10
  SPEAKER_01: We'd look out, you could see the ash coming down and and landing on the street.
• 7:16
  SPEAKER_01: And they came on the the radio and they they said, Well, you know, there's not gonna be any school tomorrow.
• 7:22
  SPEAKER_01: No school tomorrow.
• 7:23
  SPEAKER_01: School's canceled.
• 7:25
  SPEAKER_01: Yes, celebrate.
• 7:27
  SPEAKER_01: It was a big deal to get out of day of school, right?
• 7:29
  SPEAKER_01: We had we'd had snow days.
• 7:31
  SPEAKER_01: We we had a bear day once.
• 7:33
  SPEAKER_01: There was a bear in the neighborhood.
• 7:34
  SPEAKER_01: That's awesome too.
• 7:35
  SPEAKER_01: And yeah, just but but to have a volcano day.
• 7:39
  SPEAKER_01: Yeah, volcano day, that's great.
• 7:41
  SPEAKER_01: It's pretty cool, pretty cool.
• 7:43
  SPEAKER_01: So so next day we get up, and you know, we had about a half an inch of ash, and it was like a white snowfall.
• 7:50
  SPEAKER_01: It was a calm, beautiful day again, and we didn't go outside because we were told it wasn't really safe.
• 7:56
  SPEAKER_01: And somehow we got a hold of some N95 masks or the equivalent of N95 masks.
• 8:02
  SPEAKER_01: And and I still remember, you know, when we start, we wear these masks all the time, and every time I put one on, it has the same smell.
• 8:08
  SPEAKER_01: It has that that kind of manufacturing solvent smell of a mask.
• 8:15
  SPEAKER_01: I remember that vividly from from that time.
• 8:18
  SPEAKER_01: That afternoon they came on the radio and they said no school for the rest of the year.
• 8:23
  SPEAKER_01: Oh wow, it was pretty shocking, but yeah, I got cheated out of seventh, you know, three weeks of seventh grade.
• 8:30
  SPEAKER_02: I've I've been cheated.
• 8:32
  SPEAKER_02: I don't know about that.
• 8:33
  SPEAKER_02: I've been paying the earth back, paying the earth back ever since.
• 8:36
  SPEAKER_03: Yeah, not great.
• 8:38
  SPEAKER_03: Well, I mean, you must associate volcanoes with like fun times, you know, based on this experience.
• 8:43
  SPEAKER_03: That's that's a really that's a great story, yeah.
• 8:45
  SPEAKER_01: And then kind of the to the aha moment, I I didn't really know about geology then until college.
• 8:52
  SPEAKER_01: And and I I went in kind of thinking pre-med, you know, so I don't know what I'm gonna do.
• 8:56
  SPEAKER_01: And and my friend told me, uh, she took a geology class.
• 9:00
  SPEAKER_01: She gotta take this class, it's greatest thing ever.
• 9:02
  SPEAKER_01: So it was at eight o'clock in the morning.
• 9:05
  SPEAKER_01: Um, it was winter quarter, and I uh I thought, uh, all right, I took it.
• 9:11
  SPEAKER_01: And it was like falling in love.
• 9:13
  SPEAKER_01: It was uh taught by a guy named Dennis Byrd.
• 9:15
  SPEAKER_01: This is at Stanford.
• 9:17
  SPEAKER_03: I know Dennis Byrd, really dynamic guy.
• 9:20
  SPEAKER_01: Really fantastic, and it was the first undergrad class he ever taught, and he just poured his heart into it.
• 9:28
  SPEAKER_01: And you know, he told us stories about and has showed slides from from Greenland, field work in Greenland and and in uh Antarctica and and all over the place, and and just told these great stories.
• 9:40
  SPEAKER_01: And it was it was it really was like falling in love.
• 9:43
  SPEAKER_01: I I was at every eight o'clock lecture, and and it was great.
• 9:47
  SPEAKER_02: And so you were sold right there, huh?
• 9:49
  SPEAKER_01: I was sold, but you know, I thought, you know, is this just a great class?
• 9:54
  SPEAKER_01: And so I I open up the courses for the next quarter and and I look and see what the next class is, and it's geology 80, and it's called rocks and minerals.
• 10:04
  SPEAKER_01: Well, now that is the most boring class I can imagine.
• 10:07
  SPEAKER_01: Rocks and minerals.
• 10:08
  SPEAKER_01: If that's good, I'll be a geology major.
• 10:10
  SPEAKER_01: And it was taught by this guy, Bob Coleman, who was a famous USGS geologist, worked all over the world.
• 10:16
  SPEAKER_01: It was it was an incredible class, too, also at eight o'clock, all about plate tectonics, and and just taught me how to look at a rock.
• 10:24
  SPEAKER_01: And and the the labs were out on the out on the lawn, and you you just use the sun and your hand lands, and he would say, visit the surface of the rock, and and you just look at the textures and and and kind of learn how rocks tell a story that you can use um to understand the earth.
• 10:45
  SPEAKER_03: I mean, is that how you do labs at Stanford?
• 10:47
  SPEAKER_03: Is just go out in the sun and look at the rocks?
• 10:50
  SPEAKER_03: I mean, that sounds that's every everything's easy at Stanford.
• 10:55
  SPEAKER_03: Oh, that's awesome.
• 10:56
  SPEAKER_03: Well, you're you're destined to be a volcanologist then.
• 10:59
  SPEAKER_02: Yeah, so yeah, Andy, let's pivot then to to this.
• 11:02
  SPEAKER_02: You are the scientist in charge of the California Volcano Observatory, otherwise known as Calvo.
• 11:08
  SPEAKER_02: Um, what does Calvo do specifically?
• 11:12
  SPEAKER_01: Yeah, so we're responsible for for studying and monitoring the California and Nevada volcanoes, and and that involves um communicating the hazard and potentially responding to an eruption.
• 11:27
  SPEAKER_01: So if there's an eruption at say Lassen Peak, I'm on the hook to run the response for for that eruption.
• 11:36
  SPEAKER_01: And there are about 35 of us here employees, uh, plus another dozen retired folks, Samaritai, that that work just as hard as the paid people.
• 11:47
  SPEAKER_01: And um we're we're part of a larger group, the Volcano Science Center.
• 11:53
  SPEAKER_01: So it's a it's a division of the U.S.
• 11:56
  SPEAKER_01: Geological Survey that focuses on volcanoes.
• 11:59
  SPEAKER_03: So this is all federally funded institutes?
• 12:01
  SPEAKER_01: Yep, so I'm working I'm working for you, and uh, and our mission is to really protect the US from volcanic eruptions.
• 12:09
  SPEAKER_01: Wow, no pressure.
• 12:10
  SPEAKER_01: Yeah, wow.
• 12:14
  SPEAKER_01: Uh there are five observatories.
• 12:16
  SPEAKER_01: Uh there's the Alaska Volcano Observatory centered in Anchorage, Hawaii Volcano Observatory centered at Gila, Hawaii, uh, Cascades Observatory in Vancouver, Washington.
• 12:28
  SPEAKER_01: The Yellowstone Volcano Observatory is also centered at CBO at the Cascades Volcano Observatory.
• 12:35
  SPEAKER_01: So it's it's a smaller group that works out there.
• 12:37
  SPEAKER_01: And then there's us, Calibo.
• 12:39
  SPEAKER_01: And uh we so we're yeah, responsible for California and Nevada volcanoes.
• 12:45
  SPEAKER_01: We also have a group um called VDAP, it's the volcano disaster assistance program, and and they're State Department funded, but they're they work, they're also at CBO in Vancouver, and they work all over the world.
• 12:59
  SPEAKER_01: They're designed to kind of help developing countries manage and respond to volcanic eruptions.
• 13:06
  SPEAKER_01: So we we you know most of our work is domestic, but um feed app works uh overseas, and um you know you can think of observatory as um you can take a medical analogy that you you go into the ER and they what's the first thing they do, they take your pulse and your temperature, they they take your your vital signs, and we do that.
• 13:31
  SPEAKER_01: That's the sort of monitoring aspects where we're looking at the volcano uh from satellites to try to see if it's deforming.
• 13:39
  SPEAKER_01: We're listening, we have seismometers, seismic arrays around volcanoes.
• 13:44
  SPEAKER_01: When magma is moving through up to the surface, it breaks a lot of rock and that causes a little earthquakes.
• 13:51
  SPEAKER_01: By GPS, we measure the deformation and then we monitor their gases.
• 13:55
  SPEAKER_01: There are a couple of continuous stations, but usually that's a kind of a survey mode in the summertime.
• 14:00
  SPEAKER_01: You go out and you take a gas sample from uh summit of Mount Shasta and bring it back and look and see if it's the same as previous years or it's somehow different.
• 14:10
  SPEAKER_02: Okay, so you have uh are you constantly monitoring these volcanoes then with seismometers and so on?
• 14:16
  SPEAKER_02: Is that yes?
• 14:18
  SPEAKER_01: Yes.
• 14:18
  SPEAKER_01: And so and and we, yeah, so we're we're we have a duty scientist uh rotation in our office.
• 14:24
  SPEAKER_01: There are six people that take a week at a time, and and uh you know, my phone will ding if there's an earthquake somewhere, and we watch the seismic records.
• 14:33
  SPEAKER_01: That's our principal tool, really, is the seismicity for kind of listening to see whether it's coming.
• 14:40
  SPEAKER_01: So that's the the real kind of monitoring aspect.
• 14:43
  SPEAKER_01: But then we also have the you know, the next question they ask you is what's your family history?
• 14:47
  SPEAKER_01: You know, have you been sick before?
• 14:49
  SPEAKER_01: What did your parents die of, or something?
• 14:52
  SPEAKER_01: And you want to understand the history, and and that's the eruptive history of each volcano.
• 14:57
  SPEAKER_01: And that's actually what I do.
• 14:58
  SPEAKER_01: So I go out and I make a geologic map.
• 15:02
  SPEAKER_01: So you map out the old deposits that have come out of a particular volcano, and you figure out the composition, how explosive it was, when it happened.
• 15:14
  SPEAKER_01: That's something I work on a lot, is the timing.
• 15:17
  SPEAKER_01: And you sort of develop a personality profile for each volcano.
• 15:21
  SPEAKER_01: You see whether it's a it's a bad player, it's some it's it's one that erupts constantly, or it can sit for five or ten thousand years.
• 15:29
  SPEAKER_03: I really like that analogy.
• 15:30
  SPEAKER_03: That's a good medical analogy.
• 15:31
  SPEAKER_03: That's a great one.
• 15:32
  SPEAKER_03: Yeah.
• 15:32
  SPEAKER_02: So, Andy, that ties into my next question, which I thought of it today.
• 15:36
  SPEAKER_02: So um, really quickly, what are some of the other notable volcanoes in California?
• 15:41
  SPEAKER_02: We're going to talk about Shasta a little bit later, and I love Mount Shasta.
• 15:45
  SPEAKER_02: So, what are some of the other notable volcanoes?
• 15:47
  SPEAKER_01: Yeah, so we have six that we really keep track of.
• 15:50
  SPEAKER_01: The largest uh and what we worry about the most really uh, well, Mount Shasta we we worry about a lot, but there's Long Valley Caldera.
• 15:59
  SPEAKER_01: So a caldera is a depressed area in the middle of a volcanic system, and it's depressed because there was such a big eruption, so much material came out of that hole that the roof collapsed.
• 16:11
  SPEAKER_01: And so things like Crater Lake is a perfect example, or uh Yellowstone.
• 16:17
  SPEAKER_01: And and Long Valley Caldera is a is a large caldera, had a huge eruption 750,000 years ago.
• 16:25
  SPEAKER_01: And since then there have been eruptions, so we we keep a good eye on Long Valley Caldera, and then it's neighbor to the north, sort of into Mono Lake, there are some these Mono craters.
• 16:36
  SPEAKER_01: So that's one of our one of the ones we watch.
• 16:39
  SPEAKER_01: Then there are a couple of cascade volcanoes, so there's Lassen Peak and Shasta and Medicine Lake.
• 16:47
  SPEAKER_01: So three of them that are in northernmost California.
• 16:51
  SPEAKER_01: Those are Cascade Arc strata volcanoes, and if you want me to describe that, I can I can in a minute.
• 16:57
  SPEAKER_01: Uh then another one is uh the Clear Lake volcanic field.
• 17:01
  SPEAKER_01: It's just north of San Francisco.
• 17:03
  SPEAKER_01: There's a lake with a a number of uh domes and mars, which are subaqueous eruptions, and uh it's a it's a place that hasn't erupted for quite a while, but we're actually restarting some some studies there.
• 17:17
  SPEAKER_01: And then there are two other fields that are down south.
• 17:21
  SPEAKER_01: So so one right down near the Mexican border, Salton Buttes, right on the San Andreas Fault, uh, at the very beginning of the San Andreas Fault, and those erupted a couple thousand years ago, and then another set of domes called Koso, and that's on a naval uh reservation in eastern California.
• 17:39
  SPEAKER_02: Andy, what's the mechanism for those volcanoes to the south?
• 17:43
  SPEAKER_02: Um you said you have the Cascadia ones, but what's the mechanism for the ones in central and southern California?
• 17:50
  SPEAKER_01: Yeah, so I mean there are a few different ways to make volcanoes.
• 17:53
  SPEAKER_01: And one way is to take hot rocks and move them closer to the surface.
• 17:59
  SPEAKER_01: And as they move closer to the surface, they turn from a solid to a little bit liquid and they can erupt.
• 18:06
  SPEAKER_01: And we have those sorts of volcanoes along the mid-ocean ridges, say out in the middle of the Atlantic Ocean or in the Pacific.
• 18:14
  SPEAKER_01: There are also some in Basin and Range Province, which is the area of the west that is is spreading.
• 18:21
  SPEAKER_01: The you know the distance between Reno, Nevada and Salt Lake City has doubled in the last 20 million years.
• 18:29
  SPEAKER_01: It's twice as far.
• 18:31
  SPEAKER_01: And as you spread things out, you can imagine the crust thinning.
• 18:35
  SPEAKER_01: You can imagine hot rocks getting closer to the surface.
• 18:38
  SPEAKER_01: So that's one way to make a volcano is you move hot rocks closer to the surface.
• 18:42
  SPEAKER_01: And that's what we have at Long Valley in Eastern California.
• 18:46
  SPEAKER_01: You're you're right on the edge of the Sierra Nevada, and you're on one of these extensional faults, and you're moving hot rocks up close to the surface.
• 18:54
  SPEAKER_01: So those are extensional regime sorts of volcanoes.
• 18:57
  SPEAKER_01: That's that's sort of what you have at the Salton Buttes down by the Mexican border, too.
• 19:02
  SPEAKER_03: So, Andy, there there's been uh a couple of fairly prolific, at least in the media and like on you know, science Twitter and stuff like this, things that are prolific.
• 19:10
  SPEAKER_03: A couple recent volcanic eruptions on Iceland and uh at La Sufriere in the Antilles.
• 19:15
  SPEAKER_03: I think I pronounced that right.
• 19:16
  SPEAKER_03: Uh correct me if I'm wrong though.
• 19:18
  SPEAKER_01: Yeah, your French is about as good as mine, it sounds like yes, which means it's horrible, Jesse.
• 19:25
  SPEAKER_02: Exactly.
• 19:26
  SPEAKER_03: Terrible, terrible French.
• 19:27
  SPEAKER_03: So can you give us like a short, you know, elevator pitch to why volcanologists are excited about these two eruptions?
• 19:36
  SPEAKER_01: A lot of it is that they're really accessible, you know, they're in places that people live.
• 19:42
  SPEAKER_01: So there are societal effects.
• 19:44
  SPEAKER_01: If you're if you look at La Sufriere, it's those are explosive eruptions happening on an island that has tens of thousands of people on it.
• 19:52
  SPEAKER_01: And so it matters to those people.
• 19:54
  SPEAKER_01: And so we really want to want to figure out how to keep them safe.
• 19:58
  SPEAKER_01: And and those sorts of eruptions happen a lot, especially in the developing world, say down in Indonesia.
• 20:05
  SPEAKER_01: They're they're pretty common, but when they happen in somewhat more developed places, we hear about them a little bit more.
• 20:12
  SPEAKER_03: Okay.
• 20:12
  SPEAKER_01: You know, the La Sufrière just had a start, uh, it's an instrumented volcano.
• 20:18
  SPEAKER_03: And meaning, what does that mean as far as there are instruments like constantly monitoring the volcano?
• 20:23
  SPEAKER_03: Is that what that means?
• 20:24
  SPEAKER_01: Yeah, I actually don't know if that's true, but I think there there were seismometers that were installed from the beginning, and there certainly are seismometers that have been installed since there was some activity.
• 20:35
  SPEAKER_01: And there are a lot of people there, there are a lot of people that live on the flanks of that volcano and live on deposits from it.
• 20:45
  SPEAKER_01: And when something like that happens, you want to be able to snap your fingers and say, you know, get out of the way.
• 20:50
  SPEAKER_01: But evacuating people is really hard.
• 20:53
  SPEAKER_01: And it's something that you know, whether you're in the developed world or the developing world, people are people are willing to leave their homes for a disaster for a few days or for a couple weeks or something, but not for a really long, long period of time.
• 21:10
  SPEAKER_01: And some of these eruptions, like what's happening at La Supreère or what's happening at Morapi, they can go on for years.
• 21:17
  SPEAKER_01: And so it's a really tough problem, and you know, especially in the developing world where, say, you're in Indonesia and you have farmland and you people living on the flanks of these volcanoes until it gets too sleep to too steep to live on, you know, that's their livelihoods.
• 21:33
  SPEAKER_01: And so there's sort of a an understanding that you can evacuate people for say a few days before they kind of start returning home.
• 21:42
  SPEAKER_01: And so you really want to get the timing right, you know, and at the so right when it starts, you know, it's it's scary, and you wonder, you know, we want to get people out of the way, but but a lot of the art of especially the VDAP group, they're they're masters at this and saying, no, we're not gonna evacuate yet.
• 22:00
  SPEAKER_01: Really getting that timing right, it's really tricky.
• 22:02
  SPEAKER_01: And so that's what they're facing at Lost of Rares is how many people should we evacuate?
• 22:08
  SPEAKER_01: What is the red zone?
• 22:10
  SPEAKER_01: What's the exclusion zone?
• 22:11
  SPEAKER_01: What sort of eruption do we expect?
• 22:14
  SPEAKER_01: If you go back and look at the old deposits from any of these eruptions, you know, sometimes you just get a little skiff of ash and you might have one little dome and then it's over.
• 22:23
  SPEAKER_01: Or sometimes you have an earthquake swarm and the magma doesn't make it to the surface.
• 22:29
  SPEAKER_01: We call those failed eruptions.
• 22:31
  SPEAKER_01: And it's common, you know, it Jesse, you work on intrusive rocks to some, or at least you've seen dikes out in the field.
• 22:38
  SPEAKER_01: They're volcanic rocks that didn't make it to the surface, and they they cool, you know, you you want to be able to try to predict what's going to happen, and it's it's tricky.
• 22:47
  SPEAKER_02: What a tremendous amount of pressure, Andy, because you know, you you have to get the timing right because you can't evacuate people and then come back later when they've moved back in and say, um, now you really have to go.
• 23:00
  SPEAKER_02: Yeah.
• 23:00
  SPEAKER_02: You know, that they're not going to listen.
• 23:02
  SPEAKER_01: Yeah.
• 23:03
  SPEAKER_01: And that's one of the great things about having the speed app and who go out to the world and they sort of keep the tools sharp and get that decision making down to an art.
• 23:12
  SPEAKER_01: And then when we have an eruption in California, where we do have people on the flanks as well.
• 23:17
  SPEAKER_01: Well, when there's an eruption somewhere in our purview, we all rush to help each other out.
• 23:23
  SPEAKER_01: Say there was the eruption on Kilauea in 2018.
• 23:26
  SPEAKER_01: We all went over there and cycled through and helped them out.
• 23:29
  SPEAKER_01: And you you kind of keep the tools sharp for when it's going to happen in your in your backyard.
• 23:34
  SPEAKER_01: But it it is, it's sobering trying to think about how you're going to manage it.
• 23:38
  SPEAKER_03: Yeah, it's a weighty job.
• 23:40
  SPEAKER_03: So, real quick question that uh sort of a bit of a side tangent.
• 23:43
  SPEAKER_03: Is there any role that Kelville plays in uh let's say preemptive uh evacuations where you're like saying, oh, you can't build the development here because this is a dangerous deposit?
• 23:53
  SPEAKER_03: Do you have any sort of kind of insurance or or regulatory role there?
• 23:58
  SPEAKER_01: Yeah, so the USGS doesn't manage land, but we work with our partners, our stakeholders, and we and those are the state or the towns.
• 24:10
  SPEAKER_01: And one thing we do is is we develop these hazard assessments and we we make maps of where lava flows are likely to go or where ash is likely to go, or these areas of elevated concern, and then we give those to the local land managers and and they make the decisions.
• 24:30
  SPEAKER_01: And we don't evacuate anybody either.
• 24:33
  SPEAKER_01: We advise the sheriff on when to evacuate people, or we advise the forest service on how to manage this this crisis.
• 24:41
  SPEAKER_02: And and so they can they can choose to not listen then?
• 24:45
  SPEAKER_02: Well, yeah, I mean it's it's um like a Hollywood script right here.
• 24:49
  SPEAKER_02: Yeah, we're your job.
• 24:52
  SPEAKER_02: You've been featured in a lot of movies, Andrew.
• 24:55
  SPEAKER_01: Pierce Brosnick climbing up inside the volcano here.
• 24:58
  SPEAKER_01: That is a fantastic, yeah, yeah, that's that's really something.
• 25:02
  SPEAKER_01: Um yeah, and so you're we're we um you know, we try to develop relationships and trust with our stakeholders, our partners, and and try to work with them.
• 25:12
  SPEAKER_01: And when there's unrest, they're pretty excited to have us to talk to too, because you know, we we can really gauge what they should be doing.
• 25:20
  SPEAKER_01: And we try to be more and more proactive.
• 25:22
  SPEAKER_01: You know, it this all started in Mount St.
• 25:24
  SPEAKER_01: Helens days before we really had observatories that were were functioning.
• 25:29
  SPEAKER_01: So we learned so much from that.
• 25:31
  SPEAKER_01: The Alaska Volcano Observatory really kicked into high gear when 747 ran into an ash plume.
• 25:38
  SPEAKER_01: You know, it was this close to a few hundred people dying.
• 25:41
  SPEAKER_01: That's the sort of thing that that stimulates formation of our group.
• 25:45
  SPEAKER_01: And and we're always struggling to make better ties and make better maps and advise communities and try to keep them safe.
• 25:55
  SPEAKER_03: What an interesting job.
• 25:56
  SPEAKER_03: I just want to belabor this point because you it really highlights the importance of geoscience.
• 26:00
  SPEAKER_03: I mean, you're making out there making maps of the rocks, and they're used by all sorts of different stakeholders that are around these hazards.
• 26:07
  SPEAKER_03: It's incredible.
• 26:08
  SPEAKER_03: I this is really, really interesting.
• 26:09
  SPEAKER_03: It really is.
• 26:10
  SPEAKER_03: I honestly did not know this about volcano observatories.
• 26:13
  SPEAKER_03: This is very cool.
• 26:14
  SPEAKER_02: Yeah, Andy, um, has there been a recent finding or discovery in your field regarding volcanology that is super important?
• 26:24
  SPEAKER_01: Yeah, so I in my particular field, so so trying to understand, say, histories of volcanoes, the thing that's most interesting to me right now and and the thing that we're we're working on is that volcanoes erupt episodically.
• 26:38
  SPEAKER_01: You have this volcano that's grown over half a million years, and some of them erupt regularly, they're just kind of always always doing their thing, but most will have these periods that they just go crazy.
• 26:54
  SPEAKER_01: They're erupting all the time, different compositions of lavas or explosive materials coming out constantly or over the period of tens of years or hundreds of years or thousands of years.
• 27:06
  SPEAKER_01: And then there are these times when it just seems to sit for 5,000 years.
• 27:10
  SPEAKER_01: And I focus a lot of energy on that and trying to understand the episodicity and how how bad a player one volcano is versus the other.
• 27:22
  SPEAKER_01: And you know, one of the important things obviously is to figure out how old the materials are and see if they came out at the same time.
• 27:29
  SPEAKER_01: But we also use other things like paleomagnetics.
• 27:32
  SPEAKER_03: You guys talked about paleomagnetics, I think, in one of your Yeah, briefly in our in our plate tectonics episode.
• 27:38
  SPEAKER_03: Yeah, yeah, yeah.
• 27:38
  SPEAKER_03: But but I think, you know, brief introduction is that rocks record the magnetic field of Earth, right?
• 27:43
  SPEAKER_03: So how are you using it in this context?
• 27:45
  SPEAKER_01: So the magnetic field is, you know, if you if you look at a map, your your compass doesn't quite point at true north, right?
• 27:54
  SPEAKER_01: There is a true north spin axis to the earth.
• 27:57
  SPEAKER_01: The magnetic north pole is somewhere in Canada, and it actually moves over time, and it's moving pretty constantly.
• 28:04
  SPEAKER_01: And uh right now, in fact, the magnetic north is moving across, it was in Baffin Bay, I think, when I was a kid, and and it's it's now streaking across, headed to Siberia.
• 28:18
  SPEAKER_01: Well, when a volcano erupts, it has a lot of iron, you know, it has a lot of iron in it.
• 28:23
  SPEAKER_01: And as it comes to rest and as it cools, those iron particles with minerals align and they align in that magnetic field.
• 28:32
  SPEAKER_01: And so if you take a core of a lava flow, bring it back to the lab, put it in a cryogenic magnetometer, you can figure out the direction that north was when that lava flow came around.
• 28:48
  SPEAKER_01: And so my colleague Dwayne Champion, he's in he's in our group, in or kind of besties in the in the scientific sense, because he can tell me when a whole bunch of different lava flows or pyroclastic rocks, if they erupted at the same time, he can go out and drill everything, and it's pretty easy and pretty cheap to do that.
• 29:09
  SPEAKER_01: And if he has six different things that all have the same direction, he says, Andy, I got I got these six eruptions, they're all they came out at the same time because they all have the same direction.
• 29:22
  SPEAKER_01: Pick whichever one you want, and we'll have dated that event, right?
• 29:25
  SPEAKER_01: And so I can go out and find the best rock to date and bring it back to my lab and date it.
• 29:33
  SPEAKER_01: And what I do is um relatively expensive and time consuming and I gotta interrupt you.
• 29:40
  SPEAKER_02: So you're telling me that the precision of the magnetic record in these rocks, you can tell when they erupted based upon where they point.
• 29:51
  SPEAKER_01: We can't tell when, but we can tell the direction uh that they erupted at the same time, then.
• 29:58
  SPEAKER_02: Right.
• 29:59
  SPEAKER_01: And so we use it as a correlation tool.
• 30:01
  SPEAKER_01: What we're doing in the field all the time is we're we're looking at these old deposits and we're saying, okay, that's on top of that's on top of that, is on top of that.
• 30:10
  SPEAKER_01: There was a glacier that came down and took a chunk out of this, and then this lava flow came in and filled on that, or a river or something.
• 30:18
  SPEAKER_01: So we're doing a relative dating in our in our heads.
• 30:22
  SPEAKER_02: Would you be able to differentiate between 500 years?
• 30:25
  SPEAKER_02: Oh, yeah.
• 30:25
  SPEAKER_02: Yeah.
• 30:26
  SPEAKER_02: Oh my gosh, are you serious?
• 30:27
  SPEAKER_02: Yeah.
• 30:28
  SPEAKER_02: So the um that's amazing.
• 30:29
  SPEAKER_01: Yeah, the the magnetic field generally, kind of in its normal time, will move such that you can differentiate about a hundred years.
• 30:38
  SPEAKER_01: And so so if it's if it's measurably different.
• 30:41
  SPEAKER_01: So you you if you take good cores, you can kind of get plus or minus five degrees.
• 30:46
  SPEAKER_01: And five degrees is a pretty typical amount that the field will move in a hundred years.
• 30:52
  SPEAKER_02: That's amazing, Andy.
• 30:54
  SPEAKER_02: Uh Jesse, that's a really cool factoid right there.
• 30:56
  SPEAKER_03: Yeah, yeah, that's amazing.
• 30:57
  SPEAKER_03: I didn't know that the uh magnetometers were precise enough to, you know.
• 31:01
  SPEAKER_03: I mean, we're talking about declinations or the offsets, depending on where you are on the planet, of a few few degrees.
• 31:06
  SPEAKER_03: So um that that's really cool.
• 31:09
  SPEAKER_01: We'll talk we'll talk about Shasta a little more later, but there's there's a little volcano that's next to Shasta, and it when I go out and make a talking about Lassen?
• 31:19
  SPEAKER_01: No, this is this is one that's right behind it.
• 31:22
  SPEAKER_01: So it's called Ash Creek Butte.
• 31:24
  SPEAKER_01: It's just uh it's just another lump in the Cascade Range.
• 31:28
  SPEAKER_01: When you make a map of it, you don't see time breaks, you see lava flows on top of lava flows.
• 31:34
  SPEAKER_01: So it looks like something that came out in an afternoon or maybe 20 years or 50 years or 100 years, hard to know.
• 31:42
  SPEAKER_01: And so one of the things we're working on right now is so I've dated, I've dated a few different times, and I can't, the errors on my dates are between one and three thousand years typically.
• 31:54
  SPEAKER_01: So I can't see the difference from the first stuff that came out to the last stuff that came out.
• 31:59
  SPEAKER_01: But my friend Tony, who's another paleo magician, as we call him, the paleo mad guys, uh, came out and he's he's drilling it.
• 32:08
  SPEAKER_01: And and initial results indicate he's he's guessing, yeah, it's definitely less than 100 years, but we see a little bit of variation, so maybe 20 or 30 years.
• 32:17
  SPEAKER_01: And and that's actually really useful for the hazards piece, right?
• 32:21
  SPEAKER_01: Because if something like this comes up in some farmer's backyard, we can say, yeah, it's probably gonna this is gonna probably go on for 20 years.
• 32:30
  SPEAKER_01: You know, it's it's we we really want to sort out that time, that sort of um societal time effect.
• 32:38
  SPEAKER_03: Yeah, that's okay.
• 32:39
  SPEAKER_02: Very, very cool.
• 32:40
  SPEAKER_02: Um, I learned a ton right there.
• 32:42
  SPEAKER_02: That was a cool segment.
• 32:43
  SPEAKER_02: I really appreciate it.
• 32:45
  SPEAKER_02: Really, I'm serious.
• 32:46
  SPEAKER_03: All right.
• 32:46
  SPEAKER_03: So I am a zircon, I'm a geochronologist like yourself.
• 32:51
  SPEAKER_03: Uh, I use a different technique.
• 32:53
  SPEAKER_03: I want to, we have a little bit of a rivalry between our techniques here, I would say.
• 32:57
  SPEAKER_03: Maybe.
• 32:57
  SPEAKER_03: I think zircon uranium lead, the method that I choose has like provided the most information about our planet, but it doesn't work very well for the you know, the modern stuff, the type of rocks you're working with.
• 33:08
  SPEAKER_03: It just does not work for various reasons.
• 33:10
  SPEAKER_03: But you do this really cool method that is equally important, I think, which is you use these gases in minerals, effectively gases, I suppose.
• 33:19
  SPEAKER_03: Maybe you'll frame it better than that, but gases in minerals to date them.
• 33:22
  SPEAKER_03: Can you kind of describe a little bit of the idiosyncrasies of the argon technique that you use and and maybe how you go about getting an actual date from the runaway?
• 33:32
  SPEAKER_03: Hold on.
• 33:33
  SPEAKER_02: Before you begin, though, I have to warn the listener we have two geochronologists now that are about ready to engage in a conversation.
• 33:40
  SPEAKER_02: So, you know, like if you want to push pause on the podcast and pull up a really cool picture of Mount Shasta, now would be the time to do that.
• 33:49
  SPEAKER_02: Because Mount Shasta's super cool, and you know, I think everybody should like just gaze at that maybe while you're listening.
• 33:57
  SPEAKER_02: Oh, yeah, yeah.
• 33:58
  SPEAKER_03: Yeah, using using geocronology to understand our earth is not interviewing at all, right?
• 34:03
  SPEAKER_02: I have no idea what's about to happen here.
• 34:07
  SPEAKER_01: So you know, as much as Jesse was baiting me into an argument about uh why argon's better than uranium led, I'm not gonna bite.
• 34:16
  SPEAKER_02: You're not gonna bite?
• 34:18
  SPEAKER_02: Well, put him in his place, Andy.
• 34:20
  SPEAKER_03: Let him hope to be.
• 34:21
  SPEAKER_03: I was hoping to be smacked down.
• 34:24
  SPEAKER_01: I think it it really depends on the question that you're you're asking.
• 34:29
  SPEAKER_01: Uranium-led zircon is is really great if you want to know when that little zircon crystal grew, right?
• 34:37
  SPEAKER_01: Which I don't really care about.
• 34:39
  SPEAKER_02: And and nobody else does either, Andy.
• 34:42
  SPEAKER_02: So there we go.
• 34:44
  SPEAKER_02: Now we're talking.
• 34:45
  SPEAKER_01: Now we're talking.
• 34:46
  SPEAKER_01: Yeah, yeah, yeah.
• 34:47
  SPEAKER_01: But but and and what Jesse has to do is then tie that crystal to an event, right?
• 34:53
  SPEAKER_01: So he's gotta he's gotta make all sorts of arguments about about why that crystals date, what when it formed, why that matters, and is it even related to the mountain that it's in?
• 35:04
  SPEAKER_01: So it's it's very useful for that.
• 35:06
  SPEAKER_01: And it's it's tremendously useful for lots of you're being too nice right now.
• 35:11
  SPEAKER_01: I you know, some of my some of my best friends work on zircons, and and we we we actually we do a a bit of that ourselves.
• 35:18
  SPEAKER_01: But you know, argon is uh is a really handy tool for telling you when an eruption happens.
• 35:25
  SPEAKER_01: If you have a a rhyolite lava flow that comes out, you can date the zircon, and it might be the age of the eruption, but it might have also grown a couple hundred thousand years before down in the magma chamber.
• 35:38
  SPEAKER_01: And that's interesting, don't get me wrong.
• 35:40
  SPEAKER_02: Because it might not have melted, right?
• 35:42
  SPEAKER_01: Yeah, or it just might have been an early crystallizing phase and it gets locked in and then it sits down there and stews for a long time and then and then gets gets barfed out later on.
• 35:53
  SPEAKER_01: If you only date the zircon, you don't actually know how old the lava flow was necessarily.
• 35:58
  SPEAKER_01: It can help.
• 36:00
  SPEAKER_01: Aragon is is quite good at telling you when the eruption happened.
• 36:04
  SPEAKER_01: So let me just describe the technique.
• 36:07
  SPEAKER_02: All right, now, Andy, let's try to keep this on a level that my mom could understand.
• 36:12
  SPEAKER_02: So you've given us the potassium to argon.
• 36:15
  SPEAKER_01: Okay, so fortunately, you guys spent some time talking about geochronology and and and radioactive decay, right?
• 36:21
  SPEAKER_01: And and so Jesse works on the decay of uranium isotopes to different lead isotopes.
• 36:30
  SPEAKER_01: And it's actually a very complicated convoluted process.
• 36:33
  SPEAKER_01: It takes 10 or 15 steps to get from one to the other.
• 36:37
  SPEAKER_01: Um, and I work on a different radioactive decay system.
• 36:41
  SPEAKER_01: So potassium, the same potassium you have in your bananas and your potatoes, uh, has three isotopes, and and two of those isotopes are stable.
• 36:52
  SPEAKER_01: They're they're not going to change at all.
• 36:54
  SPEAKER_01: And those have uh atomic weights of of 39 and 41.
• 36:59
  SPEAKER_01: Potassium-40, which is a very minor isotope of potassium, is radioactive.
• 37:06
  SPEAKER_01: It's slightly radioactive, it decays to two different things.
• 37:11
  SPEAKER_01: Most of it decays to calcium-40, but a little bit of it decays to argon 40.
• 37:16
  SPEAKER_01: And it does that with.
• 37:17
  SPEAKER_02: Wait a minute.
• 37:18
  SPEAKER_02: Okay, so Andy, I did not know this.
• 37:20
  SPEAKER_02: All right, Jesse, did you know this?
• 37:22
  SPEAKER_01: Yeah.
• 37:22
  SPEAKER_02: You oh I'm just sorry, I'm not the PhD in the room.
• 37:26
  SPEAKER_03: So it's a it's a I didn't know it until I think embarrassingly late in graduate school, to be honest, that it was a dual decay system.
• 37:33
  SPEAKER_03: Yeah.
• 37:34
  SPEAKER_02: Andy, I'm sorry to interrupt the flow, but I just that that threw me for a loop.
• 37:38
  SPEAKER_02: Okay, so you were talking, and you can continue.
• 37:40
  SPEAKER_02: You were talking about going the small amount going from potassium to argon.
• 37:44
  SPEAKER_01: Right.
• 37:44
  SPEAKER_01: So it's a it's a very minor isotope of potassium that's radioactive, and it decays mostly to calcium, but a little bit to argon.
• 37:52
  SPEAKER_01: The potassium, the calcium dating is kind of impossible because there's already so much calcium in rocks and calcium-40.
• 37:59
  SPEAKER_01: You couldn't possibly differentiate the stuff that came from potassium from the regular garden variety, calcium.
• 38:07
  SPEAKER_01: But argon is is special.
• 38:09
  SPEAKER_01: You can actually measure that.
• 38:12
  SPEAKER_01: You can measure the amount of potassium and you can measure the amount of argon quite well.
• 38:18
  SPEAKER_01: And argon's neat because uh well, we're breathing about 1% argon.
• 38:23
  SPEAKER_01: It's a noble gas, so it doesn't want to be chemically attached to anything.
• 38:29
  SPEAKER_01: It's it's just perfectly happy.
• 38:30
  SPEAKER_01: It's like helium or neon.
• 38:33
  SPEAKER_01: Argon's another one of these noble gases.
• 38:36
  SPEAKER_01: And we we can measure it using a mass spectrometer, like Jess's.
• 38:40
  SPEAKER_01: We use it as a different source, a different way to ionize the gas.
• 38:44
  SPEAKER_01: We'll take crystals and we'll heat them up and liberate their argon and measure their argon isotopes.
• 38:52
  SPEAKER_01: The reality is we we we do do what we call conventional KAR dating, potassium argon dating, where we we take a sample and we divide it into two little uh piles and we measure the potassium on one pile and we measure the argon in the other, and then we add it back up.
• 39:12
  SPEAKER_01: What I actually use is a is a slightly more complicated method of potassium argon dating called argon 4039 data.
• 39:22
  SPEAKER_01: To do that, we take the we we do our separate, we we take either our our rock that has minerals that have potassium in them, or we take crystals that are loaded with potassium, and we send them to a nuclear reactor, a small research grade nuclear reactor.
• 39:41
  SPEAKER_01: USGS has one in Denver, and it converts a portion of the stable potassium 39 to radioactive argon 39.
• 39:52
  SPEAKER_01: And so, why would you do that?
• 39:54
  SPEAKER_01: Why would you complicate your life by having to separate the stuff, put it in a reactor, bring it back?
• 39:59
  SPEAKER_03: Well, the advantage is that this is this is one of the coolest technical developments.
• 40:03
  SPEAKER_03: I mean, oh here we go.
• 40:04
  SPEAKER_03: We've been geochronologists now.
• 40:06
  SPEAKER_03: Yeah, yeah.
• 40:07
  SPEAKER_03: But it's so cool.
• 40:07
  SPEAKER_03: Like, what a what an amazing idea to be like, oh, I don't want to measure the potassium in this rock.
• 40:11
  SPEAKER_03: So instead, I'll just convert the potassium to argon and then measure that again.
• 40:16
  SPEAKER_03: Uh it's very cool.
• 40:17
  SPEAKER_03: It's very cool.
• 40:18
  SPEAKER_01: And because the the stuff that we make in the reactor is argon 39 and the stuff that is naturally occurring is argon-40, we just have to measure different isotopes of the same gas.
• 40:29
  SPEAKER_01: And it's easy.
• 40:30
  SPEAKER_01: You know, it's just it's it's dead easy.
• 40:33
  SPEAKER_02: So you're you because you're doing this, you don't have to account for initial daughter isotope present.
• 40:39
  SPEAKER_02: Is that what you're saying?
• 40:40
  SPEAKER_01: That's that's that's part of it.
• 40:42
  SPEAKER_01: So we we there are a lot of complications, of course.
• 40:45
  SPEAKER_01: You know, we're we're breathing all this argon, and so we have to subtract the argon that's in the room.
• 40:50
  SPEAKER_01: We have to get rid of that.
• 40:52
  SPEAKER_01: Um but but the the really nice thing, instead of having to measure the absolute amount of potassium 40 and the absolute amount of argon 40, so we can compare them, we just have to measure a ratio.
• 41:07
  SPEAKER_01: So we we create that argon 39, and then we have standards, things of known age, and we run those to know how much of a dose it got.
• 41:15
  SPEAKER_01: And then all we have to do is measure the relative amount of argon, and and that's easy.
• 41:20
  SPEAKER_01: And and Jesse'll tell you this too.
• 41:22
  SPEAKER_01: The when you're when you have two things that are the same, you're just measuring the ratio, it's much easier than measuring the absolute abundance or something.
• 41:30
  SPEAKER_02: Okay, so Andy, is part of this because argon is a gas, and then in lava, it resets the clock.
• 41:38
  SPEAKER_02: Exactly.
• 41:39
  SPEAKER_02: Right?
• 41:39
  SPEAKER_02: Is that the beauty of using potassium to argon in this with this application, right?
• 41:45
  SPEAKER_01: That's incredibly handy.
• 41:47
  SPEAKER_01: That there is no initial argon 40 in the in the rock or in the mineral.
• 41:54
  SPEAKER_01: That's an assumption.
• 41:55
  SPEAKER_01: It's not always true.
• 41:56
  SPEAKER_01: We have to disprove it.
• 41:57
  SPEAKER_01: We have to we have to prove it every time.
• 41:59
  SPEAKER_01: We have ways that we think we can do that.
• 42:02
  SPEAKER_01: But the the really nice thing is this this solid comes back from the reactor, and all I have to do is put it on an extraction line, heat it up with a laser, clean up the gas a little bit, let it into a spectrometer, you get the age out the other end.
• 42:15
  SPEAKER_02: It's um so what's the half-life of potassium 40?
• 42:18
  SPEAKER_01: 1.25 billion years, one and a quarter billion years.
• 42:24
  SPEAKER_01: The margin of error, it scales with the age, but typically the best stuff for like 100 million-year-old rocks is is about a tenth of a percent.
• 42:33
  SPEAKER_02: And oh my gosh.
• 42:35
  SPEAKER_02: And so you Jesse, did you know that?
• 42:37
  SPEAKER_03: Yeah, that's it's it's really good.
• 42:39
  SPEAKER_01: Yeah, it's it's it's outstanding.
• 42:41
  SPEAKER_01: It's it's actually pretty similar, similar to uranium lead.
• 42:45
  SPEAKER_01: Uh the errors are actually a little bit smaller on uranium lead.
• 42:49
  SPEAKER_03: But but let's go let's convert that to you know in raw ages.
• 42:53
  SPEAKER_03: So if we're measuring a million-year-old rock, what's the the age uh uncertainty that we would get out of that date?
• 42:59
  SPEAKER_01: So it'd be about 10,000 years.
• 43:01
  SPEAKER_03: Okay, and if we scale that down to your 10,000-year-old you know, Shastina rock or whatever, uh, you're getting uncertainties on that age that are well, we run into some problems when we get really young because there's so little radiogenic argon and so much atmospheric argon that contaminates everything that would that we kind of bottom out.
• 43:22
  SPEAKER_01: And and the best stuff on a rock, like on a shasta rock, I can usually get plus or minus about a thousand years.
• 43:29
  SPEAKER_01: Okay.
• 43:29
  SPEAKER_01: If we if we work really hard, this is a great story, actually.
• 43:33
  SPEAKER_01: My predecessor started this, and when I started, we I helped him finish it, decided he wanted to date the the 79 AD eruption of Vesuvius.
• 43:42
  SPEAKER_01: So we know when that happened.
• 43:44
  SPEAKER_01: It was August 79 AD.
• 43:47
  SPEAKER_01: Pliny the Younger was standing in Naples looking across at Vesuvius.
• 43:52
  SPEAKER_01: His uncle was uh Pliny the Elder, was trying to rescue people from Pompeii.
• 43:59
  SPEAKER_01: And And Pliny the Younger.
• 44:01
  SPEAKER_03: This was 790 AD.
• 44:02
  SPEAKER_03: Is that we said the date?
• 44:03
  SPEAKER_03: Sorry.
• 44:04
  SPEAKER_01: No, 79.
• 44:05
  SPEAKER_01: 79.
• 44:06
  SPEAKER_01: 79 AD.
• 44:07
  SPEAKER_01: So almost 2000 years ago.
• 44:09
  SPEAKER_01: Okay, gotcha.
• 44:10
  SPEAKER_01: And he drew this picture of this mushroom cloud.
• 44:13
  SPEAKER_01: And that's why we call it a Plinian eruption.
• 44:16
  SPEAKER_01: It's because Pliny the Younger drew this mushroom cloud that was above Vesuvius.
• 44:22
  SPEAKER_01: So we we went over there and collected rocks, pumice from that eruption, and we separated out a very potassium-rich mineral called sanity.
• 44:32
  SPEAKER_01: And we dated it.
• 44:34
  SPEAKER_01: And we we spent about three weeks dating it.
• 44:38
  SPEAKER_01: We did it multiple times, over and over and over.
• 44:41
  SPEAKER_01: And we would get essentially the right number, plus or minus about 200 years.
• 44:46
  SPEAKER_01: But we did it so many times that we knocked the errors down until we got plus or minus 90 years.
• 44:52
  SPEAKER_01: So we got the right year.
• 44:55
  SPEAKER_01: We also stopped when we got the right year, right?
• 44:57
  SPEAKER_01: So it was it was we were you know a little bit too old, they'd average themselves out, a little too old, a little too young.
• 45:03
  SPEAKER_01: And then when we stopped, we knew it was time to start.
• 45:05
  SPEAKER_02: Okay, so that's a really cool story.
• 45:06
  SPEAKER_02: Does that have application to things that are much, much older than what you learned from doing this?
• 45:12
  SPEAKER_01: Well, it it does a few things.
• 45:14
  SPEAKER_03: Sorry, could you let me let me interrupt?
• 45:16
  SPEAKER_03: I want to I want to kind of describe you know visually what you just described there because I I think we need to kind of visualize this.
• 45:22
  SPEAKER_03: This is not an easy thing to visualize.
• 45:23
  SPEAKER_03: So you're saying we have this point in time, 79 AD, that we know this eruption happened, and you're getting an age measurement.
• 45:30
  SPEAKER_03: Like, what is the first number you get in?
• 45:32
  SPEAKER_03: Are you getting like 200 AD plus or minus 90 years?
• 45:36
  SPEAKER_03: And that's the that's the range.
• 45:37
  SPEAKER_03: Is that like something on that scale?
• 45:39
  SPEAKER_01: Perhaps um the first time we did it, we would get zero AD or kind of the birth of Christ, right?
• 45:46
  SPEAKER_01: Plus or minus 200 years.
• 45:48
  SPEAKER_01: And then the next time maybe we get 30 years AD, plus or minus 200 years, and then we get a few that are too young.
• 45:55
  SPEAKER_01: So maybe they happened 120 AD, 120 common era with that error.
• 46:02
  SPEAKER_01: And if you do things a whole bunch of times, you can sum them statistically and reduce your error, reduce that error envelope.
• 46:13
  SPEAKER_02: So you go down below 200 plus or minus 200 years.
• 46:17
  SPEAKER_01: Statistically, we got uh an age that was the right year, or you know, with error the right year.
• 46:25
  SPEAKER_02: Yeah.
• 46:26
  SPEAKER_01: With an with an error, an analytical error, an uncertainty of 90 years.
• 46:32
  SPEAKER_03: Wow, that's really cool.
• 46:34
  SPEAKER_03: So the way to visualize this, I just want to paint again, paint this picture and go back to it.
• 46:37
  SPEAKER_03: If you visualize this with like you know, a time chart, we know the age.
• 46:41
  SPEAKER_03: There's like a spike in the ground of the age, 79 AD.
• 46:44
  SPEAKER_03: We're getting like this uncertainty around it.
• 46:46
  SPEAKER_03: So we're getting this kind of squishy gray band in that age time.
• 46:50
  SPEAKER_03: But if you stack up a whole bunch of those squishy gray bands that are offset from knowing one another a little bit, the average of all these measurements becomes actually more precise.
• 46:58
  SPEAKER_03: So the more numbers you have, the more N, the more precise this thing actually gets.
• 47:02
  SPEAKER_03: So you're kind of decreasing your uncertainties or increasing your precision by getting more data, right?
• 47:08
  SPEAKER_03: Yeah, you're driving this down.
• 47:10
  SPEAKER_02: Yeah.
• 47:11
  SPEAKER_02: So I I am feeling a little left out because I don't have a lab.
• 47:15
  SPEAKER_02: You know, Jetsy has a lab, Andy is a lab.
• 47:17
  SPEAKER_02: Chris does not have a lab.
• 47:19
  SPEAKER_02: Um Chris.
• 47:21
  SPEAKER_03: Uh oh, you don't date your rocks, you don't date your own rocks in your lab.
• 47:25
  SPEAKER_02: I do not date my own rocks.
• 47:27
  SPEAKER_02: Um, so Andy, we always ask this question.
• 47:30
  SPEAKER_02: It's one of my favorite things to ask.
• 47:33
  SPEAKER_02: Um, I think we all have one.
• 47:36
  SPEAKER_02: What has been your best day as a geoscientist?
• 47:40
  SPEAKER_01: It's a tough question.
• 47:41
  SPEAKER_01: There have been a lot of best days, and you know, it really um I I love my job.
• 47:48
  SPEAKER_01: You know, I I I I love the the laboratory work.
• 47:52
  SPEAKER_01: I I like looking at rocks in the lab.
• 47:55
  SPEAKER_01: I love being in the field.
• 47:57
  SPEAKER_01: So I've I've I've I've done a lot of field work in Alaska and scattered places um around the world.
• 48:04
  SPEAKER_01: But my favorite day is um it's on Mount Shasta.
• 48:10
  SPEAKER_01: And we we went up the north side and we were we were headed up to the summit.
• 48:16
  SPEAKER_01: And I was with I I've had the great fortune to um work with the the US Forest Service uh climbing rangers.
• 48:24
  SPEAKER_01: They're the guys that keep people safe on the mountain, and it's a hard job, and they rescue people, they carry people who died down off the mountain.
• 48:33
  SPEAKER_01: And it's a delightful bunch of people, um, men and women, and they help me when I need help.
• 48:41
  SPEAKER_01: Uh so if there's a particularly hazardous place I need to get to to sample the right rock, I call up the lead climbing ranger, and either he goes with me or sends one of his people up with me and they take care of the safety.
• 48:56
  SPEAKER_01: And it's just it's dreamy because I don't have to worry about all I have to do is is you know make sure I don't fall down and and you know, protected.
• 49:05
  SPEAKER_01: I'm protected, and and they've got radios and the works.
• 49:08
  SPEAKER_01: And and so there was a day when I was um climbing the north side, the Hotland Bowling route, with um two of these rangers, Force Coots and Nick Myers, and uh uh a wonderful woman who who worked for us uh named Heather Blake.
• 49:21
  SPEAKER_01: And the four of us uh camped out at 10,000 feet and then got an early start and and headed up the Hotland Bowlin route.
• 49:27
  SPEAKER_01: And it was a spectacular day, it was beautiful.
• 49:29
  SPEAKER_01: And we went up and there's a a nice step at about I think it's about 12,000, yeah, a little over 12,000 feet.
• 49:38
  SPEAKER_01: And we stopped and and had a candy bar and relaxed a little bit.
• 49:43
  SPEAKER_01: There was a a dome, uh, it's the head wall of the Hotlam Glacier, although I call it the Hotlam Head Wall.
• 49:51
  SPEAKER_01: It's an old dome that sticks up.
• 49:53
  SPEAKER_01: And I said, Oh, you know, I really want to get a sample of that someday.
• 49:56
  SPEAKER_01: We you know, I we've got to figure out the the timing.
• 49:59
  SPEAKER_01: And and Nick Myers turns to me and said, You know, I was over there the other day, and it looks like the bridge is in place.
• 50:06
  SPEAKER_01: It looks, it just looks uh it looks great.
• 50:09
  SPEAKER_01: Let's go give it a shot.
• 50:11
  SPEAKER_01: And hauled out the rope.
• 50:13
  SPEAKER_01: And so he laid me out onto the glacier.
• 50:16
  SPEAKER_01: I was down at the bottom of the headwall, and I got a beautiful sample.
• 50:21
  SPEAKER_01: We're looking for a pretty specialized type of material, really dense, doesn't have a lot of vesicles, these gas pockets, and it's very hard to date glass.
• 50:29
  SPEAKER_01: It's much easier to date crystalline material.
• 50:32
  SPEAKER_01: And I got a beautiful sample, and it was um the the snow was perfect, the conditions were perfect, and I felt so safe because you know the climbing rangers on the other end of the rope.
• 50:44
  SPEAKER_01: And it was almost like I was floating, you know.
• 50:46
  SPEAKER_01: Usually in that sort of place, I'm I'm scared out of my mind, or you know, you just sort of you don't want a rock to fall on you.
• 50:52
  SPEAKER_01: But I just remember it was like I was floating out there, I got the rock and I floated back.
• 50:58
  SPEAKER_01: And I will never forget that feeling.
• 51:00
  SPEAKER_01: And I got this fantastic sample.
• 51:02
  SPEAKER_01: It was it's it's old, it's 10 well old for the hotlum cone, the youngest part of Shasta, 10,000-year-old rock.
• 51:11
  SPEAKER_01: And um, oh, it was great.
• 51:13
  SPEAKER_01: And then we then we trotted up to the top, collected some samples, and and bailed out.
• 51:18
  SPEAKER_02: You didn't trot up to the top, Andy.
• 51:20
  SPEAKER_02: Come on now.
• 51:20
  SPEAKER_02: I know better.
• 51:22
  SPEAKER_01: It's it's a tough time.
• 51:24
  SPEAKER_02: It's it's really you know, one of the things I love about it is uh the bags that you're supposed to go to the bathroom in.
• 51:32
  SPEAKER_02: They have the bullseye on them, you know, and it's just it's I've never seen anything like it anywhere else.
• 51:38
  SPEAKER_01: So it's a locally sourced, locally designed bag to take a dump in.
• 51:43
  SPEAKER_02: Yeah, cool.
• 51:44
  SPEAKER_02: There you go.
• 51:44
  SPEAKER_02: It is it is so clever that's got lime in it and all that.
• 51:48
  SPEAKER_02: It's good to go.
• 51:49
  SPEAKER_03: That sounds like such a good story, though.
• 51:50
  SPEAKER_03: I mean, apart from the bag, these bags that you're taking dumps in.
• 51:53
  SPEAKER_02: I mean, it's just well, you gotta pack it out with you, and that's what do you yeah, okay, fair enough.
• 51:57
  SPEAKER_03: But the perfect sample, perfect day.
• 51:59
  SPEAKER_03: I mean, uh that that's a great best day as a as a geoscientist story.
• 52:04
  SPEAKER_03: That that's really great.
• 52:05
  SPEAKER_03: It was a good one.
• 52:06
  SPEAKER_02: I really, really appreciate you talking to us, Andy.
• 52:09
  SPEAKER_03: Um yeah, this has been great.
• 52:11
  SPEAKER_03: Thank you very much for the time.
• 52:13
  SPEAKER_02: I feel like you're a bit of a kindred spirit, to be honest with you.
• 52:16
  SPEAKER_01: Well, likewise, you know, I I really I um and I really got that you that comes across in your podcast.
• 52:22
  SPEAKER_01: I mean, you guys are exactly like you sound, you know, just just genuine and nature-loving or kind of earth-loving people, and then teaching and and you know, the motivating Jesse to actually turn this into a career is that's that's a great origin story for for a geologist, really, is to have a great seventh grade class or whatever it was.
• 52:42
  SPEAKER_01: And it's really true that it does get short-triffed in middle school and and whatever.
• 52:49
  SPEAKER_02: We fight it.
• 52:50
  SPEAKER_02: I'm at the high school and we're still we're fighting the battle all the time.
• 52:54
  SPEAKER_01: Well, just the the ridiculous, you know, you you listen to Elon Musk and talk about you know, we we've got to make Mars um habitable, habitable.
• 53:04
  SPEAKER_01: It's ridiculous.
• 53:05
  SPEAKER_01: It's it's 85 billion times easier to just take care of what we have.
• 53:09
  SPEAKER_02: That's exactly, you know, I teach astronomy, and uh, you know, one of my students uh who's a one of the brightest students I've ever had, she presented on that, and and then her conclusion was why are we doing this?
• 53:23
  SPEAKER_02: You know, why are we talking about you know inhabiting Mars when we have this planet that is good to go?
• 53:30
  SPEAKER_02: You know, we need to take care of the one we have.
• 53:32
  SPEAKER_01: Yeah, yeah, and actually working on volcanoes has been interesting too, because you kind of have to become a glaciologist too, because there's there's such an interplay between the ice and the eruptions.
• 53:44
  SPEAKER_01: And you know, I've been places in Alaska that are um devoid of ice now, but you look at the air photos and the maps from the 1950s, and it was glacier, you know, and and these are maritime glaciers where you know you were under 30, you know, 20 meters of ice there, and and you're now on just this spick and span clean surface.
• 54:04
  SPEAKER_01: It's it's it's terrifying, really.
• 54:08
  SPEAKER_03: I really, really appreciate talking to you.
• 54:10
  SPEAKER_03: Yeah, it'd be great to hang out, you know, in person.
• 54:12
  SPEAKER_03: Really appreciate the time, Andy.
• 54:14
  SPEAKER_03: This has been awesome.
• 54:15
  SPEAKER_01: Likewise, thanks for doing this.
• 54:16
  SPEAKER_01: It's really fun.
• 54:17
  SPEAKER_01: Well done.
• 54:18
  SPEAKER_01: Well, you guys are great.
• 54:19
  SPEAKER_01: Thank you.
• 54:22
  SPEAKER_03: Hey, that's a wrap on our re-release interview with Dr.
• 54:25
  SPEAKER_03: Andrew Culvert.
• 54:26
  SPEAKER_03: We are still on a break, and next week we're gonna have more re-release volcanology content for you.
• 54:30
  SPEAKER_03: You can follow us on all the social medias at Planet Geocast, send us an email, planetgeocast at gmail.com, and go to our website, planetgeocast.com.
• 54:38
  SPEAKER_03: There you can support us, look at all the episodes, learn about us, and also check out our Camp Geo, the conversational textbook for geology.
• 54:47
  SPEAKER_03: We are uploading new content all the time, and actually, our volcanoes chapter is probably up now.
• 54:54
  SPEAKER_03: So check that out.
• 54:55
  SPEAKER_03: You can learn all about volcanoes like you would in a college level intro to geology class.
• 55:01
  SPEAKER_03: So check that out and let us know what you think.