(pensive music) - They're extreme events because they don't, in theory, they don't happen often.

- Largest piece of hail recorded in the state of Alabama.

- There is no prototype.

We build the building and it has to perform correctly.

- There is this way around it.

- You shake it and see what happens.

- Geotechnics is saying, "Hey, we can be smarter than this."

- Geez, my God!

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- Isn't it creepy when solid ground gets mushy?

- Or when a nice, fluffy cloud rains down frozen rocks?

- It's comforting to think that the world is static and that things make sense and they stay put.

- But the science of homes and of the universe is dynamic.

It's ephemeral, which is a beautiful word that means temporary.

- Let's dig into the Earth-shaking physics, chemistry, and microbiology of the ephemeral world.

(gentle, dramatic music) - [Narrator] It's the shields we build and the risks we take.

It's the disasters that will test us and what will grow from them.

It's real life and the physics, chemistry, and microbiology of the science of homes.

- The natural world is very active.

Under the ground, there's earthworms that are tunneling through the soil.

There's water moving through the soil.

There's gravity acting on the soil that's slowly pulling the soil particles along.

(pensive music) Sometimes this happens over hundreds or thousands of years, and sometimes it happens over timespans of tens of seconds.

- When we study community disaster resilience, extreme events are a big part of that and they're extreme events because they don't, in theory, they don't happen often.

But what we're seeing is that they're happening more and more often.

But they're extreme, too, because they're above what we specify in our building codes.

So our building codes give design loads and minimum requirements that we have to legally build to, and that's when and where building codes are even adopted and enforced, which is a problem in and of itself.

- At the moment, a lot of hazards researchers work in the areas of earthquake.

In fact, we have a pretty good handle on how to design buildings to resist earthquakes.

- So when we build buildings, single-family or multifamily homes, in order to make sure they're safe, you can overdesign, make it very beefy and strong and say that's enough.

Or you can try to optimize that.

We have building codes that engineers follow and we are constantly trying to make adjustments and updates to these building codes as the knowledge increases.

You know, computer models are great and that is what engineers do use in the real world to design things.

But there's only one true way to know how something will perform during an earthquake, and the only way you would really know is if you shake it and see what happens.

This shake table is one of a kind.

It's the largest outdoor shake table in the world with the highest payload capacity.

Since we're outdoors, we don't have height restrictions, so we can build large specimens such as the 10-story building that we're currently in the middle of testing.

So when an earthquake occurs, single-family homes typically don't see too much damage.

Multifamily homes, however, they're more interesting.

They're generally taller buildings, much more units, more rooms, more space, more column beam connections, et cetera.

What happens to a multifamily home during an earthquake is we need to evacuate the building.

The goal is for that building to stay, you know, standing long enough to allow for people to evacuate that building.

Ideally, it would have damage that's easily repairable so you can reoccupy it rather quickly.

In some cases, the damage is too extensive and, you know, those people will be displaced for a while.

That's obviously something we'd like to avoid.

(pensive music) We've seen certain buildings perform better in earthquakes.

Buildings made out of timber generally perform pretty well during earthquakes due to their flexibility.

They're a little more flexible and forgiving.

You need to have a certain amount of flexibility to move and sway with the earth as it's moving.

- Earthquakes are waves but with different amplitude and different frequency.

And the source, of course, is different, but again is another type of wave.

Instead of talking about a house, we talk about, for example, a breakwater.

The same concept is applied.

Breakwaters are supposed to be a very rigid structure that supports the action of waves and they supposed not to move, not even the individual rocks that you see in breakwaters.

So they are fixed and rigid, similar to the concept of a building that is not responding to earthquake.

There are breakwaters that are called dynamic breakwaters or berm breakwaters that are designed to move with the waves and change its shape and adapt its shape, so the profile of the breakwater dissipates better the wave energy.

That was allowed to be flexible in the same as the houses that are flexible in earthquakes.

- Through some testing and experimental work done, actually, here, at this shake table in San Francisco, there was a huge retrofit effort for soft stories, where you would have an apartment building and you'd have right under it, there'd be the parking for the cars, like the carports.

And the very bottom floor is very flexible and can, you know, tip over and just pancake down, squishing that first floor where the cars are parked.

So earthquakes can cause a lot of damage, not just to the building collapses or bridge collapses.

They could take out power lines or they can burst pipes and you wouldn't have any gas or water.

Even sewage can become a problem if it starts to contaminate the surroundings, for example.

That could be devastating, more so than even the building collapsing, 'cause the effects can be longer term.

- A lot of hazards research is performed in laboratories,, but in laboratories we can't test full-scale buildings.

On the shake tables, we can test a model of a building and maybe getting close to full scale, but it's still just a portion of the building.

It's impossible to test the entire structure.

Whereas, if you think of aeronautical or mechanical engineers, they can build a prototype and they can run it through thousands of different tests and make sure that it works.

Civil engineers, structural engineers, design and build buildings that are once-off.

There is no prototype.

We build the building and it has to perform correctly, or we build the bridge or the dam and it has to perform.

There's no practice.

By doing field reconnaissance after extreme events, if we understand the hazard, if we have a measure of the wind speed or the water flow velocity during a flood or the earthquake from seismometers, we know what the hazard was and we know what the building was subjected to.

Now we can look at the performance of that building at full scale and compare it with what we saw in the laboratory and make sure that what we derived from the laboratory experiments is in fact correct.

- [Engineer] The model we put out here is the size of a small car.

It's 5,000 pounds and then we put this thing in.

It is going more than 200 miles an hour around the perimeter of this room.

- [Interviewer] Amazing.

- [Engineer] If you could imagine NASCAR racing in a room that was a 60-foot diameter.

(pensive music) - The challenge with doing any kind of physical experimentation with soils is that soils are really heavy.

When you wanna build something like a large embankment, make it 50 feet high, 100 feet high.

We can't take something that heavy and put it on a shaking table.

So maybe we make an embankment that's only two feet tall.

Small models don't give us the right physics, the right understanding of the soil behavior.

Now, there is this way around it, and that is dependent on gravity.

If I take that model and if I increase gravity, I apply 50 times Earth gravity, now the weight of that soil is two feet of soil times 50 gravities, and the stress now is equal to 100 feet of soil at one gravity.

(centrifuge roaring) - Geez, my God!

- I think what's unique about geotechnical engineering is that our building material is nature itself.

It's the soil, it's the rocks, and on top of that the materials we use vary all the time.

So every project site we go to, the subsurface conditions are different.

And if you compare that to concrete, steel, water, a lot of the other building blocks, if you will, of civil engineering, geotechnical engineering I think is particularly unique, because we have this tremendously variable material built and placed by nature.

And the question is: how can we work with it?

How can we work around it to use its strengths and at the same time don't create negative consequences and help society live in that environment using and living on top of nature in a really healthy way?

(pensive music continues) - If you stand at the water line on a sandy beach and you shake your feet, the sand can get very, very soft.

This is something we'll call liquefaction.

Just think of the soil getting very soft and and fluid and shifts and moves around.

You shake 'em during an earthquake, some soils can lose their stiffness, lose their strength.

And, of course, if you then stood on the sand, it can stiffen and carry your load again.

So it doesn't mean that the stuff flows like a quicksand.

What it means is it can look like a liquid temporarily and it can move and deform even if, later on, it stiffens back up again and supports structures.

It turns out that one-way waters deposit soils, so running rivers or estuaries, wind-blown sands.

When they are younger deposits they are often looser.

And this is also true for any kind of man-made deposits, hydraulic fills, dump fills, where people have developed land around margins of bays or expanded out into deltas, et cetera, the soils as deposited are relatively loose.

Sometimes we see flow liquefaction after earthquakes, where the soils lose so much strength, we have the collapse of the banks, collapse of levees, of structures that settle into the ground and tip over.

They can be very dramatic, but just as bad is when the ground only moves moderate amounts.

If the ground moves a foot or two feet, that can be more than enough to break all the utilities in the ground.

So liquefaction doesn't have to be dramatic in terms of things flowing and collapsing to be extremely damaging to our communities and our infrastructure.

Now, these types of materials are often mapped and well-recognized.

You can find regional mapping.

Now, you can't tell just by looking.

The ground can be quite stiff and strong just sitting there today, a good foundation material.

So the question is how is it going to behave under the cyclic loading of an earthquake?

The soils can be saturated, in part, by just having a naturally high groundwater level near a body of water, a bay, a lake, a river.

We don't wanna give the impression that all ground is liquefiable.

You can have very dense sands and gravels and all kinds of soils if they're dense enough, if they're old enough.

We have lots of sites after a very strong earthquake where the ground doesn't deform.

There are definitely places where the ground conditions are good and can support structures through these types of hazard loadings, including earthquakes.

Are we being wise in where we're developing our communities?

That is a very difficult topic, because that is a societal decision.

Now, certainly it would be easier engineering-wise if we weren't building in floodplains and we were avoiding areas where we have pervasive liquefaction risks.

But at the same time, there are also ways that we can design our infrastructure to better tolerate some of these pervasive problems.

And so there can be a balance.

(chill music) - So landslides are first off a natural phenomenon.

We kind of oftentimes in engineering talk about slope failures.

I kind of shy away from those words, because it doesn't really respect the fact that we have active processes that are taking place outside the window right now.

Not necessarily that the ground is slipping away at this instant, but landslides shape the Earth's topography and they, in a sense, are the reason why we have topography and why it's ever-changing.

Landslides are in a very general sense the downward movement of the ground surface, often in response to heavy rainfall events, often in response to earthquakes, and sometimes without any apparent precursor.

They affect all states in the U.S.

They are a worldwide phenomenon.

They're responsible for tremendous losses in a lot of residential.

They're also responsible for loss of life.

There's different types of landslides.

Some are very slow moving, and those are the kind that don't pose a significant hazard to people.

And it's important to discern between that and a fast-moving landslide.

A fast-moving landslide can unfold in a matter of seconds and it can move a mile or more.

An example of this was the tragic landslide in Oso, Washington that killed 43 people.

It was a fast-moving landslide that inundated that community on an order of about 20 or 30 seconds.

Slow-moving landslides typically move as coherent masses and slow accumulation of damage.

There's ways of finding these.

When you go to a doctor and they'll tell you to look at your skin for any kind of changes between visits.

I like to tell homeowners to do the same kind of thing with their properties if they're living in areas with some kind of slope to the ground surface.

If you're in that setting, take a look around and get to know the land surrounding your house.

If you see changes to that ground, if you see cracks opening, if you see bulges forming, you probably have a slow landslide that's in process.

There's things you can do to arrest them once they're in motion, and they are, in a sense, precursors for continued movement.

Fast-moving landslides often come without warning.

Sometimes there's small precursory movements, but often they happen so quickly that people don't have a chance to escape.

They can move at speeds of 25 miles per hour.

There's measures you can take if you sadly find yourself in that situation, and hopefully you don't.

You can go to the second floor.

We found that people are much safer upstairs than being downstairs.

You can move away from the landslide.

A lot of times bedrooms are situated facing the up slope, facing the hill.

Those tend to be dangerous places for people to be sleeping.

When there's been an extreme rainfall event, it might be an elevated risk for a fast-moving mud flow-type landslide.

There's a whole range of sinkholes.

Some of them are anthropogenic, they're made by people.

And so examples of sinkholes made by people are us tunneling into the ground and having a tunnel collapse.

A lot of these are related to old areas where we used to mine underground.

So we've taken out some of the rock or some of the soil underground.

A lot of these have been long abandoned.

They eventually collapse and a sinkhole opens.

There's a lot of natural reasons that we have sinkholes, as well.

There's places like Florida, for example, that have what's known as karst terrain, where we have limestone, which is a rock that can dissolve in water, not over the course of days or weeks, but really over geologic time, over hundreds or thousands of years.

As that rock melts away, it can slowly form sinkholes that then open up at the ground surface, many times catching people by surprise.

(pensive music) - So we make and shoot hail at different building products in this lab to figure out, you know, how does it stand up?

From the aging farm, we actually go out and cut the panels out and we bring 'em in here to the laboratory.

So at 5, 10, 15 years, we can test again.

And so the things that I have here on the table are 3D-scanned, actual hailstones.

Largest piece of hail recorded in the state of Alabama.

And when you study hail and people start talking about it, they start saving it for you.

So that one actually has the right mass of a hailstone.

- [Interviewer] Yeah, it feels significant.

- Fortunately, most of the hail that does fall from the sky is more like that one.

Terrance has shot more hailstones than any person on this planet.

- Really?

- Absolutely, he shoots lots of building products.

We've already done a bunch of five-year panels and the hail performance in particular, you see a lot more granule loss at the five-year panel.

- [Terrance] Yep.

And press fire you when you're ready.

- And I'm ready for fire.

(device fires) (interviewer shrieks) - Yeah, and you can feel the impact.

- Can feel... Oh my gosh, yeah, that's quite a dent.

- I know this show's largely based on science and things like that, but, you know, when you have a roof leak, it doesn't necessarily express itself inside the house right away.

It takes time sometimes.

And, you know, you may be dealing with an elderly person who doesn't look up a whole lot, and maybe it took 11 months for it to finally express itself inside.

And most policyholders don't get on the roof and walk around after a storm.

(pensive music) Things that a policy holder should do all the time following a disaster or any type of loss that you're gonna need to report to your insurance company, the first thing you need to do, you need to comply with your post-loss obligations.

Find 'em in your policy.

You're gonna give prompt notice of your loss.

And by prompt, what I'm gonna say is immediate.

Don't delay, just go do it.

Don't wait.

I've seen where insurance companies will say, "Oh, you waited four days to report the loss.

That's unreasonable.

We're not gonna pay for your claim."

You're gonna protect your property from further damage.

So if you've got a roof leak, you need to put a bucket down, you need to put a tarp on the roof, you need to do something.

Document, keep receipts, take pictures, take videos.

You're gonna need to show the damage to the insurance company.

So if they want to come inspect, be nice, let them come inside, they need to see it.

If you don't show them the damage, then they're gonna say, "Well, you denied us access.

We're not paying."

So when an insurance company decides to hire an engineer, "Okay, we're getting a professional engineer, this is gonna be good, because certainly this guy went to school for a long time, he knows what he is looking for, and is gonna see the damage and he's gonna tell my insurance company that this is what he sees and they're gonna pay."

But that's not always the case.

They're hoping the engineer can give them an out.

They're paying an engineer thousands and thousands of dollars to try and figure out a way not to pay your claim.

Maybe they can call it wear and tear or long-term damage.

They're hoping that engineer can point the finger somewhere else.

So that's kind of one tactic that you see time and time again, where the damages are just so obvious but they'll send out an engineer where their company gets 95% of their business annually.

So yeah, if they get an engineer, often, you need to make sure you have an engineer as well, which just makes everything more expensive.

I have no doubt that there are probably plenty of times where the right thing happens.

But unfortunately, with my line of work, I see a lot of what it looks like when they don't do the right thing.

Generally, operate in good faith when you deal with an insurance company.

Wear the white hat.

Even if they're nasty to deal with from time to time, just do the right things and comply with your duties and your policy and things will usually fall into place.

- There is no such thing as a natural disaster.

The disaster is human-induced by the way we build and by the way we live and where we live.

If a natural hazard happens where a community is resilient to that natural hazard, nothing happens.

Everybody survives.

There's limited damage.

That's not a disaster.

A disaster is the confluence of a natural hazard with an unprepared community.

(pensive music) - Over about the past two decades, geotechnical engineering, you could say, has undergone another kind of transformation.

1930s, 1960s, we just started understanding a lot about the physics and the interaction between particles.

You turn to the 1960s, 1980s and that was really the advent of understanding that there's a lot of chemistry going on.

And some people would say that, over the last maybe 20 years now at most, the role of biology in geotechnical engineering has kind of been the next advent of our profession in a way.

It really came down to people scratching their heads and being confounded at having observations in the field.

And we just simply couldn't explain what was going on based off of what our knowledge base was.

And people said, "Hmm, microbiology must be at play.

There must be organisms doing something to the ground, which we've never thought about."

So most of the time, nature and biological systems, they're really constrained by trying to survive and doing it really efficiently with a minimal amount of energy.

So an example is microorganisms, bacteria essentially, in the soil, and there's a lot of them.

I mean, even in our sandbox sand that we play with, there's more organisms in a gram of sand than there are in the population of the U.S. Let's learn what they do, let's see if it's beneficial, let's learn to harness it, and now let's change the soil properties by having them do it for us.

One great example of this, an area I've been involved, in is calcite precipitation.

(pensive music) You can stimulate the native bacteria, they become active, and then you can provide the nutrients and the chemicals necessary.

And basically, they can take loose sandbox sand and in a matter of a week or two, they can change it into a sandstone kind of material, which is hard.

It's no longer liquefiable, it no longer flows.

You can make a column of it and you could stand on top of it.

And a lot of people are looking at that for a lot of different applications.

So that's bio-mediated, and that's one half.

The other half that has emerged more just in the last decade is bio-inspired.

Bio-inspired is maybe not as common of a term as biomimicry.

The idea behind biomimicry is you see something in nature, you copy it, some aspect of it, and then you have something that kind of looks like nature, but it does something you want it to do.

We pulled about a dozen different trees, all three years old, from the ground surface.

And we saw stark and significant differences between the capacity of those different trees when you pull them out of the ground.

And you talk to the farmers and they would say, "Yes, this tree is best in high wind conditions."

But from a geotechnic, like an engineering perspective, we never really understood it.

What's the architecture of the root systems, and which aspects of the architecture matter for the structural performance as opposed to mattering for water uptake, for example.

And so in both cases, both bio-mediated and bio-inspired, because they're both driven by nature, the solutions we're starting to come up with in biogeotechnics is more efficient, more cost effective.

It'll be more sustainable than what we do right now.

And for some context on that, what we do right now largely came from just heavy construction practice.

If you go back 1950s, 1970s, what did we have a lot of?

We had a lot of concrete, we have a lot of fossil fuel, and so we can just mix cement in anywhere.

We can pound things in the ground relentlessly.

Geotechnics is saying, "Hey, we can be smarter than this."

So we've learned some new things that we never would've guessed or predicted by spending some time studying nature before we would go about our conventional geotech work.

- Really what it comes down to is we learn, we continue to learn from earthquakes.

The whole international community works together so that we can better prepare for future extreme events, but also, how can we recover?

How can we make these things easier to fix?

And that's the idea of resilience of a community, how quick you can rebuild and get it going.

(pensive music continues) - You know, it's amazing to me that even with all this groundbreaking science, we still have a long way to go to help people understand how to use it to make their homes safer and more durable.

- Some of the most misunderstood pieces of the puzzle will be our focus in the next episode, all about sick building syndrome.

- To learn lots more about this and all the &other science in our show, visit homediagnosis.tv.

Tune in next time.

(pensive music continues) (pensive music continues) (pensive music continues) - [Announcer] "Home Diagnosis" is made possible by support from Broan NuTone.

Better air.

Better life.

By the "got mold?"

test kit.

Real science, real simple.

By AirCycler, Retrotec, Rockwell, and RenewAire.

By generous support-