Talk Description to Me

Episode 87 - Hunga Tonga Volcano and Tsunami

January 22, 2022 Christine Malec and JJ Hunt Season 4 Episode 87
Talk Description to Me
Episode 87 - Hunga Tonga Volcano and Tsunami
Show Notes Transcript Chapter Markers

On January 15th 2022, an underwater volcano erupted in the Pacific Island nation of Tonga, sending an ash cloud 100,000 feet in the air.  The massive eruption was clearly visible from space, and sparked a tsunami that rocked Pacific coastlines from New Zealand to Japan, Peru to Canada. Today, Christine and JJ describe satellite images of the blooming ash cloud, visualizations of the eruption's shockwave, and videos of the resulting tsunami.

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JJ Hunt:

Talk description to me with Christine Malec and JJ Hunt.

Christine Malec:

Hi, I'm Christine Malec.

JJ Hunt:

And I'm JJ Hunt. This is talk description to me where the visuals of current events and the world around us get hashed out in description rich conversations.

Christine Malec:

Several episodes ago, we talked about volcanoes mostly in the context of St. Vincent. And this past week, there was an underwater eruption of the Hunga, Tonga volcano and that had a lot of aspects that were interesting, visually. So we thought we would talk about about that in various iterations and manifestations of the visuals of that. So, JJ, what were some of the first visuals that we got about that event.

JJ Hunt:

So from the volcano, the Hunga Tonga volcano in the South Pacific erupted on Saturday, the 15th. And one of the first things I actually think that came out about it was the tsunami warning, the tsunami warning spread very, very quickly. And so that's kind of one of the things that, you know, that got my attention. Tsunamis are devastating things. And I was quite concerned that the visuals of that we're going to be extreme. Turns out that they the visuals of this particular tsunami weren't as bad as they could have been. But that was the initial thing that I think a lot of the world heard about. And then some of the visuals, some of the satellite images of the of the initial eruption started to come out, not as many visuals from the actual explosion, the eruption of the volcano, because this is an underwater volcano, that's part of a an unpopulated island. There weren't as many videos of the actual scene itself. So we didn't get quite this many videos of that. We instead got a lot of satellite images. And then, later visualizations of the effects of this eruption on the globe, really.

Christine Malec:

Is there a reasonable way to compare the visuals from St. Vincent and what we saw on the weekend?

JJ Hunt:

Yeah, we got a tweet from from one of our followers on Yeah, asking us, if this eruption looked like the eruption that, you know, we described back in April that that the one in the Caribbean island of St. Vincent, and it's a great question. The short answer is do those two eruptions look similar? And the short answer is yes. If you had side by side footage of the initial eruptions, they would look quite similar, but there are a few key differences. So let's back up a bit and talk a talk specifically about the Hunga Tonga eruption. And then we can compare the two. So like I said, this is an uninhabited island in the South Pacific. So if you're looking at a Mercator map projection, like this is the kind of map projection that we talked about, in Episode 81. I think in December, if you you know, find Australia on the map, move straight to the right, you're gonna pass over New Zealand and then you'll come to the Tonga islands, right near the International Dateline, the island of Hunga, Tonga was actually two separate islands with an underwater volcano between them that was until a few years ago. And then this underwater volcano, the activity from it filled in the space between these two islands, and it became one island, so it became more visibly recognizable as a volcano because even though it's an underwater volcano, crater started to form in this in this new land, this new curved strip of ash gray land between these two what looks like grains of rice islands in this vast Pacific Ocean. So that was what the island what the Hunga Tonga volcano looked like until Friday, January 14. And then on the 14th, there was a significant eruption ash rising to 10s of 1000s of feet. It registered on satellites, it was a significant eruption. And then there was enough time after that explosion settled down for satellite images to come out of the new island. So lo and behold, the island had been split into two again, the area with the crater in the middle was gone, and it was just replaced with kind of what looked like a blanket of floating gray ash on the water. So that image the images of this new island, those were taken just a few hours before the massive explosion on Saturday the 15th. So that's how we get up to the 15th. Lots of similarities between St Vincent and the major explosion on the 15th. Both had massive ash clouds, so huge gray plumes that shot straight high into the air and then started to mushroom up the top. Not big explosions of red hot lava shooting into the aeronaut that I've seen. In the St. Vincent eruption, the ash plume reached, I've seen numbers like 26,000 to 32,000 feet. In the Hunga Tonga explosion or eruption pardon me, the the ash code reached 100,000 feet. So this is three times higher than commercial airplanes fly. We're actually talking into the stratosphere here. This is apparently fairly rare for an ash cloud to reach that high. So the Hunga, Tonga, much bigger, and again, also an underwater volcano. So that changes a little bit how it looks like I've described before and after the eruption, but it actually had surprisingly little impact on the look of the ash cloud. The other difference apparently, there was an incredible amount of lightning. During the hunger Tanga eruption, I've read some numbers that are just unbelievable, like 200,000 lightning strikes in the hour after the main Eruption 400,000 lightning strikes in a seven hour period, I mean, numbers that boggle the mind, the only footage that I've seen of the lightning is actually from the day before from the eruption on the 14th. And these were like jagged bolts of lightning kind of pinkish in color, coming down from the cap of the mushroom shaped ash cloud, and then disappearing into the column of ash rising up at the center. So those are the similarities between the two eruptions. But for our purposes, the biggest difference is the kind of footage that we have access to. So St. Vincent is a populated island when it erupted. There were lots of people who just switched on their cameras turned on their phones. And so the world had access to images and cell phone videos of the actual eruption itself. The initial ash cloud, the chaos, the aftermath, all from the ground level. That was the visual information that kind of spread around social media and the news reports. But Hunga Tonga, not a populated island, we have gotten some footage from the main island of Tonga, but really not that much. And that's in no small part because the erupting underwater volcano damaged the underwater internet cable that keeps Tonga connected to the rest of the world, it's actually been severed, and it's apparently going to be two weeks before it's repaired. So the footage that was being shot on the nearby island of Tonga isn't being released, we haven't gotten access to it because we don't have an internet connection. And then because the size of the eruption was so much greater the scale of Hunga Tonga was that that eruption was so much bigger, it has had a more global impact. So there's lots of satellite footage of this eruption, staggering satellite footage, and the resulting pressure wave and tsunami waves. They made their way all around the globe. So news outlets have been pumping out remarkable satellite images and visualizations that demonstrate the global scale. That's also part of the story. So lots of visuals to talk about, but the visuals of that we get from Hunga Tonga are quite different than the visuals that we had access to from the St. Vincent explosion eruption.

Christine Malec:

I've got a few questions. Lightning, is that a function of the volcano? I know that's not a description question. But have you read that lightning is a byproduct somehow?

JJ Hunt:

Yeah, apparently, the ash, the charges that are in the air, it's just it's an environment that's conducive to lightning strikes that again, I don't know exactly how this works. And because we don't have footage of the you know, of the moment, we don't, I don't have video of this to look at a guy I've seen visualizations that are tracking the data of like, you know, here's when these charges are, you know, going off inside the volcano, or inside the eruption. It's really inside the ash cloud. Apparently it's the combination of dust of energy release of air temperatures, and then a whole bunch of Other, frankly, science that is over my, over my head. But yeah, apparently this is a phenomenon. This is an understood phenomenon that inside the ash cloud of erupting volcanoes, there are there is the the mix of things that are necessary for lightning storms. I hadn't heard of this before. Fascinating.

Christine Malec:

Yeah, me either. Also, what you're describing in hunger talk is enormous forces. And yet, we're not seeing them from sea level the way you did in St. Vincent. So I'm wondering about scale, and whether something that you see, mostly from a satellite image, if it's possible to understand it as being as huge as it actually is, because it's there's scale issues involved is that difficult to parse visually?

JJ Hunt:

Well, it becomes easier when you look at it from a satellite image, because you are looking at the entire globe. And you realize if, if I can visually see this, this clearly, on the surface of the planet like this is this is on a planetary scale. So let's just say, if I take one of those satellite images of the earth, and I enlarge it on my laptop, so that the Earth takes up the entire screen. So let's just say that's what the earth is maybe eight inches across. The expanding ash cloud grows to be almost the size of a dime. It is easily recognizable from space. It's not like, Oh, if you zoom in here, you can see No, no, it is clearly visible. As it gets bigger and bigger and bigger. It just amazing. So in some of the satellite images I've seen, the Earth looks like it's you know, it's big, blue, beautiful self, the landmasses, those are fairly clear, partially obscured by swirls of clouds. So often in the satellite images, the landmasses and political borders are outlined in thin white lines. And because this eruption was in the Pacific, the Earth is tilted with that region in focus. So often, in images of this eruption, you're seeing Australia and New Zealand are both in frame. But again, Tonga is well out into the ocean. So in the satellite images, and then the satellite image clips, so they put all of these images one after the other kind of like a stop action movie, like a flipbook. So you can see what looks like a choppy video of the ash cloud expanding, it looks like the ash cloud appears in the middle of the ocean, out of nowhere, because this is an underwater volcano. And the Pacific Islands are small enough at this distance, that they're not really visible. So when you're watching the satellite footage, this blooming ash cloud appears out of nowhere. And there are other angles, you can get some angles that are quite a bit closer. So I've seen some of those. They're their satellite images, but they're like relative close up. So you're zoomed in to see about one quarter of the globe, and the curve of the Earth is cutting the corner of your screen. Again, no landmasses are visible, some of the islands might be blocked by clouds. But we're close enough to the area of interest that New Zealand doesn't even make it into the frame, nothing but ocean topped by swirls and bands of cloud. And then seemingly out of the blue, this ash cloud bursts to life. And at this close up at this kind of vantage point on these satellite images. They're really remarkable because it's this happened around sunset. So the shadow that falls on the planet, as knight comes in this, the shadow sweeps across the globe in a straight line. And it's doing this just as the ash cloud is blooming. And what this does is it really highlights the topography of the cloud. The detailing is remarkable. It's like it's dramatically lit. So you see the waves of cloud expanding, you can see concentric rippling rings, those are visible inside this expanding cloud. At moments. The top of this cloud looks like the head of a cauliflower. And then other moments, it seems like it's flattening out and it looks more like the cap of an oyster mushroom. peaks and valleys the topography of the ash are so dramatically lit because of this sunset line moving in this shadow coming across. It's super cinematic, and for me, like just moving beyond the visuals, this shadow line seeing the shadow line move is also a reminder of the connection to the cycles of the planet. Right this is it place in the solar system, the way the line sweeps over this growing ash cloud without pausing. It's both, I find it both disturbing and reassuring. The other thing that's remarkable is from this vantage point, not only is the ash cloud visible, but the pressure wave the shockwave that's also visible I it kind of blows my mind. I found a YouTuber named Scott Manley. He's, you know, citizen scientist who gathered a lot of amazing imagery and visualizations from from news agencies, but also directly from monitoring sources. So I don't normally use YouTubers as as resources. But this guy, Scott Manley really seemed to have access to some very interesting things, he posted a satellite image from this one of these somewhat close up vantage points that we've been talking about. And he looked at it in in the near infrared. And so visually, this images is black and white, and it's a little bit darker than some of the other images. But what this looks like in the near infrared, looking at it in this contrast, what it makes clear is this pressure wave, this is a ghostly ring that expands like a growing doughnut. And it starts small in the very moment that the ash cloud erupts. And then it expands very quickly, even more quickly than the ash cloud. Apparently, this this pressure wave was traveling at greater than the speed of sound. And I have watched it over and over again, trying to figure out how to describe what I'm seeing, like how is my eye detecting this expanding ring, it's not clear it's a, it's translucent. As it's washing over the planet. Maybe the image behind it is a little bit lighter. As it expands, maybe it's a little bit out of focus. So it's like, it's blurry or gauzey. But somehow it's, it's fairly easy to detect, it's I can, I can clearly see it. As it expands, it becomes less visible it, it visually starts to dissipate. But we know that it keeps sweeping this expanding ring, this expanding pressure wave sweeps around the globe. We know this because the pressure changes were detected by sensors in Japan, in the US and in Canada. So we can look to the visualizations of of those pressure changes, and we can see this shockwave move around the world.

Christine Malec:

So what did people start doing with ways to visualize this and visualizations?

JJ Hunt:

So totally fascinating to me, I didn't know a lot about this. So of course, lots of weather stations are set up to track pressure right for our local weather reports, you know, the high pressure systems moving in, so lots of tracking of of air pressure, or lots of tracking of pressure in our daily weather reports and on weather channels. There, they'll often show a map of a country or a region and drawn onto that map will be a bendy wavy line that's dotted with little blue or red triangles pointing in one direction or the other. They will be marked up with capital blue letter H's for high, and capital red letter L's for low pressure. And then what they do is they play a clip like one of these stop motion clips in it. And that shows the lines, these bendy lines moving across the map, sometimes shifting as whatever pressure system they're tracking moves across the land. That's usually how information about pressure is conveyed to the public. But there are other ways to convey that data from pressure sensors to and apparently these pressure sensors are all over the place. Again, this YouTuber Scott Manley and the Washington Post. They both featured a data map of the US that was compiled by a gentleman named Darryl Herzman of Iowa State University. This is a simple white map of the US with the state borders indicated by thin black lines. And the map is covered with dots. These are dots ranging from dark blue through pale blue to pale red down to deep red. So this is a scale where the darker blue represents higher air pressure and the deeper red lower air pressure. And this visualization is a is a series of data snapshots taken every 15 minutes. And when those snapshots are shown one after the other turns into this little flipbook that we keep talking about and the patterns become clearer. So at the start of the visualization, the map is dotted with pale colors. So pale blues, pale reds. So what this tells us is no where is the pressure very high or very low, and there's no obvious pattern, it's just dotted with these pale colors, blues and reds. And then starting at our lower left in California, a diagonal line of darker blue dots suddenly appears. And they start to spread out, they start to move and move up toward our upper right toward the No, the northeast, they fade a little bit, they get a little bit dimmer, as they go up toward the northeast, and immediately behind them is a wave of red, darker red, sweeping in the same direction. So these dots go from a mix of pale colors to this line of clearly blue followed by clearly red in a discernible wave that sweeps from the southwest coast to the north east. And there's another map of Japan where the exact same phenomenon, it's even more clear, it's the same map concept. But because the landmass is much smaller and the dots appear much bigger and more tightly packed. It's just super clear this fast moving wave of high pressure, immediately followed by low pressure sweeping across this narrow island nation, first blue than red. You can see it sweeping across it did totally blew my mind why I've never experienced anything like seeing a visualization of shockwave moving across the globe. Fascinating.

Christine Malec:

Ya, ya. Oh my gosh. There was concern about tsunami that was one of the earliest concerns, of course, and tsunami is one of those phenomenon that I know is visually very, very striking and frightening, really, and it's in its force.

JJ Hunt:

Immediately after the eruption the tsunami warnings were sent out.Sserious concern in Japan warnings up and down the west coast of North America. Well, really all of the Americas. A lot of warnings that, you know, clear that clear the beaches, clear the ports in some places they were evacuating some places in Japan were evacuated. Of course, the main island of Tonga, and nearby New Zealand were the worst hit. There's not a ton of footage of the tsunami hitting Tonga, because like I said, the internet went down so quickly, that link hasn't been reestablished yet. There were a handful of videos of the moment that the tsunami hit that made it off of the island before the internet went down. I've seen one video that features a beach in late afternoon. So this is a video filmed from across the street. Looks like it's probably filmed with a phone, the water. The as it approaches, it looks choppy, there are waves rolling in toward the beach toward the camera, and then a wave, which I have to say just visually it doesn't look particularly huge. It pushes in onto the beach, and it doesn't stop. And that's the thing with the tsunami that just doesn't stop. So this wave comes in over the beach. It crashes right past a row of scraggly trees, and then it breaks over a low stone wall. I don't know how tall it is. But I'm guessing lower than waist high. But this wave just goes right over the top of this stone wall. And then it washes over what appears to be an already wet road. And the water just keeps pushing inland it starts to get a little frothy at this point. It's churning because it's going over the road it's going over some rough surfaces. It pushes down wire fences, as as the wave rushes into people's yards. And then the camera which has been kind of moving to track the water as it as it comes in onto land. The camera pans back towards the beach at this point. And it looks like other waves are continuing to roll in. Even as the first wave is continuing to push on the wave hasn't started to pull back yet. And more waves are coming in. There are other videos that have seen filmed from inside of houses. There was one woman who was on a FaceTime call while this tsunami was coming in. And that's why this footage has been released because it was it was happening at live at the moment she was filming as the tsunami was coming in. And she filmed outside of her window and there's water rushing down streets like flowing like rivers between the houses. There's footage of water rushing into a small church with the water as high as the seats on the rows of wooden pews. They're this footage of wooden fences being washed away even a few cars being washed away. Like I said, limited footage of the initial tsunami and difficult to get information and images. I think the general understanding is that there was lots of damage to property in Tonga on the main island of Tonga. And I think the understanding is that almost all of the houses on the outer islands were likely white doubt, damage to boats damage to the coastline. But so far, the death toll has been mercifully low in Tonga, and even though the tsunami went around the world, I don't think the damage was catastrophic. The boats in marinas in New Zealand were tossed about, I saw a news report where someone talked about a catamaran in a marina being picked up and thrown over another boat. So you know, some big waves, some big activity. I read that a two people did die in Peru, when big waves washed over a northern port. Yeah, there was some initial concern that the tsunami had the potential to be really quite devastating. But in the end, I think it was largely manageable. Not to... you know, people have died, there's devastation, but I think the understanding is that it could have been so much worse.

Christine Malec:

Tsunamis have a reputation for being catastrophic in visual terms. Can we do? Can we maybe talk a little bit about ones that you've seen in the past? And what does the classic terrifying, super destructive tsunami look like?

JJ Hunt:

Yeah, so the Hollywood version of a tsunami is not particularly accurate, surprise surprise. So the Hollywood version takes the image of a big cresting wave, and just blows it up to an epic scale. So a huge surfing wave approaches a waterfront city and it crests as it reaches the shore. So, you know, the big curving wave tips down, the water crashes down onto the city. Very, very dramatic. But it's not what tsunamis tend to look like. And then we're going to talk in general terms. So I'm going to use words like 10. But the videos that I've seen of tsunamis don't look anything like that. First of all, tsunamis don't crest, they don't have that action where they curve up, the water gets high on the top, and then it comes crashing down like a surfing wave. That doesn't happen with tsunamis. Tsunamis are walls of water that push inland relentlessly. And as they rush over different surfaces, roads, houses, trees, the water does get churned up. It doesn't come, you know, cresting and crashing down, it gets churned up, it gets frothy, it gets rolling at the front of the wave. But really, it looks more like an advancing avalanche than a cresting surf wave. That's more the that's a more accurate visual is this advancing water avalanche that just keeps pushing inland pushing inland. And as we saw in the in the in the earlier video of the specifically from the, you know, the tsunami rolling in onto the main island of Tonga, as the first wave of a tsunami rolls in more waves roll in behind it, there's a relentlessness to tsunamis, they don't always look excessively violent. They're not always super fast, or they visually they don't look super fast as they are pushing into a city. But the power of this water is clear, it just keeps pushing with more waves rolling up behind it. So the defining visual of most tsunamis is floating debris. So as the water pushes in into land, it's picking things up like cars or shipping containers. If it goes over a port, houses get picked up by the water and they get carried further and further inland, as the water continues to push. And these objects, they smash into each other, they smash into other things, they knock up other things off the ground and pull things off of their foundations and get them into the flood. And you know, I've seen several videos filmed from high up in like condos or apartment buildings or hotels, that's high ground in some of these beachfront spots. And from Cracking into everything that managed to stay that vantage point, filming down into the streets. You know what standing in the initial push, and pulling people that have you've got our boats and cars and mailboxes furniture floating been holding on for dear life, pulling them out to sea that's I down the streets which have been turned into these like churning think one of the greatest dangers in these major tsunamis. So that's that's the visual of tsunamis that I've seen. It's canals. And then sadly, before it gets better, it gets worse the it's the wall of water that pushes in, pushes in, pushes in because when the push is finally done, and the water begins to relentlessly and then recedes again. So not this cresting recede, all of that stuff is dragged back across the land massive surf wave, but the wall of water that's, I think, a more toward the ocean or the bay. accurate visual.

Christine Malec:

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Comparing Hunga Tonga to St Vincent
Satellite Images
Visualizations
Tsunamis