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Hello everybody, welcome to the Fire Science Show.
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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.
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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.
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I really like to to provide this type of overview of what happened from from the perspective of science.
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And recently.
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Recently, we had a massive fire.
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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.
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It's definitely a massive tragedy.
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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.
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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.
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And in fact, as the podcast goes.
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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.
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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.
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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?
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And then I thought you know what A lot has been already said.
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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.
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So in this podcast episode I would like to take advantage of the vast library that Fire Science Show has created.
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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.
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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.
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So please join me on an episode with the fire science on the science behind wildfires.
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Welcome to the fire science show.
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My name is Wojciech Wigrzyński and I will be your host.
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This podcast is brought to you in collaboration with Ofar Consultants, a multi-award winning independent consultancy dedicated to addressing fire safety challenges.
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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.
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So Joe Rogan predicted Palisades fire.
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That was the thing that was trending on my ex, or Twitter, or whatever we call it today.
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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.
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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.
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It's just it's very hard to say exactly when it will happen and where exactly in the world will it happen.
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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.
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Maybe it will never happen, maybe it will happen in next week.
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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.
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In fact, indeed, those fires could be inevitable.
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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.
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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.
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So once we understand that, we perhaps can put some measures to protect us, we know that we can put those measures.
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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.
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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.
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And also media attention often is on the ignition source.
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You know why it ignited.
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Was it an electricity line?
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Was it an arson?
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Was it someone having a campfire at the edge of the forest?
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I don't like to put focus on the ignition, because if the circumstances are correct, the ignition is irrelevant.
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It will eventually happen.
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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.
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This, I believe, is the fire engineering way.
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Anyway, let's try to define the wildlife-urban interface fire problem.
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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.
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But here we focus mostly on really the urban interface.
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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.
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We will talk about the contributing factors and the community resilience and we're going to talk a little bit on evacuation as well.
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So a lot to unravel, but I think it's a good high level overview of the problem.
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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.
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I also had an episode on wildland industry interface.
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But here I would like to revisit episode 69 that I had with Professor Michael Gollner from Berkeley, california, whose authority in wildfires.
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He gave really good talks on television after the Palisades fire from Berkeley, california, whose authority in wildfires.
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He gave really good talks on television after the Palisades fire.
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So you probably could also revisit them to get a very short, sharp commentary on what happened.
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But anyway, in episode 69, I've asked Michael what is the we problem?
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And perhaps before we talk about it in depth, let's try to define it.
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Some of the definitions are a bit loose and it depends on where in the world you are.
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We don't even call it wildland-urban interface.
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We don't even call it wildfires.
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Down under in Australia you call it bushfires.
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But it's generally the burning vegetation and natural materials, undeveloped land.
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That's a wildland fire.
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It could be a forest, grassland, shrub, chaparral, but when it meets developed areas there's this interface.
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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.
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I like to define it that it's not just the area where it meets but the area that can be affected.
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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.
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This wildland urban interface often starts from the vegetation or the forest or whatever it is, and spreads.
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How it differs from the normal problems you would have in your, let's say, house or whatever building you're designing.
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I guess the first thing is the threat comes from outside, but probably there's more to that right.
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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.
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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.
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But any of these mechanisms spread that fire from the outside into your home and the investigations into wuyi fires have been really interesting.
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See just just how that spread and how the dynamics are different.
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Inside a house we're so compartmentalized we either have we might have sprinklers to contain the fire.
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It doesn't put it out, it contains it within a room.
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But our rooms have, you know, drywall covering.
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We have doors and there's fire doors.
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Right, we try to contain the fire to its origin.
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Here.
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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.
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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.
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You get one ember inside and then, with no one there, the home burns down and so there's wooey.
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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.
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That's exactly how we see the damage.
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The houses burned down not because of insane heat from the exterior.
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They burned down because they've ignited and eventually each of those houses, at their individual level, underwent a fully developed residential building fire.
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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.
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Actually, in that episode, the main subject of this episode was to actually grasp what is the WE problem.
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That was the main subject of this episode was to actually grasp what is the we problem.
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That was the whole idea of the episode, but I think Michelle gave me a very good description.
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That's a great addition to the definition that Michael just brought in.
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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.
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So we're trying to draw a line.
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When you say interface that you assume there's sort of a line or a barrier or boundary.
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That is a nice neat definition for a very messy problem.
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The messiness comes when we're talking about what is causing the fire.
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So that wild land word gets in there.
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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.
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What is even wildland?
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We don't understand what that means, first of all.
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And then urban also has its own connotations of a city and people think, well, cities don't burn down from wildfires.
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So what are you talking about?
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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.
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So it doesn't mean that our commercial buildings are so well built.
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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.
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Even the word wildfire has its own set of definitions.
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But the presentation and why people get so confused is when we go beyond the sort of the why are things burning?
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How are things burning?
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Which is our sort of scientific question.
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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.
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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.
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And we find over and over again that those definitions don't make sense in real life.
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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.
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So it's really ironic that we have people running away from and towards this definition.
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That in and of itself is not very helpful to describe what the problem is.
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I've brought that part because Michelle shows how fluid the problem is like.
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What is the wildlife urban interface and how to define it?
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And on one hand you could just go with a broad definition anything that can be at risk from a wildfire.
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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.
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So we're trying to put a very rigid definition on a very fluid problem, and that's perhaps a part of the issue.
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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.
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Is that a good definition?
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That means like half of the planet is in a wii.
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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.
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So that definitely is a challenge, a political challenge and also a challenge for fire science.
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How do we define those who are at risk?
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You know if joe rogan could define palisades and being at risk or la being at risk.
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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.
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But the risk is also multifaceted.
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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.
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So let's talk perhaps a little bit on the physics of those fires.
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What are the contributing factors?
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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.
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Is this dryness the reason we have fire seasons?
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Are they always connected with the summer?
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I mean, right now it's not a summer on the Northern Hemisphere and we just had a massive fire.
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Yes, it's driven by the vegetation.
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I mean, right now it's not a summer on the Northern Hemisphere and we just had a massive fire.
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Yes, it's driven by the vegetation, of course, the immediate conditions at the time of the fire.
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If it's raining that day, there will not be any fire but it's triggered by the trend in the vegetation.
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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.
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Actually, in the northeast of the American continent the fire season is in spring.
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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.
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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.
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Then when the summer comes, it's humid and it's not very flammable anymore.
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So now the eastern shore of the American continent is pretty humid, you know.
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So the fires move to west, where it's more like following the Mediterranean pattern than you need the summertime to have things dry.
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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.
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I believe that was last year.
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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.
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But if you look at Hawaii.
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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.
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So on one side, on the eastern side of the island of Maui, you have the rainforest.
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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.
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But again, grass burns and it's not something that people will make the news.
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You know grass is burning all the time.
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What you need to have that in the news is you need that to impact people.
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And so the grass is igniting the first houses and then the first houses burn.
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And there is a big wind because it's coming down from the mountains and you have this effect.
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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.
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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.
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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.
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And that was an important point.
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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.
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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.
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So let's bring Michelle Steinberg once again on secondary ignition items.
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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.
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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.
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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.
00:22:40.134 --> 00:22:50.886
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.
00:22:50.886 --> 00:22:56.449
That's what they have control over usually, and they can't control the wind, they can't control the national forest.
00:22:56.449 --> 00:22:59.096
You know, a mile down the road they can control.
00:22:59.425 --> 00:23:00.709
What does my roof look like?
00:23:00.709 --> 00:23:03.557
What does the vegetation look like right around my house?
00:23:03.557 --> 00:23:12.854
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.
00:23:12.854 --> 00:23:14.887
So that's getting down to that micro level.
00:23:14.887 --> 00:23:19.509
And then, oh, by the way, if my neighbor's closer than about a hundred feet, I have to worry about them.
00:23:19.509 --> 00:23:26.051
And so we start to get people to work with their neighbors to reduce those potential fuel sources for ignition to homes.
00:23:26.993 --> 00:23:31.874
You also mentioned those secondary items, trucks and everything that you can have outside of your homes, right?
00:23:33.406 --> 00:23:35.652
Fences, flat wooden decks.
00:23:35.652 --> 00:23:49.848
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.
00:23:49.848 --> 00:23:50.691
So it is.
00:23:50.691 --> 00:23:56.675
That pathway of the fire spread are again things that now scientists are looking at much more carefully.
00:23:56.675 --> 00:23:58.766
Because we've already solved for the radiant heat.
00:23:58.766 --> 00:23:59.528
We already get it.
00:23:59.528 --> 00:24:04.605
Okay, we don't want big flames near our house Cool, we can usually accommodate that.
00:24:04.605 --> 00:24:14.593
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.
00:24:14.593 --> 00:24:33.276
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.
00:24:33.316 --> 00:24:35.567
We work with the communities, we work with the fire service.
00:24:35.567 --> 00:24:42.892
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.
00:24:42.892 --> 00:25:00.882
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.
00:25:00.882 --> 00:25:17.417
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.
00:25:17.417 --> 00:25:22.396
That's one of the first things they're going to do is get rid of that link from the fire to the house.
00:25:23.305 --> 00:25:31.672
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.
00:25:31.672 --> 00:25:42.212
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.
00:25:42.212 --> 00:25:51.413
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.
00:25:51.413 --> 00:26:01.692
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.
00:26:01.692 --> 00:26:05.987
So anyway, giving the air back to Mike Goldner from episode 69.
00:26:06.387 --> 00:26:11.790
If you just have a small fire, a fire department can respond, put it out or they can protect the homes.
00:26:11.790 --> 00:26:14.743
But that's what's different in the wild and urban interface.
00:26:14.743 --> 00:26:17.391
You're not talking about two structures, three alarm fire.
00:26:17.391 --> 00:26:26.653
You're talking about maybe, let's say, 10 kilometer wide fire front spewing embers two kilometers ahead of the fire.
00:26:26.653 --> 00:26:30.098
So you got a huge area all being impacted.
00:26:30.098 --> 00:26:32.689
How many thousands and thousands of homes.
00:26:32.990 --> 00:26:52.994
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.
00:26:53.576 --> 00:26:56.666
You need enough vegetation and wildland fuel to ignite.
00:26:56.666 --> 00:27:03.268
And then you know, in some ways, our community is now a target, so you need a target that's receptive to a hit.
00:27:03.268 --> 00:27:18.487
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.
00:27:18.487 --> 00:27:35.953
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.
00:27:35.953 --> 00:27:46.920
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.
00:27:46.920 --> 00:27:49.643
Their only responsibility is saving lives.
00:27:49.643 --> 00:27:57.249
They're no longer doing structure protection, there are no resources, and so that's the epitome of the ultimate disaster scenario.
00:27:57.869 --> 00:28:11.909
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.
00:28:11.909 --> 00:28:18.709
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.
00:28:18.709 --> 00:28:34.319
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.
00:28:34.319 --> 00:28:37.595
So I'm very, very familiar with how these winds look like.
00:28:37.595 --> 00:28:42.857
But it's not just the wind that creates these extremely hazardous, disastrous conditions.
00:28:42.857 --> 00:28:45.753
It's also the way how the community was set up.
00:28:45.753 --> 00:28:49.836
And I'm not very familiar with L, with LA, and I've never been there.
00:28:49.836 --> 00:28:52.773
But I've seen pictures from the palisades.
00:28:52.773 --> 00:29:04.032
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.
00:29:04.032 --> 00:29:17.065
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.
00:29:17.065 --> 00:29:31.441
So you have an extremely tight built environment with tons of presumably timber buildings that are surrounded by vegetation that altogether is very dry.
00:29:31.441 --> 00:29:42.935
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.
00:29:43.224 --> 00:29:57.726
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.
00:29:57.726 --> 00:30:16.356
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.
00:30:16.356 --> 00:30:33.114
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.
00:30:33.114 --> 00:30:36.934
There have been hundreds of fires in Japan like that.
