Have storms caused waves of mud to crash down the Appalachian Mountains before?
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- เผยแพร่เมื่อ 6 ม.ค. 2025
- Helene was an incredible storm and is now the "storm of record" in many parts of the southern Appalachians. Has anything like it ever happened before? This video shows how history was repeated in some parts of Watauga County, North Carolina, and how different land use in the past led to some incredible outcomes in 1940.
I find your videos so interesting. That's crazy that all that land that's forested now wasn't in 1940.
There are a whole lot more trees in Appalachia today compared to 1940 and before
Yeah most of the eastern US was deforested except in areas where they couldn't readily reach the trees for lumber charcoal and "pot ash" and once land is/was cleared they naturally agriculturally exploited the land until the soil became depleted from tilling for example. Trees were heavily used for industry rather than primarily relying on fossil fuels wood was one of the main products along with numerous crops used as sources of fibers, dyes and other natural products in addition to food.
The civil war was a big event for deforestation in northern VA in one of the county parks there is a point where you can basically see the forest edge left because that area was too steep for their equipment to access. It was interesting to see the old leaning oaks still visibly leaning where they had reached out into the light. Notably unlike many of those overzealous tree cutters who attack try and convince land owners to pay them to remove leaning trees at the edge of woods which they claim will potentially fall many of those trees are still standing tall over a century later. Trees that lean naturally and have stood for years are generally not a risk unless other signs point to them because plants can develop supporting counter balancing and or anchoring tissues to maintain stability.
I should note that some tree disturbance is natural, in fact oaks and hickories generally require natural disturbance from fire in order to maintain their presence in a forest landscape. Without fire these trees tend to get either slowly overtaken by either slow growing climax species growing in their shadows such as beech, hemlock(RIP) and holly or get overtaken by faster growing colonizers filling in the gaps in the canopy. In the forests of Eastern North America the typical natural fire cycle is generally around 50 years.
Though the scale of deforestation seen in the pre WW2 industrial era was at a whole other level with devastating ecological impacts such as the extinction of old growth forest specialists. Sadly a lot of the regrowth domestically has come at the expense of neocolonial economics driving deforestation in what were or still are former colonies.
makes one wonder how much worse the Helene flooding would have been if it were still deforested
Today, we produce far more food on far less land.
@@Dragrath1Where do you get this information? Trees in NC grow like mad. You have to cut them to be able to live among them. If trees aren't cut or prevented from growing they will completely overtake a property in a matter of a very few years, which is what this property in Watauga looks like. I talked with a forestry person about the constant complaint of cutting trees and he said that NC was not like the plains states because it grows trees so easily here. I have to constantly pull up baby trees in my wooded lot or the pines, poplars, maples and sweet gums would devour my house. You talk of deforestation from the civil war as though the land wouldn't have produced many generations of trees in the over 150 years since. Even Japanese Maples on my property that were purchased and added, produce hundreds of little trees all year long. There's a reason logging is done a lot in this state. If the topsoil is not stripped with the logging, the area will produce a new forest in a few short years.
If the trees get crowded and weak and they sit on clay soil with a thin layer of topsoil between, that seems more likely to be part of the problem, but I'm not the expert, just a long time observer living among the trees.
That is amazing to see the number of landslides that happened in 1940. I didn’t know that the southern Appalachian mountains were completely cleared only 85 years ago. The northern Appalachian mountains were cleared earlier for firewood but the trees were allowed to grow back more than a century ago in New England.
it would be worthwhile to just cruise old photos and see just where and how tree cover has changed. generally, though, what you saw here is widespread. folks farmed mountain ridges at elevations and exposures that are hard to believe. it's all forgotten now...quite interesting.
I can recall southern WV being nearly cleared in the 70s. Lots of pictures from the 20s-40s show those slopes looking as clear as these. There were flash floods almost yearly in the hollow where I lived in the late 70s. I looked at it with the liar after you showed how and I can see why.
Also looked like several scars of even older events in the hollow where you started the video, as though this happens regularly there in a geologic scale.
@@backburner3590 yep, Appalachian slopes are definitely on the move at the shorter (10s of thousands of years, at least) time scale, anywhere you go. No one knows how old the oldest stuff you can see is, but it's definitely thousands of years. Folks are curious if things were more active during the Ice Ages. Southern Appalachia wasn't glaciated, but the climate would have been pretty ugly.
@TheGeoModels that makes sense. The Cove at War, WV is interesting to look at on the lidar. It's in a steep bend in the Dry Fork river and almost looks like the was a large slide in the long past. Just up river is a feature the locals call "the breakthrough" at Rift, near Berwind, WV. I don't know the accuracy of the story, but old timers used to tell me that the event occurred during a large flood in 1916 (ish. Some said 17 or 18) where the river punched through a 100-foot+ vertical rock face and carved a new path overnight. You can still see the old riverbed plainly beside of the road (which still follows the old course), but the railroad goes through the new gap. There is very little weathering on the fallen stone slabs in the current riverbed.
By profession I am an electrical engineer, specifically power systems. But I find your videos very informative and interesting. I am an enginerd and love the way you explain the science behind these events.
Thanks. I'm sort of a picture-minded kind of guy so I'm always looking for a diagram to cook up.
Went to Boone this past weekend and spent time riding down the Watauga river and spent some time in Foscoe! Truly amazing to see how much power these rivers and streams can produce!
Finding this channel was one of the few good things to come out of the storm. Great work as always. Learn something new every time.
First! We love your videos they're so informative and help me visualize the enviroment around me every day, Thank you!
Thanks!
Thank you. You have explained the geological dynamics of what happened to Western NC. It makes me wish I had taken geology in college.
well i'll give you some main ideas here as much as I can! it's interesting to think about. most of what I work with is material movement instead of rock ages, fossils, etc. it's a wide ranging discipline.
@@TheGeoModels Yes something that is important to us/life saving NOW to us. Sadly the people that were at that presentation didn't take it seriously😢.
I didn't know landslides happened in NC, I thought it was just a California thing🤔.
@@CrackerFL there's a place in california that actually looks exactly like the 1940 pics from this video. You can get a slide anywhere with slopes. There was a huge one in 1948 in florida, of all places, up in the panhandle. happened after a quick 12 inches of rain. I think it was locally well known for a while.
@@TheGeoModelsafter a noteworthy disturbance post-Helene, I've been obsessively learning about the geology of my property in Henderson county. Your content has been invaluable! I also read a lot of FEMA, USGS, and NRCS documents on the phenomenon, even seeking information on insurance coverage for damages, though not applicable in our situation. Somewhere along the way to discover that the potential exists in each of the 50 states, the only insurance against damages is a fairly rare specialty policy. Homeowners, flood, or earthquake policies don't. Per FEMA, there is no coverage for mudflow. The USGS has been warning of the risks since at least the 50s but it would appear that none of the other government entities were listening.
I have 1951 imagery from our land indicating it was fully wooded and it's remained undisturbed and unmanaged since with the exception of the driveway (in the valley) and a leveled site for the cabin. There has been disturbance and considerably clearing off trees above us and I've witnessed evidence of numerous slides, most of which is still in place. I can say that our trees saved those below us but hiking has definitely become rough with all of the downed trees and Rhododendrons! It's been fascinating to learn so much more about land I've known all of my life! Thank you for your contributions.
@@TheGeoModelshave you done any research on potential pressure points that might exist due to accumulation of these mudslides? Knowing this data could help us predict where land could lift up as the granite gets more weight on one end.
Thanks for doing this video! I live one county over from this location and find this very interesting. I tried to walk through a Helene mudslide to get to my parents house and it was like cold chocolate pudding, very strange. I won't try that again.
Yep, it takes the material quite a while to settle down after it comes to rest. Lots of folks have talked about it looking like boulders were "floating" in the mud. It's a strange phenomenon that really requires the most extreme rain to happen.
Very interesting video! I look forward to seeing more of these historical comparisons. Thank you for continuing with these post Helene videos, I find them fascinating.
Yeah I'll keep doing them. The TH-cam algorithm doesn't like it so much, but whatever. The history is quite interesting. This sort of thing happens pretty regularly in western NC; the trees just grow back fast enough that we don't have long lasting reminders!
Hello Phillip 👋🏻. I’m glad you’re talking about Helene. Prayers continue and help needed continues….
very true. will do what I can to keep it on people's minds
It's heresay and apocryphal - but my grandmother is of Cherokee descent, and she warned to stay far away from the lowlands when it was threatening weather. She spoke of her grandmothers warnings about groups of people being lost in flash floods and mudflows. I thought it to be a 'tall tale', but after last year's events, I believe it was ancient wisdom.
indeed. certainly not the first go round for this region.
Thanks Philip! Was on the BMCT a week ago. Started at Bowlens, got to HorseRock and my dog wasn't doing great so we bailed. She hurt her paw somehow and we carried her out.
Trying to get to Potato Hill next time to see if that area has changed much. There's a big rock face on the east slope, but I imagine that area is prone to slides and whatnot.
Thanks for the free information and entertainment.
Reminds me of adding just a little too much water to concrete mix. We have the same types of slides here in western Pennsylvania. There's a vain of red dog clay that slumps around here on occasion. Look up the Walmart landslide in Emsworth or Glendfield. It was propagated by construction excavation but we've had multiple along the same vain of red dog. Interesting part is the property was the old Dixmont sanatorium hospital that people ghost hunted after it was shut down.
I think it was from Hurricane Ivan. I really enjoy your series
This type of landslide is sometimes called a "blowout," and the namesake examples happened in 1942 or 1943 in Port Allegany, PA. Same type of catastrophic rain, just in a small area. A guy went out and documented them and said it looked the hillside "blew out." It turns out they are the real calling cards of extreme rainfall. You can get regular debris flows with less rain than it takes to make these.
Ivan did plenty down in old western NC!
There was a storm very similar to this in August of 1982 the tri-state area near Chattanooga, Tennessee. The sides of Etna, Signal, and Suck Creek mountains were washed away like that. I can’t remember exactly the amount of rain, but I think it was like
9 to 11 inches in about 2 to 4 hours.
That would do it. Thundersorms will do 20 or 25 inches in 6 hours or so in parts of Appalachia, but it's always localized. I'll check that area out.
I remember all that too! It was crazy to see but in my opinion it was nowhere near what Helene did in WNC / ETN. I lived on Signal back then, spent my summers at SC. The whole creek changed, bridges were washed out, repairs are still reliable today (the ‘sidewalk’ along the edge of the creek)… I commented on a video elsewhere right after Helene stating if that hurricane had stayed on it’s initially predicted course and dumped all that rain around here, I believe (not sure) it would have spared so many lives and homes. Looking back at the YT weather channels and their radars, the little wobble at the last minute saved our area. There would have been lots less devastation had we gotten it vs the ‘hollers’ in WNC. I’m so sorry for everyone affected. ❤️☮️
Just a brilliant fusion of the old and new, Philip! 👍
Such important geological perspective, Philip. Thank you!
I admit I have spent a lot of time looking at it for the past few years.
Logging contributed to the 1940’s flood. Much of the tree cover had been removed from the beginning of the century until the flood. Most of the lumber left the area on Tweetsie. But Tweetsie’s tracks were lost to the floods and the timber industry collapsed. The clearing wasn’t for agriculture although it became agriculture for awhile. It was the logging that denuded the mountains. Extractive exploitation.
That flood had 2 storms much like before Helene. One storm came from the gulf and the other from the Atlantic. The Stoney Fork Community was devastated with multiple deaths from flooding and landslides.
Fair point. Don't you have a law in the US that the de-logged forests have to be re-planted? Here in Czechia, the forest management must re-plant the logged forest within two years since the logging.
@ I believe that today most places require replanting. But in 1940 there were no such requirements.
However, - The forest was regrown by the 2024 Helene storms, but we still had devastating floods. .
@@Alarix246 Perhaps you missed the point of the video - the forests had REGROWN
@ yes true but the amount of water was historic and unprecedented. Again it was 2 storms. The hurricane dumped more rain on previously saturated soils. The fact that the forest had regrown saved us from an even worse situation.
I just love your videos - the best there is on this topic and I'm super impressed. (I'm also a Carolinian so yeah, really love these).
respect. they will keep coming, though the TH-cam algorithm don't like em anymore!
I am so pleased to watch your videos. I have always been interested in geology and topography of areas. Thanks for your teachings and the reminder of what mother nature can do and has done.
I have been watching a lot of videos lately about over forestation in the late 1800's and early 1900's. Southern Missouri's and much of the Appalachian Mountains was clear-cut devastating the landscape. Much of the lumber was used for railroad ties under the tracks, bridges, and building rapidly growing cities. It was incredible how much forest land was decimated rebuilding cities like Chicago after major fires. The area across the lake from Chicago was virtually stripped of all trees just to rebuild Chicago after the fire of 1871.
Yes, in the Missouri Ozarks we have the Ozark National Scenic Riverways that are all streams that have gravel bottoms from that era of clear cutting. So much soil washed down with rock and gravel that over time the soil moved on leaving the gravel in the stream beds. The logging camps/sawmills are famous in that region and the ties that came out of that area built the railways. Amazing history. They also nearly let us with no deer and elk use to be common but are now only reviving due to being reintroduced. The logging destroyed much of the eco systems of the area.
Thank you for a great explanation. I grew up right in Sugar Grove / Vanderpool area. It’s very interesting looking at what happened in 1940’s.
It was a huge event...about as much landslide activity as can happen in this part of the world. If it had gone like that today it would still be global news. Like Helene, 1940 had "hot spots." West of Sugar Grove (like west of Georges Gap Road), it was completely out of control, but just a few miles east it wasn't nearly as bad. The hardest rain bands can be pretty localized, and differences in the rock and soil are important too. There's an area down in yancey county that is likely geologically similar to Sugar Grove, and it is covered with old scars like Sugar Grove and just got dozens of new ones with this storm.
I've seen scars like this in the Appalachian mountains in VA before that looked like a creek bed, but there was never any spring it's just coming from the top of a hill.
A big one recently took out highway 250 in VA.
Great analysis Philip!! I was close to this particular area yesterday. Thank you
Thanks. I need to get up this way. This part of Watauga did similar things in 2004. It would be interesting to know what causes these small but rapid slides, in terms of soil and rock. Over on the Blue Ridge Escarpment east of Boone, the 1940 slides were much worse. I'll show those next time.
Love You're channel, watching from Selkirk, Selkirkshire.
very cool. glad you find it interesting.
Another great video. I am learning a great deal.
The bedrock is so close to the surface, there is not enough soil to absorb the water, so it just liquifies (quick sand) the thin layer of soil above the bedrock and it slides off.
Really enjoy these videos. Started watching after the storm since I live close by in northern Spartanburg county SC. Great video!
I'm just down the road from you at exit 54 on 85 in Greer. Glad you find the videos useful!
Always interesting material in your videos, no pun intended. USDA data and more recent aerial imagery have shown this reforestation over much of the eastern seaboard as old time ag lands are abandoned and return to forest. This has actually had a modest effect on air temperatures, slowing the trend of warming seen in other parts of the country. Thanks for all your videos!
I’ve never seen or heard of your channel until helene. You have really opened my eyes to earths geology and the devastation that Mother Nature can cause. Amazing work. Thank you.
This is why I find it so disturbing that these people are rebuilding in these areas, when you tell them that this is going to happen again they just refuse to believe it.
Especially interesting to me as a Watauga County native and resident. In the mid 70's as an ASU student I took 2 semisters of Geology. One thing that stood out in the class was the professor talking about how Rich Mountain "Tater Hill" was an ancient landslide on the Highway 421 side. I knew nothing of this. My grandmother was still living and I mentioned it to her and it was common knowledge to her generation. Since I watched this last night I've been searching for those 1940 aerial photos and can't find them online. If you could provide direction I would greatly appreciate it.
Ima in mountains of EastTennessee(11 generations)..let me tell ya..if ya cut away anything from honeysuckle lumps,tress,cudzue,ironwood,scrap trees..even mayapple root systems..it will cause the dirt to shift in time on our hill sides.Dry,wet,cold,the normal stuff will come back and get ya.Gotta be mindful.
I saw your scale model video clip showing what can happen if you remove a landslide toe. Makes a lot of sense to see visually why they've kept those toes of slides along Hwy 9, even though they're close to the lane. I wonder how DOT will try to clean those up without causing future failures. The one with the automated stop light in partiular.
frequently it involves sticking sort of hardware into the slope, or completely re-shaping it to be more stable. in our region, with our geology, it can be tough. they're working on dealing with I-40 at Swannanoa Gap as we speak. If you have to remove toe, you would need to remove some of the slide block to reduce the load. Even if you do this, once it's failed, the slip surface is already weaker and is a conduit for water, so they mess continues. Keep the excavators and dump trucks fueled up...
Wow, great video as always. Thank you brother.
Fascinating! Thanks for sharing your expertise! ❤
A question occurred to me watching this video. I had a small "landslide" in my back yard during Helene - about 4' deep of mud and rock that collapsed and slid across the narrow back yard and hit the house wall. But... it was a cut bank. Grading work was done there to expand the building site, definitely in 2000 and possible in 1973 as well. My question: is that a landslide, since human activity was involved in altering the slope, or just a human-driven collapse? I see comments about 2,000+ landslides in this storm. Are those all on undisturbed natural slopes? Is there a boundary as to what constitutes a landslide? I guess I'm just asking about the definition. Do we differentiate between "natural" and "anthropogenic" landslides? (P.S. By the way, great video, again!)
Yes, we'd call it a landslide and map it as one. It would be noted that the slope was modified. It's useful to know/record because some materials will hold a slope no matter what, while others will tend to be fail even at angles that "should" be stable. So yes, it's a landslide, but one on a modified slope. It's an important category given how many road embankments went bad during Helene.
@@TheGeoModels Thank you!
It almost looks like a paint bubble. When water drips down a wall, the paint is actually keeping it contained and stretching until it can no longer hold it. Then boom! It bursts. Leaving the rest of the paint intact.
interesting analogy
Thank you, appreciate all this information!
So in 1916 when the mountain landscape had been decimated by deforestation there should have been tons of landslides
there were indeed. it's hard to tell which scars are from 1916 because there weren't air photos, but it would have been a similar type of thing
From the Asheville Mountain Xpress, June 16, 2016: By July 16, 1916, the tail end of a hurricane, coming close on the heels of another one, had dumped 22 inches of rain on Western North Carolina in 24 hours, inundating the already sodden valleys. Mountainsides tumbled, and rivers overflowed their banks.
By the time the twin storms had passed, at least 300 landslides had been recorded and 80 lives lost. Dams and railroad trestles were destroyed, and residents in the communities along the French Broad, Swannanoa and other rivers were left with little except one another to rely on.
I think the biggest cause of the slide is existing springs when I was driving down to florida to rehab my summer house I saw at least 40ft long jets of water shooting out of the cliffs along i75 some where just a couple feet from pouring into the road the amount of water that sucked down into the rock is crazy
After ten days on a sinking ship, in an F5+ hurricane, this mudflow almost put me back to sleep this morning.... lol excellent work here. I wish you could see my 2010 Nasville and surrounding Middle Tennessee, flood pictures. 5 out of 7 vary large apartment buildings went under with that office bldg 86ed under the water. Only an F5 explains the Rainfall intensity, in Waves, there that May day. These Pictures are the kind of places I go in a storm LOL... Sailors are all wet..... My many days hiking and climbing those areas over my lifetime can't remember all this beauty and the Grand Old Mountains.
The liquid earth flow you describe reminds me of a term I’ve heard regarding effects of earthquake agitation in fill areas near coastal waters: ‘liquefaction’. I’ve heard this used in places like San Francisco Bay, and Seattle.
Ostensibly ‘solid’ foundations for buildings and highways can turn to liquid, rendering structures extremely precarious, with potentially catastrophic consequences.
Thank you so much for your super-informative videos!!
yes, this is essentially a form of liquefaction. with earthquakes, the shaking rearranges the soil particles and makes them "squeeze" the water between them. In the case of these slides, a similar thing happens, but no one knows exactly which part of the slide process makes the soil particles shift around to do the squeezing. I talk about the idea in the previous video on this channel. One way or another, though, they are essentially the same process happening on different topography.
This is like the slide that hit my house in Jackson County during Helene, crazy to hear and then see the wave. Very fortunate ours didn't have more mass and the foundation held.
Were you home when it happened? Was it Friday morning?
Thanks Philip!! You are a natural born teacher. Many may play the game well - but few can teach it. Question: I watched a typical YT video showing damage from Helene in the NC area, along one of rivers that showed massive erosion that had cut away at a bank with a home atop (home was largely unaffected). There was a 6- or 8-foot seam of what I would call virgin gravel about 15 or 20 higher than the river and about 5 feet below the home's elevation. It was obviously smooth, rounded river rock mixed with 'class 5' type material. Would this have been a deposit from a previous flood event? It was interesting to see the distinct seam of material.
Try Silvers Gap Rd Burnsville Nc 28714 we had Venturi effect happened here with 20 + multiple lands slides from several peaks we have 3 enclosed valleys with water from all three , feeds Cane River into a bridge went over 50 +feet here blasted the river out below here cut like a large pressure washer ,I own a peak I can show you up close if want to.
I'd actually like to see that. Those mountains have about as many scars as the ones from Watauga! I guess it's from 1916 but it might be 1940 too. Looks like it did about the same thing this time around. Yall got hit hard on the trees up there too for sure. I'm looking at satellite imagery as well as this lidar. just over the ridge to the east they got countless slides too
That would be an interesting video lesson! I'm in Michigan, got interested in geology because I'm on one of the Great Lakes. Moved away a couple times and each of those locations had fascinating geography as well. One was at the foot of an ancient prehistoric waterfall even before the last ice age. I would enjoy learning about your particular spot on this earth.
Did any houses survive in there? Looks like everyone built their house right next to the creek
Thank you for sharing! Let's hope we can learn something from this.
This is different from liquefaction? In my mind, the movement and churning of the material would quickly adopt the moisture it encounters on the surface, especially as it funnels into a waterway.
On the South Fork is the New River, I can show a spot where there was a huge Hugo landslide, you can still see the scar although nature is slowly healing it.
The trees hold back the soil. The 1940 photo looks like New Zealand farm land after a cyclone. Some cleared land has been allowed to return to its previous state because the slip chance was so high.
There's a TH-cam video of a landslide of this type happening in New Zealand a few years back. It's post cyclone. The slide had already released a lot of material, and dropped another chunk that turned to liquid while someone filmed.
Another excellent video. Is there really no true understanding of "how" soil/sub surface liquefaction occours?
Not in terms of consensus, no. You can't really creep up inside of a debris flow while it's happening, and the physical scale of real slides as well as the system complexity (soil particle size, trees roots, localized groundwater, etc.) makes it impossible to model exactly. I talk about the general idea in the video linked below. What I say is a summary of what folks do agree on; the challenge is understanding what causes pore pressure in the soil to rise suddenly. With loose soils, the answer is easy, but it doesn't happen only in loose soils.
th-cam.com/video/dikOL-qLua0/w-d-xo.html&ab_channel=TheGeoModels
@TheGeoModels You are too kind, I will watch that and have a ponder. Thank you!
Amazing, thanks for asking this question. I believed Mr prince but dang it is hard to accept at the same time. Sorta like how we are just barely beginning to u destined tornadoes. Seems humbling for our nature of advanced technology etc.
Is this process a cross between earthquake soil liquefaction and a volcanic lahar?
Yes, that's not a bad way to look at it. It all comes back to the water between the little particles in the soil and how it gets "squeezed" when something gives the soil particles a good joggling.
all the areas that got clearcut in the 1800s are growing back at a surprisingly well rate
What fascinating images! Mudslides in clusters. Thanks for digging into that for us. I've watched several of your videos since Helene and I've been quite interested in the mechanisms of flood and land movement. I have a question which you may have addressed previously and I missed it. But here goes...I have heard from several residents of NC and TN saying that the extent of the flooding could not have come from "just rain." They believe dams failed. They haven't been able to provide specifics on which dams failed. I realize there are probably a lot of small old dams built on private property that have been left to decay. These could contribute in some very local incidents. But I have not seen any media coverage of failed dams. Some might say there are coverups and such. It seems to me that the incredible amount of rain the area received in a short time was more than sufficient to create devastating floods in mountain valleys. The very shape of the land creates a potential for catastrophic floods. Are you aware of any dam failures that could have made the floods exponentially worse or are we just not capable of understanding the enormous volume of water dumped into mountainous terrain? I think nature plus terrain are perfectly capable of bringing calamity, no conspiracy theories needed. Any thoughts you would like to share?
There must be plenty of archive aerial footage to show if there were any dams...but consider that over millions of years, natural events such as this have literally carved out all these valleys from what was probably the bottom of an ancient ocean. Anthropomorphic global warming does not help, but nature has seen it all before!
Nope, no dams failed. They're all still there, and you can go see them if you want to. Many of the extremely severely flooded locations don't even have dams anywhere upstream beyond small farm ponds, etc. The idea of dams breaking went wild, but it just didn't happen, and looking at google maps can tell you that because you can see there aren't dams there to fail in the first place. What happened was heavy rain on saturated ground over a huge area. It was basically a regional flash flood. All the rainwater went directly to runoff...almost like the whole landscape was a parking lot. That really blew the top off river flows. If the hardest rain, fast rain (Helene itself) came first followed by days of pretty hard rain, the outcome would likely have been different. There wasn't any weather control machine either...
The idea of "dams being opened" was popular too. As above, there aren't even dams to be opened in most places. An emergency spillway (the fusegate) opened above swannanoa to stop the dam from breaking--this literally saved thousands of lives, without any question. Waterville dam on the Pigeon River released lots of water to accept the incoming flood; this damaged I-40, which is in a bad spot to begin with, but was necessary to keep the dam from failing...and killing thousands of people. Duke opened floodgates near Charlotte to accept the floodwaters--the water form Old Fort, Marion, etc. goes there. this flooded houses, which has happened before, but was also necessary. Erwin has no dam above it, Pensacola, has no dam above it, Barnardsville has no dam above it, Old Fort has no dam above, Chimney Rock has no dam above it, etc. etc. It's a reasonable question to ask, but it also has a reasonable answer. It just rained too hard and too fast after a really wet couple of days!
@ I have replied to comments about dams failing with hesitancy. People can be very militant about their opinions these days. So many are unwilling to look for facts or listen to possibilities. I try to get folks to think about the consequences of 30 inches of rain over such a short period of time in mountainous terrain. But conspiracies seem to appeal more than facts. As for the government controlling the weather...I don't waste my time commenting on those statements. Thanks so much for your reply.
@@laurachapin204 It's certainly a hot button, and if you lost everything, you'd definitely want to know why. At the end of the day, though, if it rains more than half the year's rain in a couple of days, you will have a problem. There have been many such events that were much worse and more intense in the Appalachians, but they just hit smaller or more remote areas. It's not a new thing, and even old Davey Crockett lost his childhood home to a huge flood on the Nolichucky in 1791...which closed the state park at the location of said cabin this time around. It all seems so unbelievable because we just haven't seen one of these in our generation, really. If you were alive for the 1916 flood, the 1940 would have been a "not again" moment but you would be more accustomed to it.
@ I suppose floundering for an explanation every couple of generations is better than, "not again" every ten years. Either way, it's certainly an apocalyptic event for those in the path of floods and landslides.
Enjoy watching these 😊
Thank you for your work! 🏞
The Caudill cabin tragedy, Wilkes Co. as well. 🙏
I'm looking into that. Very interesting story.
Hello, thank you for sharing this information! If you need some aerials in Watauga County I would be glad to help if I can. Thank you!
really enjoyed your aerials early on...some of the first looks at watauga, for sure. the vanderpool footage was especially valuable. Figure there's snow on the ground up that way now. I'd actually love to see an aerial of the slide I talked about in this vid...the one up in Sugar Grove. it's up on the west side of georges gap road, just past where dale adams road comes in. I figure you probly already know that! Anyhow, if you had a fly over of it, i'd be keen to see. We'll see it in new lidar this summer some time.
I find it so interesting. We were so worried about landslides behind us. Our neighbor, who passed years ago, said they had a landslide behind them, after they had clear cut for an apple orchard. I know the mountain behind us isn't super big but it's concave now up above their property and not above our side of the property. 3 homes back here and we all worry about this side of the mountain, since the other side has had a landslide many, many years ago. Is there a place you can search for landslides in the past? I haven't been able to find anything about the landslide our neighbor talked about. It's always made me nervous. Their land sits about 6-8 ft higher than ours does. Just amazes me! And scares me after Helene. We are in the outskirts of Banner Elk.
Isn't it basically like using water to wash dirt off of a rock After a certain point of saturation, the lighter particles start to float above the heavier Rock underneath, and the agitation from the wind and things, moving the trees and roots add a blender effect that agitates the soil allows for more water to penetrate, turns to liquid and then it runs downhill
no, it's more like when you step on the sand at the beach, take your foot off, and it turns to jelly. The process works just as well without trees and wind. basically the hillside doesn't slide when it's dry because all the little pieces of rock that make up the soil rest against each other nicely. With too much water, they lose their grip on each other, and the water prevents them from regaining their grip on each other.
There is a house in north Georgia I am now NOT going to buy after seeing your Helene videos. Thank you!
yeah north georgia gets these occasionally. They had a big one over around Hiwassee in the 1960s. Localized, but rowdy. just depends on where the weather goes.
It seems a shame that we don't learn from history. The folks in the 1940s landslides must have learned to let the trees take over all that farm land. I suspect the majority moved on to better land for their farming but as time fades the memories and new people buy up that land, they have no idea of the time bomb they are living on. Just one big storm away from a repeat.
I'm curious as to what steered them away from the open land. It was obviously being curate somehow; I presume it was grazed. Something was keeping it open and orderly. there are well established fence lines, so I guess it was a livestock sort of thing. Those air photos are really cool. There are literally thousands of 1940 slides to be seen county wide.
Slide deforms to slump then disaggregates into a debris flow. The key is that the grains keep moving because of grain interactions. On shallow slopes they don't incise.
From steep to shallow slopes, the mass transport process transitions from sediment erosion and incision, to non- erosive sediment bypass, to sediment deposition, as energy dissipates.
It is, by definition, a debris flow, it just doesn't erode in this case.
I was talking with green cove residents during the race/cleanup, they couldn't tell me when the trellis bridge ended up in the river, they assumed it was 1918, but it was much to young, the 1940s flood helps explain that, for context into that drainage.
Any geology students looking for thesis subjects? No shortage in WNC.
If you take saturated soil and put an earthquake under it, you get a similar substance. As the soil breaks up to tiny particles in the water it is less cohesive than soil with that amount of water in it. The added vibration allows the soils to break apart into a slurry of mud and water which lowers the friction and moves like water on a slope. But it still has the mass or weight if you will of all of it's components. Soil, rocks, water, etc. Everything it contains which is usually much heavier than just water of that volume. You can also find that phenomena on the shores of a body of water. If you walk out to where the water level is just an inch under the soil or sand, your body weight and motion can liquify it and suddenly it won't support you like it did before it liquefied.
So very interesting! Thank you!
glad it was interesting
So, sounds like a follow up talk on high precipitation landslids this year in Ashville is due🤔😅 (if the conference if stilloccurringthisyear amongthe clean up). Another great video and easy to follow explanations
yeah, that was just where they hosted that spring. It's an annual conference, and it's in Harrisonburg, VA this year. Someone from our organization will go...I myself need to be mapping geology elsewhere in Virginia.
I'll link the abstract to the Asheville presentation below. When I was writing it I was genuinely thinking about landslides cutting off I-40, I-26, and 321 or something like that. I admit I didn't expect river flooding to do it, but it's the thought that counts.
gsa.confex.com/gsa/2024SE/webprogram/Paper398358.html
Your videos are amazing! I wish you did them in something more like Blender, though!
I had no idea this happened so close to the source. What can be done to prevent this in the future? Deep post based fences toward the upper terrain? These killed many, and we can learn how to save lives in future!
Tell me more about Blender.
Planning is the only way around it; you just have to be sure people aren't in the way. You can tell where slides can potentially happen, and you can estimate where they'll go. People should avoid those areas. You can't tell exactly when or where they'll happen, and it's not possible to armor or reinforce every single slope above a house, so avoidance is the way around it. With lidar imagery and our knowledge today, it's possible to avoid hazard, but a lot of structures are already in the way. They don't need to be moved, but people need to know where and when to go when an event like this is incoming.
@@TheGeoModels Blender is a free, open source app that can be used to create anything in 3D. It can be used for 3D models, 3D rendered movies and terrain mapping in 3D. I suggest using google to search for BLENDER and GIS.
I thought that it might be possible to drill some posts 10 or so feet into the ground, just to create a wedge shape that would direct any uphill flows around a house. I would definitely try it if I was living in an area prone to such hazards. Thanks!
kind of like tall rooting plants help hold soil better than just grass. Seems like the Helene video showcased one that was on the edge of yard/forest.
Good vid exellent topic.. subbed!
thank you. interesting but challenging event, to say the least.
Is it possible that this event was actually a once in a century event instead of a once in a millineum event especially considering 1940 now. If so would that mean remapping what the riverbeds could reach? Because if that's the case then this wasn't the highest water level possible
yes, extreme precip events are actually pretty common in the appalachians. they tend to be more isolated than Helene, though, which was impressively regional. with warmer oceans and global temperatures, the jet stream may act differently, and we may see more of these big region-scale events. they have a fair bit in common with the Valencia, Spain, floods, the Ahr Valley in Germany, etc etc
Thank you👍
Thank you for these debris flow videos even though they scare the daylights out of me!
just have to not be in certain places when it rains too much!
@ It’s hard to know where to go when it’s your home. So unpredictable…
@@amandalynch9727 exactly where slides will happen is, but you can definitely tell where risk is present. sometimes moving just a few hundred feet is enough. we can tell when the weather is right to cause these, and perhaps communities will be able to settle on safe spots to gather in for the few hours when that weather is moving through?
@ Definitely need to be proactive, but I’d be the one to get taken out trying to find a safer spot.😅
I may have read a little about the event in Asheville after the video. Is there footage from field trip 2 by any chance? Am tempted to buy field guide 67 as well to see what was said. Hope you had a good new year!
yes, a good new year, thank you!
you mean the conference? I think it's just guidebooks; the mindset was different pre-storm! They are quite interesting, though, and generally well illustrated. There's a lot of good background about the area and why it looks like it does.
Wow! I thought landslides only happened in California. If the people only took your presentation more serious when you were in Asheville!
yeah that was a professional conference...sort of a limited audience! we have been working on producing materials that talk about the hazard for a while, but it's tough to strike a balance between awareness and over-cautiousness, which people get tired of. We'll keep after it though
How much of the historical loss of chestnut trees made these type of slides more prevalent?
Hard to know. One would need to make an intensive study of landsliding from the 1800s or before, and it's almost impossible! I'll show some slides from the 1840s in a coming video. I would think Chestnuts were still all around at that time, and honestly the woods and soil behaved about like forested areas did during Helene. It's a fascinating question, though, and I bet someone has thought about it.
Most damaging was the wholesale clear-cutting of every tree in sight and no replanting whatsoever .
The majority of the land that comprises the National Forests in the area , were once unimaginably vast barren hellscapes of gullies and stumps .
Think about that the next time you look at the seemingly endless stands of trees in the Pisgah and other National Forests in the region .
At one time , it all looked very similar to the Copper Basin prior to reclamation and reforestation .
@@kaboom4679 im nitpicking but id say it was free grazing animals for the most part, the mediterranean area and middle east are largely denuded from goats afaik. between collapses it got overgrazed. Most tree roots are shallow and small trees put out extensive systems, trees obviously put out a bajillion seeds, stumps sucker. Now theres so much less topsoil its easy to blame the trees.
Another wonderful video. I could and have listen to you for hours. I am a teacher and am wondering if you could possibly add some map overlays of pre colonial and colonial settlements. Having hiked extensively in the NC mountains doing historical research, it would be interesting to see if the ancient peoples settled in areas outside of 1000 year flood zones, especially if super imposed with a map of where the mound builders left their mark.
I am looking for the same material myself. I've never found any representations of "really old" settlements, either Euro or pre-Euro, that are good enough to put on a map. You can't really see good evidence in lidar either. The best I have done is to find a few landslide documented in the 1800s, but that's about it. It's a good question, though, and I wish we could answer it!
@@TheGeoModels John Lawson made-some rough maps and found his account, while not always accurate, it has interesting information. I have also been looking into the paths of the “Over Mountain Men” of the Revolution Days interesting as well. My ancestry is the Clevelands and Coffees and others and have spent two decades following their pathways. The info is somewhat there but scattered. Still looking for Creation and Stories from pre contct, which is somewhere but again, in scattered accounts.
@@starloegalletta Yes New Voyage is one of my favorites...read it many times. It sounds like Lawson got up into the Piedmont, but maybe not too much farther west than Charlotte area. He describes the granite "pavements" around Lancaster SC (like 40 acre rock) and similar areas in good detail, for sure. The Over Mountains route is an interesting one, and they had some oddball weather themselves that fall when they were headed east. I'll have to read more on it, but it sounded like it might have been a one off tropical system as well.
When you dig into the hillside you remove material from below a higher grade to flatten it as the ground settles it can create voids or pockets of silt or not ideal soil and as the water soaks in it compresses and gets heavier pulling away from untouched hillside and the untouched hillside falls into the saturated graded soil below and washes over or into it and can even go under it and continue the original natural stream location and open up the graded soil from above
We had that happen here in Santa Clara county California in the eastern foothills in 1983 after heavy rains.
There was one pretty recently north of Gaviota State Park and east of Lompoc...2020 or so, I think. The field look exactly the 1940 photos in this video
I have watched all of your videos and they always fascinating
Is there any such data collected or visibility that will pinpoint whether the southern side of the mountains or northern side of the mountain got more rain
Vice verse also analytics on eastern side or western side of mountains - mudslides homes that were much affected
I am originally from the state of Maharashtra in India and we have the Sahyadri range ( more famous as western ghats) of mountains tuning north to south
The western areas receive more rain n hence better harvest whereas Easter side do not get much rain so drier and
Just wondering if such a feature exists in the Appalachian that will help current/ future communities make an informed decision on housing
Thanks again for an excellent research work
It seems like the south slopes might have gotten more, but the topographic wavelength is quite short, so most of the ridges, etc. aren't quite big enough to have a true rain shadow. That said, south slopes did, in general, seem to have the more substantial debris flows. You can't take this too far, because bedrock structure tilts down to the southeast, so there may be a bias there. In the big picture, though, this (and 1940) were absolutely upslope rain/orographic events, with air masses rising from 300 m to 1km or so very quickly.
th-cam.com/video/XWllts4-bts/w-d-xo.htmlsi=iuE04HvpftkSp1Wv&t=240
It looks like at the 4:00 mark in the video, there's a large tree stump, which was apparently cut down earlier. The chopped pieces are visible in the image as firewood.
Could it be possible that this partially dried stump somehow caused this mudslide?
Do you know if this 1940 storm had any influence on efforts to protect the ridge lines and regrow the forests? It seems like a fascinating potential connection, and I’d love it if you could point me in the right direction.
What is the elevation of that little mudslide behind her house? My mind was wandering around the thought of Springs. Is their a possibility of correlation between elevation level and how that geologic structure could allow springs to pop open somewhe suddenly during a Helene event.
to some extent, though the complexity of the bedrock in this area prevents consistent spring elevations from forming like you might see in west virginia, kentucky, etc. it's likely that bedrock fractures could concentrate shallow groundwater in that area, and really maximally saturate the soil
@@TheGeoModelsohhhh this is a good point. So MANY springs and constant soggy ground in WV. Eeek. What do we know about mudflows here?
@@Burningheartcelosia they's plenty of them! the geology is different and they tend to move differently, but west virginia has about as many landslides as anywhere you'll find.
@@TheGeoModels it’s terrifying! I live here. It makes things worse to have a poorly ran DOH and they do their little scalping and shoulder clearing every 8 years and then it rains and every cow path turned road is then completely trashed as if there was a big storm. And utility companies reallllly screw with things when the occasionally clear their lines. We need criteria for them based on science and not “20 ft back “ cookie cutter stuff. I guess this really focuses on areas prone to debris flows mixed with chronic manmade interventions leading to repeated issues and road wash outs. Maybe not the topic at hand but sorta related to springs, tree cover, debris flows
Summer of 2018 I didn’t know what debris flows were. The type of wash out in the area I was in had never been seen In Generations and was so unique. The places that flooded and washed out or had mud and trees and rock slam against the side of their houses. It was puzzling. To say the least. Now I think I know what happened.
Hoping for your appearance on Weatherbrains, the longest running weather podcast. It will be interesting to hear your inputs into the meteorological community!
yep, coming quite soon (Monday)! eager for the discussion, for sure
Hey Thank God the rain let up when it did. Things almost reached widespread mudslide level. We for sure had some mud slides. Near me at the top of a mountain drive entire old growth tree's moved down and blocked the road etc. If that had kept going it would have been massive. Would have took out many homes etc.
yes, it could have gotten worse, for sure. Fortunately Helene itself moved through pretty quickly...if the last blast of hard rain had lasted longer, we would have seen a worse outcome.
@@TheGeoModels yes for sure the last two rain bands brought the trees down in my backyard. Thanks for reply have a good one. o7
Phillips, is there anyway that I can get a link to the Watauga images from 1940? My family gas lived in Watauga fir well over a hundred years. My grandmother told me stories if the 40 flood shooting tibes of water from the mountainside, and I know believe she may have witnessed these types of slides. I would like to cross reference any photos of the mountain near my family land.
they aren't publicly available to my knowledge...we have them on hand from past research. if your family saw one of these slides, it would literally look like a blast of muddy water coming out of the mountainside, so I wouldn't be at all surprised if this is what they saw. At the link below, you can find an email for me. If you're able, contact me, let me know where your land is, and i'll see if we have the air photo for it. email address is next o my picture at the link.
princegeology.com/about-philip-prince/
From what I understand, from Raleigh to the outer banks is the top of the Appalachian mountains. That they used to be as tall as the Rockies or higher. And have eroded down to what they are. And in Bravard, there’s a chunk of the African continent where it broke off when the mountains was formed. Volcanoes was all around nc. A lot of history right here in the mountains of North Carolina.
Being near the New Madrid earthquake fault, could either of these slides have been initiated by a combination of hurricane and earthquake?
hey Phillip, are you familiar with Richard Montgomery's Dirt: The Erosion Of Civilizations?
I'm not...sounds interesting.
@TheGeoModels every time you talked about these slides and flows, i've been thinking about this and the mentioning of the detrimental effects of our "conventional" farming styles, from the fact that globally we're losing upwards of 24 billion tons of topsoil to erosion and these very conventions playing massively into that, to some of the most extreme outcomes like the dust bowl.
it would be super interesting if there was a way to find out whether there's a change in the amount and severity of these locally catastrophic incidents prior to and post european settlers large scale influence on the appalachian landscape...
@@HaileISela lots of folks are trying to figure that out. sediment records (like in Erwin, TN) might show that these things have been a part of the appalachians for quite a while. that said, slope modification and riverbank modification absolutely change the smaller-scale outcomes.
@@TheGeoModels well, if you find the time, take a look at Dirt... it's a geologist's perspective on the patterns of civilization and tremendously fascinating
What site do you use to see these images?
It's through my work with Appalachian Landslide Consultants. We map landslides for the state geological survey, so we have a bunch of cataloged material to support that. I'm not sure if any of these old air photos are floating around on any sites. I guess libraries might have them, but that sounds like a rabbit hole. Any particular area you're looking for?
@ I’m just really interested in all of your content and I’ve tried to look on google earth for my area and it’s all from years back and nothing up to date. You have some awesome content. Thanks for the reply
I’ve been trying to look at the landslides from the satellite, but I’m not sure what app to use. I’ve use Google Earth regular. Don’t say anything to Trees. I’ve used Noah NOAA and I can’t say anything so I’m not sure if I’m looking at the right apps to see the landslides off of 2268 Alpine Lodge area.
ODD, I WAKE UP THIS MORNING AND SEE MY COUNTY ON TH-cam !!😂 THANKS FOR THE VID !
it's quite a spot even without a monster flood!
Wouldn't it be kind of like a slip layer. We find those doing earthwork a lot. It's essentially just a porous layer of Earth that allows water to get in between a thin of earth an rock. The water adds almost double the weight an the minor amount of roots to stabilize the soil give way an release.
Video request: compare/contrast Helene versus Camille in central VA (Nelson/Amherst counties)
yeah that's coming up. got most of the the overlays done. it's pretty interesting. for a while, meteorologists said Camille was as hard as it can rain on planet Earth. I'm not sure if that is still considered true or not. central VA has had several of these, the most recent ones being in 1995. What happened with that one up on the Moormans and at Graves Mill was Camille level but just didn't get to any houses through sheer luck.
@ Amazing! Thank you! I’ll look into the Moormans and Graves Mill events, as I was unaware of either, only Camille.
Love your videos and thank you for all the time and effort it takes to put them together, as the results are both entertaining and educational, a rare combo these days. Thanks again and looking forward to it!
@@philipkomoroski210 glad they're worthy. Try to get it rolling this week. It's quite something. Central Virginia is actually sort of a hot spot for these really off the chart extreme things.
Interesting to see the historical context yeah nature moves on its own timescales and we must either heed her warning or pay the price of our hubris. I wonder if some of those older slides prime further slides where they deposit their material?
they definitely can if they stop in the right place or leave a steep lip in the right place. in this region, big, slow moving landslides can make dangerous setups for debris flows. the big slide creeps along and pushes up a big, steep "toe," which is then more likely to fail. there have been some huge examples of that process in the southern apps.
Re: tree cover. I just read today that this area was absolutely stripped of trees to feed smelters back in the 1800s.
Hi, how about some food for thought; encourage the clean-up of slopes near residential areas of young trees and rotting wood for fuel, allowing the sun to reach the ground beneath the old shady areas to encourage new green growth.
We need to do this on a grand scale and with urgency.
I keep looking at the ridge across from me looks like sunken trees still standing straight. Just lower.
Could be. Where you looking at?
Actually, your video is pointing out a very critical issue that was ignored up to this point. As far as I understand Even after the major floodings you had in the area in the 1920s. No one thought about this is a critical issue going forward. Of course now is going to be top of the list hopefully and it's going to be very expensive to repair
Hopefully it stays on the mind for a while this time. This event has been recorded so much more effectively (no phones to film stuff back in the day!) that people will keep thinking about it. Something like it will happen again in Appalachia sooner than later, though hopefully not at such a regional scale.
You would wonder if the trees were added after the 1940 storm, to prevent more slides.
Massive change in industry around that time
Is there a certain degree like maybe 45 degree slope where this would not happen?
it's less than that! slides like this start to really pick up at around 25 degrees slope. The highest natural slopes that aren't cliffs in this area are usually high 30's degrees. You can get something like this on gentler slopes, down to 20 or a bit less, but it's less common. 25 degrees is a decent cutoff in this part of the world. If it's steeper than that and concave shaped, heads up.