Fire Science Show
Fire Science Show
185 - Recap on wildfire science
In the aftermath of the LA Pacific Palisades Fire, I've decided that instead of inviting one expert to discuss the event, I will give a voice back to those who already participated in the Fire Science Show and explained this fire (months and years before it happened).
In this episode, we recap Wildland-Urban Interface fires, with a focus on the "urban" part. We cover conditions in which such fires may happen and factors that contribute. We discuss the role of community preparedness and pathways in how those fires "attack" individual households. We talk a lot about embers and some ideas on how to mitigate them. Finally, we discuss the evacuation from WUI fires.
Some politics, a lot of science, decent amount of answers to most urgent questions. I hope you will enjoy!
Episodes and speakers featured in this podcast:
- 069 - Challenging fires at the wildland-urban interface (WUI) with Michael Gollner
- 117 - Global wildfire emergency and the key role of FSEs with Albert Simeoni
- 156 - Trigger Boundaries with Harry Mitchell and Nick Kalogeropoulos
- 159 - The WUI Problem with Michele Steinberg and Birgitte Messerschmidt
- 161 - Community evacuation with Enrico Ronchi and Max Kinateder
You can always find current episodes on wildfires at https://www.firescienceshow.com/category/wildfires-wui-and-wind/
The history of Japanese urban fires is covered in the paper Large Urban Fires in Japan: History and Management by Yoshioka H. et al.
Cover image credit: By Toastt21 - Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=157682430
From the Wikipedia summary of the LA Palisades Fire at https://en.wikipedia.org/wiki/Palisades_Fire
Thank you to the SFPE for recognizing me with the 2025 SFPE Fire Safety Engineering Award! Huge thanks to YOU for being a part of this, and big thanks to the OFR for supporting me over the years.
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The Fire Science Show is produced by the Fire Science Media in collaboration with OFR Consultants. Thank you to the podcast sponsor for their continuous support towards our mission.
Hello everybody, welcome to the Fire Science Show. My name is Wojciech Węgrzyński, I'm a professor at the Building Research Institute and in this podcast I talk with fire professionals on all things related to fire science and all things that interest us as fire protection engineers, fire scientists and the general public as well. And you know what, every time there happens a big fire, I feel this need to to provide some commentary, because a lot of you listeners are engaged in discussions, thoughtful discussions, with your family's colleagues around. I really like to to provide this type of overview of what happened from from the perspective of science. And recently. Recently, we had a massive fire. We had a fire in Los Angeles, the Palisades Fire, and some call it a wildland urban interface fire, some call it an urban conflagration. It's definitely a massive tragedy. Hundreds, if not thousands, of people have lost their homes, a lot of people lost their lives and it's surprising it could happen in one of the world's biggest economies, you know, in California, in LA. It's kind of shocking, but you know it's less shocking when you think that those fires similar to that perhaps not in the exact economical or personal tragedy scale, but similar happen all over the world. And in fact, as the podcast goes. I had those fires and I had those discussions with fire professionals in this podcast and every time a big fire happened like it kind of feels like seasonal. I have those episodes somewhere early in the year because there had been some winter fire, and I have those episodes over the summer because there had been some winter fire and I have those episodes over the summer because there had been large summer fires and it's just a repeating pattern and it's kind of sad. You know you cannot act surprised that this fire has happened, that this damage was done, and I was reflecting should I invite someone to talk about Palisades Fire here in the podcast? And then I thought you know what A lot has been already said. I've had really good interviews with really top specialists in the field who know their stuff and when I was revisiting those interviews, many things said in those interviews described exactly what happened in Ley and described exactly what will happen in the next location of a great fire if we don't act. So in this podcast episode I would like to take advantage of the vast library that Fire Science Show has created. There are already good interviews on the physics of wildfires, on the politics of wildfires, on the management of wildfires, on evacuation in wildfires, and in this episode I'm bringing bits of those episodes think about the best of where I try to really combine them into one narrative of the fire science on the wildfire problem and if you would like a deeper dive, you're very welcome to revisit those individual interviews. I think this episode brings a lot of answers from the scientific point of view what actually happened, why in those circumstances, this could and had to go like this, and what can we do to prevent future tragedies like that. So please join me on an episode with the fire science on the science behind wildfires. Welcome to the fire science show. My name is Wojciech Wigrzyński and I will be your host.
Speaker 1:This podcast is brought to you in collaboration with Ofar Consultants, a multi-award winning independent consultancy dedicated to addressing fire safety challenges. Established in the UK in 2016 as a startup business of two highly experienced fire engineering consultants, the business has grown phenomenally to eight offices across the country, from Edinburgh to Bath. Colleagues are on a mission to continually explore the challenges that fire creates for clients and society, applying the best research experience and diligence for effective, tailored solution. In 2025, there will be new opportunities to work with OFR. Ofr will grow its team once more and is keen to hear from industry professionals who would like to collaborate on fire safety features this year. Get in touch at ofrconsultantscom.
Speaker 1:So Joe Rogan predicted Palisades fire. That was the thing that was trending on my ex, or Twitter, or whatever we call it today. Joe Rogan has predicted the LA fire and when I listened to him, what he gave was a very good description, coming allegedly from his firefighter friend, who told him that in a good wind, in dry day, in a specific condition, it can burn down to the sea and nothing will stop it. And now, if you think about it, one thing that we can probably predict and I think that Joe Rogan predicted is that indeed, a fire may happen and the cause of a fire may be like that. It's just it's very hard to say exactly when it will happen and where exactly in the world will it happen. There's hundreds, if not thousands, of communities that are at the very same risk as Los Angeles policies and fire has not happened there yet. Maybe it will never happen, maybe it will happen in next week.
Speaker 1:That's the tough part that we don't know, and that's the tough part that we need to work around, because it's easy in hindsight to say that fire was inevitable. In fact, indeed, those fires could be inevitable. And if, in specific conditions, there's only one way a fire can go, it's not just like a fire had 100 ways it could develop and it developed in this one worst way possible. No, in those conditions, in this fuel, in these circumstances when the fire started, it just had one way to go and it exactly went that way. So once we understand that, we perhaps can put some measures to protect us, we know that we can put those measures. There's a lot of people working and I'm bringing them together today in this podcast episode to tell you about how we're working on solving the problem and creating a new reality where those fires are not tragedies that you need to make podcast episodes about. Anyway, before I start, I just really wanted to reiterate like it's a set of things, it's not one reason, it's multiple things put together that create the environment in which, and eventually, a fire happens.
Speaker 1:And also media attention often is on the ignition source. You know why it ignited. Was it an electricity line? Was it an arson? Was it someone having a campfire at the edge of the forest? I don't like to put focus on the ignition, because if the circumstances are correct, the ignition is irrelevant. It will eventually happen. And that's how I like to think about the problem to split it away from the probability of it happening, just assume it's going to happen and then figure out how it will go in different circumstances. This, I believe, is the fire engineering way.
Speaker 1:Anyway, let's try to define the wildlife-urban interface fire problem. Let's try to define when and how wildfires are a real threat to urban communities and in this podcast episode we'll definitely focus mostly on those fires that enter urban communities, not massive wildfires in the wild, which are also a problem. But here we focus mostly on really the urban interface. We're going to talk about the physics of wildfires, we're going to talk a lot about embers and how the farms transport themselves and spread. We will talk about the contributing factors and the community resilience and we're going to talk a little bit on evacuation as well. So a lot to unravel, but I think it's a good high level overview of the problem.
Speaker 1:So first I I would like to define the wildland urban interface problem and in wildfires entering urban spaces, and I had some episodes on wildland-urban interface In specific. I also had an episode on wildland industry interface. But here I would like to revisit episode 69 that I had with Professor Michael Gollner from Berkeley, california, whose authority in wildfires. He gave really good talks on television after the Palisades fire from Berkeley, california, whose authority in wildfires. He gave really good talks on television after the Palisades fire. So you probably could also revisit them to get a very short, sharp commentary on what happened. But anyway, in episode 69, I've asked Michael what is the we problem? And perhaps before we talk about it in depth, let's try to define it.
Speaker 2:Some of the definitions are a bit loose and it depends on where in the world you are. We don't even call it wildland-urban interface. We don't even call it wildfires. Down under in Australia you call it bushfires. But it's generally the burning vegetation and natural materials, undeveloped land. That's a wildland fire. It could be a forest, grassland, shrub, chaparral, but when it meets developed areas there's this interface. So it's an area where any of the undeveloped land beats our built environment and that's what we generally in the US now are calling WUI or W-U-I Wildland Urban Interface. I like to define it that it's not just the area where it meets but the area that can be affected. So if the fire can get in and spread a certain distance, as far as it can affect, that's all probably wildland urban interface, because, we'll learn, embers fly in. This wildland urban interface often starts from the vegetation or the forest or whatever it is, and spreads.
Speaker 1:How it differs from the normal problems you would have in your, let's say, house or whatever building you're designing. I guess the first thing is the threat comes from outside, but probably there's more to that right.
Speaker 2:Yeah, I mean it's a completely different way of thinking about the risk from the built environment when we're indoors versus outdoors, because we're now worried whether it's already spread to your neighbor's house and your neighbor's house is trying to ignite yours, or the vegetation is igniting the house, or embers which are small burning particles. Burning particles ignite from that fire, fly land, smolder and eventually ignite something in your yard that ignites your home or the home directly on, like a wood roof or in a crevice. But any of these mechanisms spread that fire from the outside into your home and the investigations into wuyi fires have been really interesting. See just just how that spread and how the dynamics are different.
Speaker 2:Inside a house we're so compartmentalized we either have we might have sprinklers to contain the fire. It doesn't put it out, it contains it within a room. But our rooms have, you know, drywall covering. We have doors and there's fire doors. Right, we try to contain the fire to its origin. Here. The fire is all around us and we don't often look at the exterior of a building trying to prevent a fire coming in. So there's a lot of vulnerabilities in traditional construction but a lot of the destruction it doesn't just ignite on the outside we actually see there's a lot of homes that burn from the inside out. You get one ember inside and then, with no one there, the home burns down and so there's wooey. Just takes a different type of thinking, and once you understand these processes, which which we can go through, then I think the mitigation measures make a lot more sense I like how mich Michael positions it as a fire coming from outside that eventually comes inside the house and then burns it from the inside.
Speaker 1:That's exactly how we see the damage. The houses burned down not because of insane heat from the exterior. They burned down because they've ignited and eventually each of those houses, at their individual level, underwent a fully developed residential building fire. Now in episode 159, I've invited two directors from National Fire Protection Association, michelle Steinberg and Brigitte Messerschmidt, who also gave me a good overview of the WE problem. Actually, in that episode, the main subject of this episode was to actually grasp what is the WE problem. That was the main subject of this episode was to actually grasp what is the we problem. That was the whole idea of the episode, but I think Michelle gave me a very good description. That's a great addition to the definition that Michael just brought in.
Speaker 3:The point is, what we're trying to describe is a problem of homes igniting during wildfires, and in fact not just a building but multiple buildings, whole communities, and we're trying to describe it in a way that defies kind of the scientific logic of it, if that makes any sense. So we're trying to draw a line. When you say interface that you assume there's sort of a line or a barrier or boundary. That is a nice neat definition for a very messy problem. The messiness comes when we're talking about what is causing the fire. So that wild land word gets in there.
Speaker 3:You can argue and I live in the Northeast of the US where many friends have told me we do not have wild land in this region, which I'd argue, yes, you do, but they see this. What is even wildland? We don't understand what that means, first of all. And then urban also has its own connotations of a city and people think, well, cities don't burn down from wildfires. So what are you talking about? What I guess we're trying to get at is the exterior exposure from vegetative fuels to buildings, and typically what we find in the US is the residential buildings are the ones that primarily are the ones that are at risk, primarily the ones that burn. So it doesn't mean that our commercial buildings are so well built. It just means there's a lot more houses than there are anything else and they've built in ways that make them very, very vulnerable to the exterior exposure from a wildfire. Even the word wildfire has its own set of definitions. But the presentation and why people get so confused is when we go beyond the sort of the why are things burning? How are things burning? Which is our sort of scientific question.
Speaker 3:We get into politics which is oh, if I'm defined, if my home or my community is defined as being in the wildland urban interface or in the WUI, then I either have to meet some kind of standard, or I'm going to get higher insurance rates because I'm seen as higher risk, or something bad is going to happen to me as opposed to somebody who's not there. Thinking, well, I have no risk from this problem because I'm not in the WUI, risk from this problem because I'm not in the WUI. And we find over and over again that those definitions don't make sense in real life. And now, ironically, because our government is putting a lot more money into trying to protect homes and communities at risk, now people want to be in the WUI so they can get grants and they can get help, et cetera, et cetera. So it's really ironic that we have people running away from and towards this definition. That in and of itself is not very helpful to describe what the problem is.
Speaker 1:I've brought that part because Michelle shows how fluid the problem is like. What is the wildlife urban interface and how to define it? And on one hand you could just go with a broad definition anything that can be at risk from a wildfire. On the other hand, you probably would like to have a map and on those maps you know plot which houses are in the way, which are not, because in order to execute some policies you probably need that map in the end. So we're trying to put a very rigid definition on a very fluid problem, and that's perhaps a part of the issue.
Speaker 1:It's very hard to create good preparedness when the problem is to some extent either defined in a too wide way, like anything 10 miles from a forest is a we. Is that a good definition? That means like half of the planet is in a wii. On the other hand, if you start narrow it down, you probably omit some that could be in the risk and they did not know they are in the wii. So that definitely is a challenge, a political challenge and also a challenge for fire science. How do we define those who are at risk? You know if joe rogan could define palisades and being at risk or la being at risk. You know, if Joe Rogan could define palisades and being at risk or LA being at risk, perhaps fire science should also focus on how to indicate which parts are actually in the risk. But the risk is also multifaceted.
Speaker 1:There are many, many ways, many things that go into the fact that the wildfire has happened, into the fact that the wildfire did damage that it did, and of course, there are physical things. So let's talk perhaps a little bit on the physics of those fires. What are the contributing factors? In episode 117, I've invited Professor Albert Simeoni from Worcester Polytechnic Institute and Albert is also a globally recognized wildfire scientist who's been dealing with this problem across the globe, from US to Siberia and all different types of wildfires and I've asked him first about the vegetation and the dryness of the fuel. Is this dryness the reason we have fire seasons? Are they always connected with the summer? I mean, right now it's not a summer on the Northern Hemisphere and we just had a massive fire. Yes, it's driven by the vegetation. I mean, right now it's not a summer on the Northern Hemisphere and we just had a massive fire.
Speaker 4:Yes, it's driven by the vegetation, of course, the immediate conditions at the time of the fire.
Speaker 4:If it's raining that day, there will not be any fire but it's triggered by the trend in the vegetation.
Speaker 4:So when I moved to the US from France, where I'm used to exactly what you described, you know, fires happen in the summer when it's past 30 degrees and very dry and the vegetation has dried.
Speaker 4:Actually, in the northeast of the American continent the fire season is in spring. So what's happening there is as soon as the snow is off the ground, the vegetation hasn't grown back and is very dry from the winter and you have usually dry conditions at this time and that's when you have fires. And it can be I don't know, 10 degrees outside and still you have very intense fires because the vegetation is dry and the air is dry and of course, if you have wind, you have the drought is dry and the air is dry and of course, if you have wind, you have the drought, little precipitations in the winter it's happening. Then when the summer comes, it's humid and it's not very flammable anymore. So now the eastern shore of the American continent is pretty humid, you know. So the fires move to west, where it's more like following the Mediterranean pattern than you need the summertime to have things dry.
Speaker 1:When I've talked with Albert, it was shortly after the fires in Hawaii, in Maui, and it was just when the fires at Tenerife started. I believe that was last year. So this discussion on the conditions in which the fires happen have twisted into what happened at Hawaii at that point of time and I think it's an interesting explanation because you can see a lot of parallels between those fires and the fires at LA Palisades. But if you look at Hawaii.
Speaker 4:It's on the side of the island which is actually not getting much precipitations because of the mountains, is actually not getting much precipitations because of the mountains. So on one side, on the eastern side of the island of Maui, you have the rainforest. On the other side, you have grassland, and this grassland is also due to the fact again, it's not only the climate, it's also the people, it's all the sugarcane fields and they're not now abandoned and they're completely choked by invasive grasses which are becoming very dry. But again, grass burns and it's not something that people will make the news. You know grass is burning all the time.
Speaker 4:What you need to have that in the news is you need that to impact people. And so the grass is igniting the first houses and then the first houses burn. And there is a big wind because it's coming down from the mountains and you have this effect. They talked about a hurricane south of Hawaii which was kind of with a big depression north of Hawaii, creating this kind of a venturi effect. And so you have big winds and it's hitting the first houses, the first houses burn, and then it's creating a lot of firebrands and it's landing on first houses, the first houses burn and then it's creating a lot of firebrands and it's landing on other houses and then you have a catastrophe. So in this case, grass becomes very, very dry in the dry season and if you have drought it's even worse, you know, but you need to ignite houses.
Speaker 1:And that was an important point. It's not just the dry vegetation, it's the conditions at which the fire starts at dry vegetation or involves the dry vegetation and then moves into an area where it can accelerate, grow and move into urban space where it's green and then just people. That In episode 159, when I talked with Michelle Steinberg and Brigitte Messerschmidt, more things besides vegetation were brought in, and those are actually things that are in our power to manage. So let's bring Michelle Steinberg once again on secondary ignition items.
Speaker 3:It's so much harder to deal with fire on this level of understanding how it's going to impact structures and where the actual risk of ignition is because you have wind, because you have fuels that you move from. Let's say you've got a wildfire coming through vegetation, you get embers into the mulch next to your house or the shrub or the flatbed of a pickup truck that's parked next to a house and these all become fuel for the fire that is ultimately going to take the community down and you think, well, that's not a wildfire anymore, because if it's in the mulch and it's on the deck or it's in the pickup truck, those aren't wild lands, those are objects, common objects around our homes and our yards. So it's super confusing to try to draw this line and the way we've tried to explain this to property owners and that's the thing I think I'm looking forward to talking more about sort of the fire protection engineering role here, because we're trying to tell people who are already built in a highly hazardous situation with materials that aren't going to withstand this fire. We're trying to tell them to do what they can do and what we know they can do and what they can control is the fuel which starts with their house and out to the extent of their property. That's what they have control over usually, and they can't control the wind, they can't control the national forest. You know, a mile down the road they can control.
Speaker 3:What does my roof look like? What does the vegetation look like right around my house? What are the other things that could catch embers that I can modify so that when we have this inevitable fire coming, there's things I can do to prevent my home igniting. So that's getting down to that micro level. And then, oh, by the way, if my neighbor's closer than about a hundred feet, I have to worry about them. And so we start to get people to work with their neighbors to reduce those potential fuel sources for ignition to homes.
Speaker 1:You also mentioned those secondary items, trucks and everything that you can have outside of your homes, right?
Speaker 3:Fences, flat wooden decks. We joke that you can design the perfect house and then the unlicensed contractors meaning everybody who wants to do it themselves don't get a permit and they go out to Home Depot or Lowe's or whatever and buy the stuff and tack a nice big flammable wooden deck to the house. So it is. That pathway of the fire spread are again things that now scientists are looking at much more carefully. Because we've already solved for the radiant heat. We already get it. Okay, we don't want big flames near our house Cool, we can usually accommodate that. But we also can't have any flame touching the house and that's where you get fire creeping through the grass, fire igniting a wooden fence and carrying it like a wick or a fuse right up to the house. So it's these appur have been now work on flammability of fence materials and arrangements and so forth, and you know the people who are experiencing it.
Speaker 3:We work with the communities, we work with the fire service. It was sort of our duh moment of yeah, we watch it all the time, we see it, but nobody's tested it in the lab. So we need to verify, which is really key, because otherwise the scientific community is not going to get the message because the firefighters the first thing they did in one of the first things they did in the Waldo Canyon fire in 2012 in Colorado Springs community just into this fire siege was run in and start to knock down wooden fences. That's one of the first things they did to triage to try to save homes was they knew if the fire reaches this fence, these homes are gone because it was connecting them all like a fuse, and we see that anecdotally over and over again in fires where firefighters have enough time to get in. That's one of the first things they're going to do is get rid of that link from the fire to the house.
Speaker 1:And if I can take you back again to episode 69 with Mike Goldner, we also talked about the role of fire brigade and our ability to manage those fires. Like Michel said, when they have resources they would take down the vulnerabilities around the houses which technically could be taken down way way ahead of time by the property owners. But when you are actually battling fire there's a limited amount of things you can do and I know there was a lot of critique on the management of things you can do and I know there was a lot of critique on the management of the LA Fire Brigade. I don't want to go into that, but definitely you have to filter it through the real ability of what those people can do when the fire happens concurrently at hundreds of houses. So anyway, giving the air back to Mike Goldner from episode 69.
Speaker 2:If you just have a small fire, a fire department can respond, put it out or they can protect the homes. But that's what's different in the wild and urban interface. You're not talking about two structures, three alarm fire. You're talking about maybe, let's say, 10 kilometer wide fire front spewing embers two kilometers ahead of the fire. So you got a huge area all being impacted. How many thousands and thousands of homes.
Speaker 2:There's no way you can have enough resources to protect them, and so you need a fire that's at that size and that speed and that scale, and that usually means dry conditions for a period of time, higher winds, low humidity, which happen all the time around the world, but are much more common in certain regions.
Speaker 2:You need enough vegetation and wildland fuel to ignite. And then you know, in some ways, our community is now a target, so you need a target that's receptive to a hit. And then that fire comes up, and if you start burning a lot of houses at once, very often by embers, just the fact that the embers can travel so far and land into such a spread, they tend to be responsible. Some investigations have said 50 to 80% of the destruction, and because of that fires you don't know where that next fire is going to pop up, and it becomes impossible for the fire crew to protect, and in a lot of these very fast fires middle of the night. So the Tubbs Fire in California, over 9,000 homes, the Camp Fire, 18,000 structures it becomes a full evacuation and fire crews are pulled out. Their only responsibility is saving lives. They're no longer doing structure protection, there are no resources, and so that's the epitome of the ultimate disaster scenario.
Speaker 1:So one more thing that goes into this ultimate fire disaster scenario and one thing that was definitely visible at the LA Palisades fire was the huge impact of wind visible at the LA Palisades fire was the huge impact of wind. For this, actually, I can talk from my own expertise, because I've researched the subject of strong wind and fire interaction in my wind and fire review work. And Santana winds, the ones that happen in the Palisades fire it's the type of wind that happens all over the world, the type of dry and warm wind we even have it in Poland, these types of winds that come from the mountains, exactly where I was born. So I'm very, very familiar with how these winds look like. But it's not just the wind that creates these extremely hazardous, disastrous conditions. It's also the way how the community was set up. And I'm not very familiar with L, with LA, and I've never been there. But I've seen pictures from the palisades. I've seen the pictures taken from airplanes overhead the palisades, I've saw some Google Street Views and a thing that you can immediately see is how tightly those buildings are. They're literally next to each other and because they're so close to each other, people want some sort of privacy, so they build some structures, fences, shrubs, to you know, separate themselves from their neighbors. So you have an extremely tight built environment with tons of presumably timber buildings that are surrounded by vegetation that altogether is very dry. You have a dry season, it's being dried even more by an extremely dry wind and then a fire happens, and now the fire doesn't have to spread like a wildfire.
Speaker 1:My guests have talked about the methods of spread, more like we've seen at, let's say, fort McMurray fires, where you had a wall of embers flying into the city igniting items and eventually they would be contributing In. Here I think, and that's my hypothesis, the fire was more like an urban configuration type of fire, more like home-to-home fire spread, more direct spread, and if you want to learn about those types of fires, it's a really valuable lessons come from Japan. So the reason is that Japan also has high density of residential developments and traditionally they would use a lot of timber in their houses and Japan was troubled by those massive urban fires at strong wind conditions for centuries. There have been hundreds of fires in Japan like that. Most recently, the largest fires was in 1976, the Sakata fire. Anyway, japanese have a term that they use to define those fires. They are called taika and they connect this term of this urban fire, taika, with the size of the damage, how much of the city was involved in the fire. And when you look at the history of taikas in Japan, you can clearly see most of them happened at strong wind conditions. Some happened after earthquakes. There's also a thing that those fires can develop after massive earthquakes, but most of them happen at strong winds.
Speaker 1:And what's even more disturbing when you look into the history of those fires is that the fire spread velocity or the fire spread rate can reach insane numbers in a dense, timber-based community at strong winds. So there were 1934 Hakodate fires where the wind speeds were around 20 meters per second and perhaps a little bit more, and the fire spread level on the leeward side was almost one kilometer per hour. Can you imagineward side was almost one kilometer per hour. Can you imagine that that's one kilometer per hour? That's how quickly the fire spread into the community. One hour later, the fire is one kilometer away. This is like on the scale of fire science. These are insane numbers.
Speaker 1:At the mentioned Sakata fires, the wind speed was 12 meters per second and the fire spread rate was between 50 to 100 meters per hour. That's also a lot. 100 meters per hour is a lot. In the Great Kanto earthquake fire 1923, perhaps the biggest, best described Japanese Taika-type fire wind was approximately 8 meters per second. So 8 meters per second for most of the world would be somewhere around 95th percentile of wind. That's your normal strong wind, and the velocities were 200, 400 meters per hour still a lot.
Speaker 1:So looking at the history of those fires in Japan, you can see that definitely there is a significant link between the wind velocity and the fire damage when the fire is within the community. And a good thing that you can learn from that history is that I said the last 1976 Sakata fire. That's almost 50 years without those huge fires. There was one that didn't meet the area requirement to classify it as a taika and there were some taika fires after earthquakes, like there was an earthquake in Tohoku some years ago. There was an earthquake in Kobe where those types of fires happened, but not due to wind. Why? Because Japanese have implemented really good mitigation plans. They have created zones in which you have to farm protector houses They've enforced using non-combustible materials and they pretty much broke the chain. It's not just old style timber houses next to each other. They are protected now, and perhaps that's the reason why the reoccurrence of those fires is so significantly smaller. Anyway, the hazard is not just in tightly packed timber spaces. It's anywhere where the wildland meets urban, hence the term wildland-urban interface.
Speaker 1:And with Wynne, one more challenge that comes in is embers. We've mentioned embers multiple times in this podcast, so let's try to define embers and risks and hazards coming from embers. And in this podcast. So let's try to define embers and risks and hazards coming from embers. And I actually had that done in episode 69 with Professor Michael Goldner, so I'll bring you back to him for explanation.
Speaker 2:Yeah, well, you know, take any campfire, blow really hard, you see little, you think a little sparks, but they're not sparks, they're little glowing embers. Just imagine now it's a forest and you blow the strength of a really strong wind and the size of those things coming off can be large, but most of the hazard is actually from smaller sizes, a couple centimeters in scale.
Speaker 1:Like a charcoal size.
Speaker 2:Charcoal and smaller, but somewhere between a large piece of charcoal and maybe a centimeter, because it needs to be big enough to still have a lot of energy when it lands and needs to be small enough to get picked up by the wind and blown ahead and and we can.
Speaker 2:That's, that's kind of how we figure out how far they're going to go as we find out this maximum distance for certain particles and you know those they're usually glowing, they can flame for a short period, but there's like short-range spotting. If you look at pictures from Australia, the bushfires, there's a lot of short-range spotting because eucalyptus are adapted to that and their bark can still be flaming and you'll see like flaming embers landing. But that's short range. The long range, the really dangerous, to start new fires, which we call spot fires, is typically by smoldering pieces. So that's the flameless combustion, like you're glowing, you're blowing on and it's getting like that and that stuff can pile up even in like crevices or on your deck or in the corners, um, and if that area is unprotected then it can start smoldering the wood in your structure and eventually we know that those fires you get the right blow of wind, you get the right conditions, you get them large enough, they transition to flaming.
Speaker 1:What distances are we even talking about? Like 50 meters, 100 meters, kilometer?
Speaker 2:Yeah, obviously it's a profile. A majority is probably within a few hundred meters, a few hundred meters, a few hundred, few hundred, okay but if you get a large enough plume, yeah, it's, it's far.
Speaker 2:If you get a large enough plume, if you get a fire whirl, if you get high winds, then it's kilometers. So a good general rule is about two kilometers. A lot of the observations of maximum spotting distance becoming less and less likely as you go out has been about two kilometers for spotting, but there have been reports of maybe tens of kilometers. It's probably rare, but that one rare fire makes a big difference. But it's been called a blizzard of embers. It is literally millions. They're everywhere and so we don't individually track. I mean, there are some studies individually looking at them. But we're looking at this broad swath of embers Stuff is flying everywhere and we're more thinking how far can it go? How far is it capable of igniting the stuff outside a house, a house itself, another forest fire? So how far is that? What's the probability that happens and how does that change with weather and other conditions? So that's usually the way we're looking at the embers and we still want to learn more about different materials, structures. Structures can also create embers that flies off them.
Speaker 1:And embers is perhaps the thing that I would need a separate podcast episode on. I've done research with Professor Guy Morin and a student, dr Simona Dossi, and Simona was looking into fire protection against embers and she's bringing some good ideas from the world of protecting against sand, so perhaps that's a topic for a future conversation in the Fire Science Show. Anyway, we've tackled when those fires can happen and how does it look, the conditions when the fires can happen. Now the question is can we predict them? That's a tough question and I've asked it in episode 117 to Albert Simioni.
Speaker 4:so let's go back to that it's difficult, even for other things right to see that for floods, hurricanes, even earthquakes. You know it's very difficult to prepare for something which is happening not very often, telling people hey, the next fire may be in 10 years or in 50 years, they will be okay, what can I do for that? And then you have a catastrophe like in Hawaii. So it's very difficult to prepare for that. And one of the problems we have with fire is that you know we're thinking about a house fire. We can put in place certain measures preparing for the catastrophe. You know you have your smoke alarm, you evacuate. You know, we know that your house will burn With wildfires.
Speaker 4:The problem is that the fuel is changing all the time. If you have no fires, you have an accumulation of fuel and you have to deal with that. And if your wind and urban interface is very big, then you have a lot of fuel to take care of, you know. And so we decreased the ignitions and we were telling people hey, look, there is a big risk of fire, don't do anything, and it's just waiting for the next ignition to get out of control with the bad weather conditions and it will happen. So, even acting on the ignitions telling people hey, today is a catastrophic fire risk, don't go in the forest, don't do anything. It's just delaying the inevitable, you know.
Speaker 1:While we were talking, I was wondering how long before you could actually issue a warning that it really looks like it's going to go to a catastrophic level before the fire ignites.
Speaker 4:In the US you have red flag warnings, for instance, and they're based on the methodology. So it's the drought index, so the condition of the fuel plus the weather conditions. It's the time you can predict the weather. So if you're lucky, two weeks, if you're less lucky, just a few days. But again, I think it's very important, how do you quantify your risk? That didn't happen.
Speaker 4:So if you're doing a good job basically at preventing fire, it's playing against you in a way. And we still have to understand the other benefits that we're having All the ecosystem services, all the things we're benefiting from living next to the forest, having a cabin in the woods or nature close to your house and everything. People don't give that very easily and anyway, with the big population, we're pushing people to these areas. I think a lot is really to be prepared and to try to be less vulnerable to that. But again, if it's happening every 70 years, how do you even invest your money and your time for something which will happen once in 70 years? And you know how people are If things go well, they will ignore you and then, if there is a big catastrophe, they will look for scapegoats and they will come after you.
Speaker 1:Just like Joe Rogan said, you can predict that fires can happen, but when and where. That's not a beast and that's very challenging. And also, when you give those warnings too often, the communities become insensitive to those warnings so they become less and less effective. Anyway, a very difficult thing to issue a good warning system. But the good warning system is really necessary. It's necessary so people can prep up their homes a little better. You know those last minute things that you can do to improve the chance that your home will survive an incoming wildfire. And another thing is to secure yourself, your loved ones, your animals, your wealth perhaps, and evacuate. And when it's very late to evacuate, those evacuations become quite a big problem and it's something also we've observed in the case of LA fires.
Speaker 1:So I would like to move a little bit to evacuation side of the wildfire science and I also had episodes on that. First Life had an episode with Enrico Ronchi and Max Kinteder. They are a part of WNIT project within Procurement London, nfp, rmit, and they have investigated community evacuations. They've actually participated in a community evacuation drill which we've discussed deeply in the podcast episode. That was episode 161. In that episode I've asked Enrico and Maxo about what's the difference between evacuating a community and evacuating a building, which probably most of our engineers would be familiar with.
Speaker 6:The scale that we talk about is completely different, but also the modes of evacuation are different. You know, when we look into buildings, we mostly look at evacuation on food, while instead, when we look at communities, we look at many different means of evacuation. So not only evacuation on food, but also using different types of transportation like private vehicles, public vehicles and also alternative means. Sometimes we've seen very, let's say, unique types of evacuation with boats or things like this. But in any case, I will say both the mode of evacuating is different as well as the scale, because even the largest buildings, in terms of population, we talk about thousands of people. I mean very rare. Okay, you need to have a massive high rise to have tens of thousands, but that's not super common While instead, when we talk about community evacuation, unfortunately it's more and more common that we talk about tens of thousands of people to evacuate. So to look into that kind of scale is a problem on its own.
Speaker 1:How about the timescale? Because, like in a building, I sound an alarm and hopefully after a pre-evacuation time distribution. Let's not go too deep into arguments about this, but after a certain amount of time I guess everyone left the building or at least started evacuating. Is the timescale also a differentiating factor in Wii evacuations?
Speaker 7:Yeah, I think so. One key difference is and you already mentioned that is that in a building evacuation you know like you hear the fire alarm and then it's go time right. Ideally, and unless it's an announced drill, no one expects a fire alarm to go off right. The difference for wildfires most commonly it's a seasonal phenomenon, so people are aware, like residents are commonly aware, of the risks of that wildfires might occur. In North America there's something called fire weather index, so there's some. So there's like public awareness that there's a big when there's an increased risk of wildfires.
Speaker 7:And also you have a little bit more lead way to evacuate. So, for example, if there's a wildfire in a proximity, you maybe maybe you don't get an immediate evacuation order, but you might get a notice that okay, maybe you will have to evacuate soon. So there's a little bit. The timescale is a little bit different. I think what's very interesting for us as researchers is that to see. So we come from the building evacuation side and we understand pretty well how people move around during evacuations and how they make decisions in buildings. What is really interesting to find out is whether those lessons translate to the WUI community.
Speaker 1:And how about safety? If I'm evacuating a building, I'm evacuating people to safety, which usually is outside the building or you know a designed area where people should gather. If I'm evacuating a hospital, I'm sometimes doing a horizontal evacuation. You know neighboring fire compartment. They're safe when they're in that space. Like, where do you evacuate those people? In a way, even how far you have to take them away to provide them safety, because I mean, the fire is a transient phenomenon that, in a way, is chasing them right.
Speaker 6:Yeah, well, and that's the challenge right, because we have seen in the past in different events that, for instance, people were initially evacuated in an area or in a shelter and so on, and then that very area became also threatened by the wildfire. So I would say that the challenge with the scale is not only the size in terms of area and number of people involved, but it's also to define in itself what's the threatened area, because this is kind of dynamic, so it's a much more dynamic process than what we are used to in buildings, where pretty much we know what are the spatial boundaries of the scenario that we're dealing with, while instead in a wildfire, we don't even know necessarily to begin with where, let's say, our evacuation war finished. And this of course has implications in design policies, even for all of us that use models and so on, because it's one of those key decisions that you need to take where to evacuate people and it's not obvious.
Speaker 7:Yeah so the question is often like what is a place of safety right? And that people and it's not obvious. Yeah. So the question is often like what is a place of safety right? And that's a broad idea and it can really change dynamically as the real convention. So one big challenge in wildfires is that smoke travels really far right and that can impact, for example, the vulnerable populations differently than people who are, who don't have certain risk and when the evacuation is covered really too late, we can call it a dire evacuation and this is a really, perhaps traumatic thing to most people that witnessed that.
Speaker 1:In episode 156, I've interviewed two researchers from Imperial College London, Harry Mitchell and Nick Karagopoulos, and they are developing technology to help us guide us better when it's the time to evacuate. They've called it trigger boundaries. Perhaps we'll talk about it a little bit more. Nick comes from Greece and he comes from a region which was struck with a very large wildfire, the Mati fire and he gave me a very good description of how evacuation looks like when it happens too late. So back to Nick.
Speaker 5:Yeah, this is unfortunate Talking about any. You know, delayed evacuation in a wildfire is not a pleasant story. In my case, I have family in mati, which was subject to the mati fire of 2018, with 104 people dead. Thankfully, everyone from my family is safe, but, you know, the house next to us is gone. House a few hours after that it's gone. There are, thankfully, not many people that we knew that were victims of the fire, but some people adjacent to us on the buildings opposite us did not make it. So we've seen the worst that can happen in a delayed evacuation. The worst thing that can happen is that people might just not know what is going on In Matti, in that area. I grew up there Even since I was eight or nine. I was used to seeing the sky turn orange, the firefighting helicopters coming down to the seaside to pick up water, so people were used to seeing smoke.
Speaker 5:And when there's smoke over your area, maybe you don't believe that it's a fire that's headed to your place, and in the case of Malta, so many things went wrong that people realized that they were in danger when trees next to them started catching fire because of firebrands. So the worst thing that can happen in delayed evacuation is that people don't know that they're in danger. And if you don't know you're in danger, you haven't made the evacuation plans and the architecture of the community such that most buildings have wooden roofs, which means that not make it a safe place to stay in place and avoid for it to pass. Then your only option is to try and evacuate. And if the road network is subpar and there is no coordination for evacuating cars, what can happen is a blockage, when either a car breaks down or there is no coordination for evacuating cars. What can happen is the blockage when either a car breaks down or there is too much traffic for the road network to handle, and not the moment one person decides to abandon their car and go somewhere else.
Speaker 5:In the case of Mati, run to the beach, that's it. The entire ingress route is blocked off and in Mati there was only a north and south route. Anyway, that can happen. Some people decide to stay in their cars because the smoke is way too dense. Some people go to the beach, but the smoke is still way too dense. So, yeah, delaying an evacuation can lead to tragedy, and most often does we refer to such phenomena as dire evacuations, when people attempt to evacuate without enough time to do so safely, and we see time and time again we saw it in 2018 in Mati, in the Camp Fire, in 2023, in the La Jaina Fire in Portugal, in the Pedro Gau Fire, in individual cases, in the Black Saturday fires in Australia. It happens time and time and time again. Circumstances are such that an evacuation either occurs or has to occur when there's not enough time to do so safely, either because of the strength of the winds, the dryness of the fuel or just the delayed process of starting the evacuation.
Speaker 1:I believe in the LA Palisades fire we've seen that. We've seen abandoned cars, we've seen people rushing out like really last minute when the fire came. Perhaps that's connected with the unbelievable speed at which the fire comes into the community, like in those Japanese urban fires. Perhaps not enough preparedness, perhaps not enough information. In any way, it was definitely a dire evacuation process. I mentioned Harry and Nick are developing technology to help us aid, so perhaps let's touch this technology a little bit.
Speaker 8:The overall aim of it is to inform, safer and more reliable evacuations. So around two to three percent of wildfires in the northern US, for example, spread into urban areas. And when a wildfire spreads into an urban area, stay put isn't always going to be the most effective method of defending the population. There will become a critical point where you might need to evacuate, but currently there aren't many resources or tools beyond firefighter intuition that define when is the time where we actually need to call an evacuation. So there's a lot of obviously there's a lot of research into wildfire spread modeling.
Speaker 8:So semi-empirical models like Farsight and Flammap and Prometheus, and the list goes on and on and on. And then there's a mountain of research into evacuation modeling as well. But the interaction and how to couple and interpret both of those phenomena together is heavily understudied and undercharacterized. So essentially, the point of trigger boundaries is to sort of bridge that gap to try and understand. Ok, when do we need to evacuate people so that they don't end up evacuating into or towards the fire, or before, how do we evacuate them before fire starts to impede the evacuation route?
Speaker 5:um, yeah, trigger boundaries came about when we were looking into how we can use, you know, engineering, mindset and mathematics to improve community fire safety. One of the things we found from, I think, professor Tom Kova, his team in the US was they used a methodology where they find an imaginary line around the community, to talk in fire safety terms, where R set equals A set. I'll explain for people that don't have a trying to approve document B. So it's a line where the available time to evacuate, dictated by the progression of the fire, is equal to the required time to evacuate for the whole community. So when the fire reaches this imaginary line around the landscape, the population has an exact amount of time to evacuate before the fire reaches them. If an evacuation happens before that line, then the entire community will have evacuated before the fire reaches them. If an evacuation starts after the fire has crossed this boundary, then there is a chance that people will still be in the community when the fire reaches them.
Speaker 1:I've said that in episode 156, I believe the trigger boundaries and the entire technology developed by the WinIT project is brilliant and can probably most likely will, save lives in the future. Anyway, as we reach the end of this episode, I wanted to bring a little bit on the solutions that I've done and most of my guests in each of those independent podcast episodes. Each of those guests gave me some ideas on how to protect ourselves, our communities, people at risk from this wildfire threat. I don't have time to bring all of those and I invite you to re-listen to those episodes. However, I can bring perhaps one interesting perspective brought by Michelle Steinberg and Birgit Messerschmidt from the NFPA, who are actually dealing with this particular problem, the political problem and how to actually improve the chances of our communities surviving and not having wildfires at all.
Speaker 1:And in that episode we've talked about not just what can be done, but what can realistically be done and what happens when people have to choose between safety and affordability. And also what happens when we rebuild the communities after the fires. How do we approach that. And if a community was struck with a wildfire, are we doing really the best job that we do to protect it from another wildfire. When you build at floodplains, you can expect a flood and perhaps you can protect your house from floods. If your house burned in a wildfire, it means that you are in a wee area and perhaps you can protect your house from floods. If your house burned in a wildfire, it means that you are in a wee area and perhaps you should invest in that, which is not always the case, but anyway, michelle will explain that much better than I do.
Speaker 3:You know, how can you say to people you've got to choose between safety and affordability? I mean, how can you do that? That's to me, very criminal. In other words, we want to house people but let's put them in high rises in an inner city that we're not going to do any kind of fire safety, we're going to let people just take their chances. To me it's the same in the wild and urban interface, where arguably many, many communities that are built there are more affluent and people think they're buying, they assume they have safety when they buy a home, you know, in these areas, especially if it's an expensive, nice area and they aren't getting safety and they have no idea that they're not getting safety.
Speaker 1:If money is the only issue, then let's find the money. I mean, I wonder if we are at the point where we could showcase a net gain on fireproofing or retrofitting buildings, because if you have fires that cost you $50 billion or whatever, if you have fires that shut down LaGuardia in New York, I mean costs are unimaginable. Of those, if you have $50 billion, you could protect quite a few houses in the US, I guess.
Speaker 3:Yeah, it's really interesting and that's, I think, the argument that we at NFPA, as advocates for fire and life safety and people in the industry, I think we need to be very vocal about that, because I get frustrated with and we've seen it happen. It's a very weird dynamic. So I'll give you the example of the Marshall Fire in Boulder, colorado. That happened at the end of 2021. They were all in a county called Boulder County, but there were three municipal jurisdictions, if you will. So there was two towns and then there was one part of the county that they call unincorporated. So the county has jurisdiction and one of the towns had already put in the books that any new construction will have residential fire sprinklers. Great, any new residential construction has fire sprinklers.
Speaker 3:Well, immediately, because they knew all these homes burned to the ground, there's nothing left. It's not a retrofit anymore, it's a new build, it's a rebuild they said, oh, we're going to waive that requirement, we're going to take that requirement away for these poor, poor people so they can rebuild their home and it won't cost so much. So, immediately, that decision putting that out there makes people think, oh, my God, it costs so much to build a home with fire sprinklers, and we know it is not. You know it costs something, but so much. And I said to one of my colleagues I said this is crazy. What's the next thing they're going to say we don't, we're not going to require proper electrical. He said, oh, they tried that they we're not going to require proper electrical. He said, oh, they tried that. They tried that all the time. They don't want to come up to the electrical code because it was just good enough. You know the way we were doing it and I'm like what century am I in? So they waived this and I thought so. Now you're putting people frankly it's substandard housing. It's substandard. It is no longer meeting a standard. You're putting people into housing that's less safe than their equivalent neighbors who are building new.
Speaker 3:I found that remarkable and, ironically, about a year later we found out there were people taking advantage, people who were having to rebuild a home, many people who did not have enough insurance to cover the total loss of their home. They were rebuilding taking advantage of some grants that were for what they call passive construction, meaning it was sustainable as well as safe, thick walls, et cetera. So less heating and cooling for the structure, et cetera, more energy efficient, because that was one of their values that they held dear was. I'd always hoped I could afford to live in a home that had these kinds of features. Now I'm getting some help and, yes, I'm going into debt over this because I didn't have enough insurance when my home burned down but I want this and I thought, wow.
Speaker 3:So when industries come out, I'll just say the building industry as a whole comes out and says it's too expensive to build these safety features in. I don't think they're listening to their customers. People actually want safety. They want sustainability. They want these homes that are taking up so much resources to be around for a long time. They don't want a disposable house okay, they want this to be around for a long time. They want to save energy. They want to live as lightly on the land as they can, reduce their carbon footprint, however you want to say it. So I get very frustrated when we isolate oh, sprinklers, that costs too much. Or proper electrical utilities cost too much. Or now it's oh, it costs too much to put a second staircase in a building of six stories, so please let us just have one. That's currently a huge issue for us in the United States.
Speaker 1:I think that's a really powerful conclusion for the end. If you were looking for the things that we can directly do to ensure safety and you're a fire engineer, you probably already figured out from this discussion. The combustible materials in the built environment. We need to limit that, guys. The spaces around the houses, they need to be managed. There has to be less pathways where the fires can cross from the outside to the houses, ignite them and participate in the fire Protection against embers. We need to make sure that there are no or less pathways in which embers can penetrate houses and in cases where you have a really dense architecture, dense built environment and possibility of strong winds, you really cannot have house touching a house, and all of them built in timber. That's going to end in an urban configuration. We all know that. I think the knowledge is there. It's just the execution that's lacking and perhaps politics that are difficult, and they're difficult for a reason, and those reasons were discussed in this podcast episode.
Speaker 1:Anyway, I brought you the collection of episodes on the wildland, urban interface problems and wildfires that happened in the Fire Science Show, so I would like to thank all the guests that gave me those interviews. I've learned a lot from them and I've learned even more when I revisited those episodes just right now. So just let me give the credits where credit is due. So just let me give the credits where credit is due. I've brought parts of episode 69 with Professor Michael Goldner, episode 117 with Professor Albert Simeoni, episode 156 with Harry Mitchell and Nick Karagopoulos, episode 159 with Michel Steinberg and Brigitte Messerschmidt and episode 161 with Enrico Ronchi and Max Kinteder. There were more episodes about Wildfires in the Fire Science Show, but I didn't want to take more than an hour of your time, so I've limited myself to those. And if you're looking for more information and more answers to the questions that appear, the answers are in those episodes and you are highly advised to go and listen to some of those.
Speaker 1:And the final comment on LA Palisades fires it was horrible. It's so sad when you see this happen and it's even more sad when you understand exactly how it happened. It's not that I could have predicted that this particular community will be struck by a wildfire this January, but you know that if you have a dense urban environment with combustible materials prevalent in your built environment, tightly packed in wind conditions in a dry season, it's to some extent inevitable, and I wish the politicians and people that have power to act could act on that. And those actions are needed on all levels, from governmental or state level, regional levels managing the wildland fires, managing the forest, having the water supply to battle the wildfires, having well-funded, well-managed, well-manned fire department that can react to communities, like looking at your individual house, looking at your neighbors, trying to protect each other, trying to work together. And also management of the risk. When the risk is unbearable, you don't need to wait last minute to issue evacuation. You should say what's the most valuable, and we heard those horrible stories of people who were left behind in those houses in Palisade Fire, and those, perhaps, are the ones that break my heart the most. We could have saved those people if our response was as it should have been.
Speaker 1:Fire science has a lot of answers. Fire science has built good understanding of the problem. Perhaps we don't have all the answers yet and there's definitely a lot of physics and a lot of phenomena that we need to study. We need to learn more about new building materials. We need to learn more about sustainability features and how they change the face of the problem, which they definitely do. But anyway, the WUI the Wildland Urban Interface Fire Problem is recognized today. We know a lot about it and there shouldn't be fires like the one that happened in LA, and I hope experts like the ones that I've brought in today and all my colleagues who are working in the space of wildfires, together we can create a safer world.
Speaker 1:Thank you for listening to this podcast episode. I hope you've enjoyed the format of bringing up some most important parts of previous podcast episodes. This kind of narrated style of podcast is also something I do in my second project, the Uncovered Witness, where we've discussed evacuation at large, and we've also recently covered the building defects and some interesting lawyer insurance stuff that what happens when there's an issue with fire protection of a building. Perhaps you would be interested in that. If you've enjoyed this episode, you will definitely enjoy uncovered witness and if you are a fan of fire science show, you know what happens next, next wednesday another great episode for you. So I looking forward to see you then and thanks for being here with me today. Cheers, bye. Thank you.