Edward Plumb
Well, good morning, everyone, and thank you for attending today's ACCAP webinar. We'll go ahead and get started here in a minute or so. We'll let a few more people trickle in. Hi there, for those of you just joining, we're gonna give another, Minute to let a few more people pop into the webinar here, and then we'll go ahead and get started. Okay, well, good morning, everyone, and welcome to this month's ACCAP webinar, From Landslide to Tsunami, Tracy Arm and Alaska's Growing Landslide Threat. Today's event is being hosted by the Alaska Center for Climate Assessment and Preparedness. We are also known as ACCAP. And we're located in the International Arctic Research Center on the University of Alaska Fairbanks Troth Yeddha Campus. ACCAP is part of the Regional Integrated Sciences and Assessments program, which is funded by the NOAA Climate Program Office.

For nearly 20 years now, ACCAP has worked with communities, tribal organizations, various agencies, researchers, and other partners across Alaska to provide weather and climate information that supports preparedness, resilience, and adaptation to a changing environment. So. Thank you all for joining today, we really appreciate it. And, so, just over a year ago, back on August 10th, in 2025, a mountainside collapsed into Tracy Arm in southeast Alaska. Generating a powerful tsunami that surged more than a thousand feet up the opposite side of the fjord. Meanwhile, just 12 hours earlier, cruise ships had been operating in that same area. This is an incredible event, but it's also part of a much bigger story here in Alaska. As glaciers retreat and environmental conditions change. Landslides in Alaska's steep coastal terrain. Are becoming an increasingly important hazard, particularly when they have the potential to generate tsunamis.

So today's webinar will take a closer look at what happened in Tracy Arm, and what scientists are learning from the event. We'll also look at, like, the broader landslide threat across Alaska, how these hazards are being monitored, and what they may mean for communities, mariners, and visitors.

But before we get started, I'd like to cover a few webinar logistics. You're, you have all been muted, and your video's been turned off. There will be a 10-minute or so Q&A after the presentation, and at that time, you'll be able to unmute yourself And turn on your video if you want to ask questions directly to the speaker. Otherwise, feel free to drop questions into the chat as the presentation's going on. I will try to answer a question if I have the answer to it. If not. I think there are many of our speakers' colleagues on the, watching the presentation today, and they are more than welcome to answer some questions if they know the answers.

The presentation of this webinar is being recorded and will be on our website later today. I will also send out an email, with the webinar link, for the recording. Later today, or early this evening.

Additionally, you're going to be prompted for a brief survey at the end of the webinar. If you're using the Zoom in a browser, please hit Leave Meeting rather than closing the browser tab in order to get prompted for the survey. We really appreciate you taking just a few moments to answer 3 to 4 short questions.

Well, with that, for those of you who don't know me, my name's Ed Plumb, and I am the Weather and Flood Hazard Specialist here at ACCAP. I'm pleased to introduce today's speaker, Mike West. Mike is the state seismologist for Alaska, the director of the Alaska Earthquake Center, and a research professor at the University of Alaska Fairbanks Geophysical Institute. Mike's research focuses on how seismology can be used not only to understand earthquakes. But also to track other environmental phenomena and provide information that can support hazard decision making. The statewide seismic network, operated by Mike and his team at the Alaska Earthquake Center have also become a really important part of Alaska's developing landslide monitoring capabilities. Mike will walk us through the Tracy Arm event and help put into the larger context of landslide hazards across Alaska, including what we're learning about where these events occur.

How we can detect and monitor them, and what they may mean for people living, working, and recreating in these areas. We're really pleased to have you, Mike, with us today. And looking forward to this fascinating and talk and increasingly important hazard here in Alaska. So, with that, Mike, I'm going to turn it over to you.

Michael West
Thanks, Ed. With that introduction, I don't really have a whole, a lot of preparatory, text, other than to say that, it should go without saying, in a talk of this scale, like. I am representing the work of dozens and dozens of people. I didn't even list them on the title slide, because I know how many people I would leave out. I'll try to give credit through the talk. I will probably miss, some, but just suffice to say, this is, we're drawn from a whole lot of people. The facts I'll present today are theirs, and mine, but the opinions, are definitely mine, and I welcome feedback on Any of those. So, let's start here. And let me find the right buttons. Am I coming okay, coming over okay, volume-wise?

Edward Plumb
Yeah, you're good on my end, Mike.

Michael West
Having a little navigation issue here. Do you see the Hans Explorer on the screen?

Edward Plumb
Yes.

Michael West
I have not laid eyes on this boat in person, but I would sure like to. I think the stats at the bottom lay out their market pretty well. 15 crew, 12 guests, I'm hoping someday they'll land a retirement gig or something. On this, boat. But it tours around the world, and is specifically designed for icy environments. These are screenshots off the website of the Explorer. But, last summer, on the 10th of August, and those surrounding days. They happened to be in Alaska doing a fjord tour around Southeast, and on the evening of August 9th. So this photograph was taken from the deck, the rear deck of the Explorer, around 5pm, on August 9th, they were up at the end of Tracy Arm. This is South Sawyer Glacier in the distance there, and they were there doing what, doing what we do in fjords like this, looking for, calving glaciers, and the ice and the water there is a pretty clear indicator of how active, South Sawyer is, though I'm told that that particular evening.

It was, eerily absent of calving events.

Anyway, they hung out for a couple of hours. This is a video shot from the back deck at the same time, and if you follow this, it's gonna pan across, the front of the glacier. So here's the right side of the glacier. That's the glacier front. And on the left side of the glacier, the north side of the fjord, is this rather ominous-looking, mountainside. So, we're gonna come back to that.

Anyway, they, they watched for a couple of hours. Oops, sorry, I'm still, Here we go. Damn. Then they motored out, there. So, they last about 5PM, and according to ShipTrack, Records, believe they were. They're the last individuals, In this fjord, and 12 hours later, something like 5.30 in the morning, reports of, violent seas and tsunami waves started popping up around the whole, this whole area in South Central. So, there are many accounts, you've probably read some. In stories, but one that certainly, catches many of our attention is the group of kayakers who were camped out. This is a few tens of miles away, outside of Tracy Arm. The quote's there. This photo's a little hard to dissect, but if you look at their tent on the left. And then look at all the grasses directly in front of the photo. You see how they're matted down? That is where water came.

The water, which rose very, very, very quickly, and literally came by great coincidence, like, right to the height of their tent, and it brought up, washed this stuff, up onto, shore before, before retreating. Washed away their boats, washed away most of their gear. Fortunately, they had their radio, their marine radio, still, put out a distress call. And, this is a, A ship, a boat in the area that happened to hear their distress call, but also, turned on a time-lapse camera That they happen to have. So, they missed, we're not seeing the primary swell of water come and go, but I'll play a short little clip of time-lapse video, video here. This is the, this is the aftermath. This is the gentle sloshing, if you will. That came after the main wave rolled through here. So, it's a little hard, but if you look at that light-colored shoreline, you'll see the water start to recede, and you see that dark line right along the water.

And in this video, it only drops maybe 2 feet or so. But if you drop 2 feet of water, in a matter of a couple of minutes, there are tremendous currents that are needed to move that kind of water. So this was violent, even after the main swell of water had come through.

Anyway, This ship, there it is, this is the Blackwood, photo of it down on the, right, taken, I believe that was taken that morning, August 10th, drone footage, and they actually heard the distress call, went and picked up the kayakers, happy reunion there on the back of the deck, definitely, in the grand scheme of things, terrible situation, avoided. But, That's a quick little, just one taste of many of the different things that were happening this morning as, different boats, different groups of people, in August were, you know, touring in the area, and kind of just noting, honestly, a rogue wave out of nowhere, with no real obvious source. So, that kind of brings us back to the title slide here, and specifically a question of why myself and my colleagues, I'm a seismologist, I'm an earthquake person, how we got involved or have been involved in this, at all.

So. A little background, I direct the Alaska Earthquake Center, and among the things that we do, one of our primary assets is a network of stations, all around the state that we operate. The red symbols on this map, our seismic monitoring stations that we operate. The yellow ones are partners in Canada and elsewhere that we happily use their data. And at each one of these sites, you will find, seismic monitoring instrumentation. So there's not actually a lot to see, because the interesting stuff is buried underground. Do you see my cursor or not?

Edward Plumb
Yeah, I see it, Mike.

Michael West
Okay, I will use the cursor. But the interesting part of the seismic monitoring is buried underground, because its whole purpose is to record the vibrations of the ground. But these are scattered all around the state, supporting our primary mission. Which is earthquake monitoring.

So, this is what the year 2025, looked to us from the perspective of earthquakes. These are earthquakes at different depths all around the state, and we have a whole earthquake monitoring mission.

However, those instruments Seismic stations really pick up anything that shakes the ground. It might be an earthquake, it might be a mine blast, it might be a moose walking by, it might be the wind blowing in the trees. It's not really a very sophisticated instrument, it just measures anything that moves the ground. And on the morning, of August 10th. The ground moved. So here's a record. This is a, this is 10 minutes of seismic data, recorded in Juneau. On the morning of the 10th, about 5.30 in the morning. And what you're seeing is a record, a graph, of the ground as it moved up and down. So this is normal. This is what earthquakes do, whether they are in Alaska, or this, you know, this weekend's magnitude 7.7 in Indonesia. Those waves ripple across Alaska and are picked up by instrumentation like this.

So, this is a record in Juneau. That same morning, at the same time, here's what was being recorded in Sitka. Skagway, Whitehorse, Yakutat, and on and on, out to Cordova, all the way out in Vancouver, British Columbia, Kodiak Island, you see that these signals are getting a little bit later and later in time as you go further and further away. And in fact, if we take all of those seismic stations, put them all together, we get this rather remarkable record that, to a seismologist, has a very, very distinct signature. I'm not going to go through this, but basically, it doesn't look anything like an earthquake. This is a pretty clear signature of a landslide. And if you take that data, you can kind of back-project it to where it came from and when it happened in time. And when we did that. We end up with, you know, pointing back to somewhere here in southeast Alaska.

We'll zoom in on this, and that is the focal point, if you will, from which those data that we were just looking at appear to have emanated. So, Zooming in on that, here's our kind of landscape for the day. There are two fjords here in southeast Alaska that I'd call out. One is Endicott Arm, the other is Tracy Arm. Actually, the early chatter we heard in the morning, that morning, was mostly from vessels that were actually in Endicott Arm at the time of this, so our attention was originally down in that area. The kayakers from a previous, a few photos ago were camped out there on Harbor Island. The boat, the Blackwood, which I pointed out, was in a harbor just north of there, so they were close by, that's why they were able to respond. That seismic location, those waves on the previous slide, appeared to point back to a location that we pinned down to about where this orange arrow is, and based on that, it seemed likely to us that actually something inside of Tracy Arm was probably the more likely candidate, source region for this.

But I want to stress, when these events are unfolding, in hindsight, everything's so crystal clear. But on a morning like that, when you're getting, you're getting random messages from people, you're trying to make sense of data, there's a certain fog of, a fog that, of things that just aren't really clear, and you're trying to figure them out. It was actually complicated that day, because it really was a lousy weather day. It really was foggy, and there wasn't a whole lot of visual observation coming in to help pin things down.

The Coast Guard did go out and fly, in part premised on this location, that we provided, and, oops. Am I? Oh, yeah, sorry, this is video from that Coast Guard flight. Again, kind of lousy. This is the end of South Sawyer Glacier. As you approach the terminus, That is all, Half of the, All that dirt and air. Raw footage, so, Okay, so there's the end of the terminus of the glacier, covered in rock. Also note that mountainside. Kind of fresh. The light color, We'll come back, we'll have, better folks. And then the water is, Rankin. I'm, This looks to me like a slurry. Again, all crystal clear signs. And looking down the field, Yeah, as far as you can Just this. Rock, water, ice, Mixture, if you will.

So, big ground truth to this, to the location there in red, which is precisely at the terminus of South Sawyer Glacier. It is exactly right where the terminus, is. So, based on that seismic location, we also can derive some very, rough estimates of the volume of a landslide. The bigger the landslide is, the bigger those seismic waves, are. And we have a very simple regression for that, but they, we finally settled after months of research and whatnot, the, you know, group consensus is something of about 64 million cubic meters or more, and the or more is because we can't really assess what part of the landslide was underwater. But there's at least 64 million cubic meters exposed up top, and I've played this game for a number of years myself, trying to wrap my head around what a million cubic meters is, or 64 meters. So some of our standard analogies are the volume of an Olympic-sized swimming pool, it's about 20,000 of those.

One that a colleague came up with that I kind of like. This is about 24 pyramids of Giza. And I, when I started putting this talk together, earlier in the summer, we were in full-on World Cup mode, so I'm gonna drag you through my latest, analogy for this. This is the cross-section of the landslide derived from, well, literally the topography before and after the, after the slide. One thing to point out is the y-axis, the vertical scale here. This landslide was a kilometer tall. That's an unbelievably huge amount of mountainside, and if I, if nothing else, that's what I want you to take home from this, is just how big it is. So, we were in World Cup mode, when I put this together, here is a regulation size FIFA World Cup pitch. I think it's 105 or 110 meters in length, and if we overlay that on this landslide, It looks something like that.

So, again, just an enormous amount of rock, which is the reason that it shook the ground in a way that was clear, honestly, it was recorded clearly across the entire hemisphere. The events of this size are sensed that way.

All right, let's do another video. A couple days later, my colleague John Lyons at the USGS was part of a group that was able to fly in much nicer weather, and you were looking here at the top of the landslide, the fresh, light-colored rock being the scar, and I'm gonna pause it for one second And draw your attention to the very top of the head wall. This, head wall up here, which continues to be a source of, well, concern, really, because if you look, it is vertical, or, I don't think it's really overhanging, though the perspective almost looks that way. Whatever you want to call it, it is over steepened. And there are ongoing concerns about landslides in this particular location in Tracy Arm, and much of it is premised on the possibility that the top of this thing did not actually go, or that that might be a precarious block Right now.

Anyway, We'll keep playing this out, And this is a, again, we're a kilometer above the water now, and the scar of this thing extends all the way down to water level. I think we're gonna pivot around here in a moment. See the water. Let's see, I'm gonna bump this ahead a little, Bump it ahead, there we go. So this would be kind of the view from the top. Now you, now you can see the terminus of the glacier, you can see the rock, debris there, and you can see the scar. Of where this slide, detached. Alright.

Moving onward here. Okay, here's a photo from more or less that same location up near the top of the landslide. You see the glacier, but what this photo shows really well is the run-up, as we call it, of water onto the opposite fjord wall. So all of that bare, exposed rock over here. Are places where the rock, ice, water, debris, in a matter of, you know, tens of seconds of the landslide, washed up here and scoured away, you know, the vegetation that had been there. So, I don't have a before and after photo of this, but, you know, there, there was vegetation. Everything in its way was stripped off. So, the vertical height of that, run-up is something just shy of 500 meters, about 480 meters or so, which, again, is, you know, every time you hike a ridgeline or something, it's 500 meters. You know, that's a, That's a heck of a hike, right? Again, just important to kind of put that in perspective, so, Here's kind of an annotated version of that.

You'll see the landslide in the top of this figure outlined in white. We see that the deposits on top of the glacier, and some of where the glacier had been, in red, and then the run-up, the slosh, the fancy term for it, the slosh on the opposite fjord wall.

Maybe a half dozen miles or so, half dozen kilometers down the fjord, is Sawyer Island. This is a photo taken a few years ago. You can see the glacier in the distance. There's some foreshortening in the photo here, but this island sticks out just in the middle of the fjord. And, after, August 10th. Basically, everything on that island was just stripped right away. There's no, there's not even soils left, save for a particularly, tenacious tree, up there at the top. So, This is not a unique event, it's a remarkable one for sure, but it lives a little bit in the shadows of the 1958 Lituya Bay landslide that many of you are probably familiar with. This is a photo. From Lituya Bay in 1958, this landslide in the far, the far wall here. Ran over the mountainside in front of it here, which again, stripped, it leaves a very nice record, a very clear record, of where the water was and where it wasn't, because where the water reached, everything's gone.

A lot of attention has been paid to the height of that run-up. Personally, honestly, I'm not convinced that that is the most important takeaway from an event like this, how high the water sloshed up the hillside. It seems more important to me what tsunami was unleashed across the area. However. You know, if you're into Guinness World Records and stuff, it's hard not to get hung up on the height of the run-up. So, a graphic, that we did associated with the release of Kind of the big summary paper on this landslide looks something like this, just to put things in perspective. The Tracy Arm Run-Up, as I would call it, is just a little bit smaller than Lituya Bay in 1958, but still monstrous. And you're, you take your pick of skyscrapers to put that into perspective.

An extremely talented colleague of mine at the University of Southern California, Pat Lynette, did some quite sophisticated modeling of this, slide, and really did a great job of putting this together in a way to understand. So I'm gonna play a little video here. On the top is just footage from Tracy Arm taken, shot a month later. A month or two later. And on the bottom is a numerical model. It looks like a cartoon, but the important thing, this is a, you know, a quantitatively grounded, sophisticated, numerical model of the slide, and we're watching it now. This is in, this is unfolding in real time. So it's not being sped up or anything. So you can see, as this landslide began to advance down the hillside, remember, we're coming a kilometer from the top down to the water. It impacts the ice, it sets up the beginnings of a wave. And this thing begins to tear across the fjord.

You know, we are only, I don't know. 20 seconds in, 30 seconds in, we are already approaching the other side of the fjord. So here would be the run-up. And again, up top, you see the real, actual, scoured landscape. On the bottom, you see this numerical model. And again, I'd highlight, we're, I don't know what we are, 45 seconds in or something? And that event is over. Now, there's a whole bunch of stuff still to come, but that, that initial landslide and slosh is incredibly fast. I can't fathom what the currents were for the coming hours in this bay, but water is set up, sloshing back and forth in all sorts of directions, and at the same time. In the far distance, you can see the head of the tsunami. You can see that front wave taking off as it speeds down the fjord and out, eventually out of the fjord, out into the surrounding, Waters in Southeast.

So, Why? I think that's a key question. What is it that drove this landslide to happen? Is it just a, Random act of God, what are the controls on this?

So, a few things. We're going to step through a few different observations. One is we're going to take a look at the glacier itself.

So, this is imagery from 2020. The dashed red lines, those are where our landslide will show up a few frames From now. And this is just one of many ways of demonstrating the retreat of this glacier. So the yellow line marks the elevation of the glacier well, 50-some years ago, 50 years ago or so, and it, of course, had retreated. The glacier once extended much further as well. So, the glacier has both retreated, or the terminus has retreated. And it's just a much, much thinner version. Of what it once was.

So let's step forward to June of 2025. Okay, a little bit of retreat, but it kind of hovered in this place for several years. But this is June, late June. We're gonna toggle here forward just a little bit to July. 1, 2, 3, go. Maybe small little change, tiny bit of a retreat, but then between July 18th and into early August, we lost another big piece there. I'll sort of toggle. And, you know, that's not super overwhelming, it's not a huge amount of a retreat, but this was clearly a time period where that northern end was like, okay, now's the time, now we're gonna let go and pull back here. And what it's doing, it is sweeping across the base of this glacier, or sorry, of the eventual landslide. Forgive me. So this is a couple days before the slide, and then, of course, after, you know, the, presumably the landslide itself dislodged much of the end of the glacier.

So, the observation is that this landslide occurred not kinda, sort of, but exactly as the, geologically speaking, as the ice was retreating passed it.

And this is something that we have now observed at quite a number of places. So, with, Apologies to a colleague of mine, Lauren Schaefer. This is a hacked version of a very nice graphic that she has, but here is a cross-section of a generic fjord that has glacier ice in the bottom. And when you come in and, you know, after thousands of years, you take away the glacier ice. Boom. You are left with these over-steepened fjord walls. And I'll tell you, we actually don't understand. Conceptually, it makes sense, like, oh, there was ice there, and now there's not, and so the rocks are unstable. It's easy to say. It's actually kind of hard to produce a model that's really compelling. I personally find it hard to understand how a giant rocky mountainside gives a rats about whether or not there's a little bit of ice down at the bottom. But it appears to matter.

A word that we are throwing around a lot these days is we're using the word debuttressing, sort of suggesting that perhaps the ice per, perhaps with sort of holding up the rock, or there may actually be other mechanisms tied to the flow of water, or water pressure, or whatnot. This is very active research right now, that maybe we'll have better answers for in a few years. But the observational fact Is that when we remove ice from fjords, we see a much higher rate of these landslides. So, I want to walk through a few other examples recently.

Tracy Arm, we've looked at that, so we have that on the map here. If we rewind to 2015, a similarly, huge landslide occurred down near Icy Bay. The photo on the left, doesn't really do justice to the run-up. You can see the, this, where the tsunami ran up on the other side, that is 190 meters above sea level. So, again, a huge elevation for water to splash, if you will, up. But really, it's the same basic geometry. You have a landslide there, across the bay, across the fjord. It is occurring right at the end of the glacier, as the glacier is retreating past. This is a, it's a, It's kind of a common geometry.

Surprise Cove. This is one a couple of years ago that holds a particular meaning for me. I was fortunate a couple of years ago to lead a, to coordinate a field trip for about 300 scientists in Prince William Sound on a gorgeous bluebird late April day, chartered the, we chartered a cruise ship. This is a stock photo, but this is what it looked like the day we were on the Klondike Express. Phillips Cruises, many of you have probably gone out with them at some point. But we took 300 and some scientists who were in state for a professional meeting out on a grand tour of 1964, earthquake geology, and we went to look at several major landslides. Barry Arm, you might have heard of, just really a treasure trove of really easy, big, geo hazard kinds of things. But we also did some glacier calving you know, tourism, because how can you not? Now, we went into Surprise Cove.

This is Surprise Cove. This is a photo, these are photos taken that day on the, from the back of the deck. We were there to watch calving, from the glacier, and again, I can't fathom how many Instagram posts were made that day. It was a gorgeous bluebird day, magnificent spot. Didn't really think anything about taking the group there. And, Turns out, 4 months later, the mountainside on the right here, so just the right side of this glacier, went through one of these very same kinds of collapses. There was a period of, This glacier had retreated rather rapidly, and let's see, I think we have, here you go. This is taken 4 months later, this aerial photo, showing the landslide, the deposits onto the ice. It appears that only a modest portion of this landslide made it into the water.

However, it was big enough that it was picked up on tide gauges 20 kilometers away, so the impact on the water, the water wave. We don't have a good understanding, to my knowledge, of how, what that actually looked like here in the bay. There wasn't some giant run-up on the other side. But, you know, yet another example of one of these. In fact, this is a picture of two of my close colleagues, Ezgi Karasozen, who works here at the Earthquake Center. I am showing a lot of her work today. In this presentation, Revathi Parameswaran, who I work with here at the GI. Here they are, you know, taking, again, it's a gorgeous day, taking pictures, and drawn in the back there is the landslide Source, 4 months later. So, we'll add that one to the list here, and just for fun, the last arrow here just across the border in Canada on Mount Logan. This is a significant landslide last week that, I haven't introduced this yet, but we run a detection system for these large landslides.

On the left. You'll see those seismograms, not unlike the image we had a little while back. All this, the different recordings from each one of these blue stations across the area, and again, kind of the telltale signature, of one of these landslides. Again, we had some rough volume estimates on this, but what's really helpful is when we can pin these things down, either through human observations, or overflights, or satellite imagery. So, little satellite imagery of here, August, a fourth on the left-hand side, this is before the landslide, and August 7th, a couple days later, there it is. These things appear to be popping off with quite a bit of regularity, you know, here in sort of the August time of year. So, again, just for scale, I mean, that's 3 kilometers. That's a huge distance for rock and debris, to flow, not just down the mountainside, but out across the ice.

We are now, now that we have some abilities to, detect these things in real time. Our system's probably, picking up a couple dozen of these every summer. Only some of those are on the coastline, so the tsunami potential, there is no tsunami hazard associated with this particular landslide, because it's high on a mountain, but it comes with other hazards. But what we are seeing is a very real increase in this kind of event, and one that I would argue we haven't really come to terms with yet. So that prompts the question, are we all doomed? Is there anything we can do about this? Do we just, I don't know, sit back and let it go. Ow. Let's go forward. I will point out that at least as of a little while ago, 7 cruise lines had decided that this year they would not enter Tracy Arm any longer, and it is not the only location in Alaska that is now being avoided by these, ships.

Tools that we have to work with going forward. We're, again, these are very much evolving things, but first. We can identify slopes that appear to be unstable. It's not perfect, but this is a map of Prince William Sound from a recent USGS publication identifying specific slopes that have shown some movement, trackable, you know, at the centimeter scale through satellite, interferometric methods and things like this. This isn't necessarily where landslides are gonna fail, but if you gotta guess, this is a pretty good starting point. These are slopes that are already showing some instability. So that's a base data layer that we have to work with. Some places. Appear to be more landslide-y than others. Weather, precipitation appear to play a significant role in this. You're looking at a plot here of cumulative rainfall, in the two months or so prior to the Tracy Arm Landslide.

I'll point out that this isn't, this wasn't really record-breaking precipitation in any way. It's run-of-the-mill, late-season. Precipitation levels, but still, you know, Tracy Arm and many other landslides, we have found occur, you know, after some degree of considerable precipitation. It rarely happens when it's, when it's been dry for weeks. So we have that information to work with, precipitation.

We already talked about Glacier Retreat. We have enough information now to have a good sense that when a glacier is in a period of particularly rapid retreat. Right? It is commonplace for glaciers to kind of sit in one region, and maybe then, over the course of a year or a couple of years, retreat rapidly. That's something we should be keeping an eye on. That's a, that should put up, Maybe not alarm bells, but at least a caution flag on particular locations.

And then one I'm not going to get into too much today, though this actually happens to be my own, work, and a lot closer to what I and our group works on. These are seism, this is a, these are seismograms here, or a seismogram for the 14 hours preceding the Tracy Arm Landslide. You can read this like a book. So, you, Yeah, over a half a day or so. And what you see here is a remarkable set of seismic precursors. These were coming from Tracy Arm. That landslide was sending out, bing! Bing! Bing, bing, bing! Not only these little events, but increasing in time that were highly suggestive of some kind of, you know, a culminating event. Now. A lot of landslides, maybe even most landslides, don't do this. But we have come to learn that when we do see this, we better pay real careful, attention. So this is, kind of a version of what we were just looking at.

The same seismic data on the bottom, except now in a single long seismogram. This is a spectral representation up top, and if we speed it up about a thousand times, you can listen, do these little pops and creaks, I hope you can hear it, but, Oh, I'm not hearing anything.

Edward Plumb
Yeah, I can hear it, Mike.

Michael West
Good.

Edward Plumb
Kinda sounds like static, almost.

Michael West
And then the Landslide. Right there. Almost like popcorn to me. But again, the take-home point is faster and faster and faster and faster, pointing towards something. So when that happens, it's a huge piece of information for us. So, What you, what I've thrown out here are just a smattering of observations that the Alaska Landslide community is not unique to Alaska, but certainly a vibrant effort going on, trying to figure out how to piece all of those together to figure out how to, How to monitor Landslide activity over, you know, a huge area. Whether it's, Southeast, or Prince William Sound, or in Cook Inlet, all across these areas of these big, bedrock-seated landslides are happening.

And actually, a caveat, I should have said this much earlier in the talk. There is an entirely separate class of landslides that are shallow-seated. You can think of them more as sloughing, loose debris off the mountainside that have, actually been, by far, our more damaging events in Alaska in recent years, whether it's, Sitka, Ketchikan, Wrangell, the deadly landslides that we have experienced in recent years are actually far, far smaller than what we're talking about today. That doesn't matter when it comes to human impact. They're the ones that are, that, to date, have actually caused us a real economic and human toll. We're kind of focused here in this talk on this class of, I don't want to brand this, the, they're not mega landslides, these truly massive ones that, so far, we have largely avoided, significant human impact in the recent years.

Anyway, how we put all these things together. I'm gonna throw out just one paradigm, but it kind of shows you where, how we're starting to think about piecing all these different pieces of data together. I'm gonna argue, we're in the opinion part of the talk here now. You know, I'm gonna argue that if we know, if we have some set of unstable slopes, and we know we're in a period of, of elevated weather or elevated precipitation or something, it's at least conceivable To have, you know, to issue cautions, if you will, around certain geographic locations. Not this slide here, but rather, you know, the northeast corner of Prince William Sound is an area where, realistically, it's raining, it's August, There's higher risk, that's a fact.

We have other indicators, like retreating glaciers or seismic precursors, which might help point to very specific locations, which, again, you say, huh, in this area of elevated precipitation and unstable slopes. There's a glacier that's retreating really fast. Maybe we want to put a little watch flag, on that. If we see seismic precursors that we can actually identify as coming from some particular, region, I think we definitely want to put a little warning flag on that and say that, our eyes are watching this particular slope right now.

And then, of course, we have a variety of tools for when a landslide event is in progress. And remember, the tsunami event might actually take an hour or more to unfold across the region. We then have the ability to say, hey, you know, yellow, orange, red, like, an event is in progress. So, this does not actually exist right now, but this is the space that people from a whole bunch of different disciplines are coming together, to try to figure out. It is, I would call it a scientifically exciting time, because I think many of us feel like we're in the early stages of what we hope will be important at some point.

So, which brings me to, let me wrap up here. This is just me riffing here, but I'm trying to find the points of intersection, particularly with this audience, and a few take-home points. Look.

Climate appears to be driving the increase in landslides, both from retreating glaciers, thawing permafrost. There's definitely a climate angle to this that many people on this call actually are working on.

Weather appears to be contributing to the hazard. If you are going to place bets on landslides, go on Kalshi or Poly Market, first, don't do that, not cool. But if you are going to, you know, pick rainy times and places. That's just, this is, this is when they are most likely to happen.

But similarly, weather's probably a really important monitoring tool. As we try and figure out this hazard. I think, I don't know if Gabe Wolken's on, but certainly, familiar to many of you, has put a lot of time toward this, and other colleagues. This is clearly a place where better weather information is going to help landslide forecasting.

And then, of course, tsunamis are a form of coastal flooding, and I think there are folks in your audience who are coastal flooding related. So, one final example here. And I'm probably gonna get in trouble. It's probably not cool with weather and climate people to show screenshots from Windy, but they do have their graphics down, so allow me that, that violation. But this is a rainfall accumulation forecast. Again, just, I just pulled it off their website yesterday, for the next 4 days. And I don't know if any of this is right or accurate, I assume it's not very well tuned to the region or something, but this style of information Being able to look forward and say, you know what? Actually, serious rainfall event here, not so much worried over there. I am certain that that is going to be an important part of whatever monitoring system comes together.

Around these things.

So, let me wrap up here. I'm gonna go back to the same animation to take us out, but my colleague Pat Lynette, who created this, also actually turned it into a video game. I'll have a QR code on the next slide, you can actually go play it if you want, and you can put yourself in the place of this landslide. And, put yourself on a boat, in this case, a jet ski, that will become visible to you in a moment. And the whole goal is to see if you can outrun the tsunami. And I don't want to spoil the game for you, but you can't. One of the things that was clear from the forward modeling. Of this, landslide is that there actually was a cresting wave of something like 100 meters tall. This wave here. As it swept out, and down the fjord, so, I think the jet ski here is going 70 miles per hour, but it's about to get overtaken, and Yeah, you can't win.

But, Anyway, I think a nice example of trying to make connections and drive this home for people.

Okay, that's it. I've taken up plenty of your time. Thank you, I hope I didn't cut too much into our, question time, but I'm happy to take questions by email, or reach out to me any other way.

Edward Plumb
Thank you so much, Mike. Really appreciate it, and I'll include that QR code in the email I send out later today.

There's a number of questions in the chat, which I couldn't answer, and there were a few answers, but we still have a lot of questions there. But first, if there's anybody who wants to ask a question directly to Mike, I have a, Click the buttons to allow you to unmute yourself and turn on your video. Otherwise, I will jump through these questions in the chat, and if we don't get to them all before the top of the hour, Mike, I'll provide them to you, and I can put them in the email, too, if you want to get an answer to them.

Michael West
I'll do my best.

Edward Plumb
Okay.

Any questions from the audience directly? To Mike? Feel free to unmute yourself. Okay, bye.

Jeffrey Phillippe
Yeah, I have a question.

Edward Plumb
Go ahead.

Jeffrey Phillippe
you do. Yeah, hi, I really appreciate this talk. The seismic precursors, you know, you can get on the Alaska Earthquake Information website and see, you know, seismic activity less than, you know, 3.0, and is that something that you recommend people to check out? You know, if you're going up into these fjords, would you recommend looking at this site beforehand and looking for those microtremors, or however you call it, as a reasonable indicator that something is Potentially gonna happen, and a no-go.

Michael West
Yeah, it's a really good question. The short answer is, while I would love for you to come spend time on our website and explore all that is there, I do not see a resource at this time that is useful for decision making. Around landslides. Our mission is still primarily driven by, earthquake activity in this state, and these, I showed these precursors, on these very compelling precursors on the slide. What I perhaps did not drive home adequately is that we did not see those. We did not recognize them for what they were until after the event. We have a long way to go in looking for that type of activity, which, without going into the details, is just really different than what, earthquake stuff looks like. So, no, we don't have something At this point, that would be a useful resource that way.

Jeffrey Phillippe
Thanks.

Edward Plumb
Okay, I'm gonna, The next few minutes, just to ask a few of these questions from the chat.

Michael West
Fire away.

Edward Plumb
Okay. And then there's more questions coming in, too. Okay, so I'm gonna start back at the beginning. I think somebody tried to answer this, though, but, They were asking, where's the grounding line for the glacier? And somebody had commented, likely the entire glacier is grounded, but then somebody else commented that their experience with South Sawyer was, it's likely not totally grounded right at the face of the glacier, so I'm not sure if you, Have a confirmed answer to that, or not?

Michael West
The short answer is, I do not.

Edward Plumb
Okay.

The next question, is there an effort to map out areas of landslide risk and related tsunami risk?

Michael West
Well, I showed one small screenshot from an effort to map out slopes that were moving. This was from a USGS report. That's a slightly different thing. There are multiple inventories underway right now to identify, let's call it slopes of concern. It's not exactly 100% sure how to do that, right? Because they're, they haven't happened yet. So, yeah, there's a lot of really good efforts. I would personally focus on the ones that come out in you know, peer-reviewed papers, and whatnot, but I will then point out that, like. Tracy Arm wasn't on, those lists, at least not the list that I'm aware of. The Surprise Cove landslide that I mentioned, that wasn't on one of those lists, so that's good. I don't mean to undermine them at all. This is a really important effort that's happening right now to inventory the slopes of concern. So there are lists out there.

Edward Plumb
Okay, and then I'm going to jump ahead a question, which kind of ties into that, but Is there a tsunami warning system in Whittier. I think specifically, I know Barry Arm in Prince William Sound impact Whittier. If that slope released so, kind of tying into the alerting system, are you aware of a, Warning system specific for Barry Arm.

Michael West
So, I didn't call out the tsunami Warning Program operated by the National Weather Service today. I probably should have. They are an important partner in this very interagency effort to come to terms with landslide tsunamis. It is a hard puzzle, right? Because the timeframes are very short. It is different than, an earthquake in Japan that sets up a wave that then rolls across the Pacific Ocean for 6 hours. The timeframes are really short, and the triggers, that is identifying the landslide itself as it happens, is something that we just started doing a few years ago, and look, it's not perfect yet, at all. So they've got a hard challenge. Specific to Barry Arm, they do operate, the National Tsunami Warning Center out of Palmer is operating a few dedicated tide gauges. And I certainly don't want to speak for them, but they are, they have what I would call experimental procedures in place for alerting.

I mean, at the end of the day, a tide gauge Is your most definitive information about whether or not there is actually a tsunami rolling out across the area.

Edward Plumb
Okay, great. Thank, thank you, Mike. Yeah, I was, I was aware there was, yeah, a tsunami, you know, monitoring station, in Prince William Sound, but thanks for answering that. And we're at the top of the hour. I will share with you a few of the last questions from the chat. To you, Mike, and then I don't know if you can, take a shot at answering them, and I could provide, in the email I send out with the links and the link to the recording, but Thank you, everyone, for attending today. We really appreciate it. You got a lot of kudos in the, chat there, Mike. I'm not sure if you can see it or not, but it looks like.

Michael West
Correct.

Edward Plumb
enjoyed the presentation, and people are sharing different links for different resources, and I'll capture all those and send them out as well.

Michael West
Okay. Appreciate your time, thanks.

Edward Plumb
Okay, have a good afternoon, everyone. Thanks again.