Improving earthquake risk maps, and the world's oldest ice

This episode delves into recent advancements in seismic hazard assessments and explores the discovery of the world's oldest ice, shedding light on past climate conditions.

1. Modern seismic hazard maps tend to overpredict earthquake intensity compared to historical records.
2. The world's oldest ice, found in Antarctica, contains valuable climatic data from six million years ago.
3. Advances in understanding mosquito repellents through microbial engineering could lead to long-lasting, non-chemical repellents.
4. Conservation efforts globally are showing positive impacts on biodiversity and ecosystem restoration.
5. The episode highlights the importance of interdisciplinary research in understanding and solving complex environmental and geological issues.

1. Introduction

The hosts introduce the episode's topics, including earthquake risk maps and the discovery of ancient ice.
Sarah Crespi: "Today, we're diving into how past data enlightens current science."

2. Seismic Hazard Maps

Discussion on the research by Leah Saldich, which evaluates the accuracy of seismic hazard maps using historical earthquake data.
Leah Saldich: "We've discovered significant overpredictions in seismic intensity by current hazard maps."

3. World's Oldest Ice

Exploration of the significance of the oldest ice found in Antarctica and what it reveals about past climate changes.
Christy Wilcox: "This ice is not just old; it's a time capsule from six million years ago."

4. Mosquito Repellent Research

Insight into new research on using engineered skin microbes as a sustainable mosquito repellent.
Speaker D: "These engineered microbes significantly reduce the attractiveness of hosts to mosquitoes."

5. Conservation Efforts

A review of a study that assesses the effectiveness of global conservation efforts.
Christy Wilcox: "The positive outcomes suggest these efforts are not just worthwhile; they're essential."

1. Consider using non-chemical mosquito repellents that leverage advances in microbial engineering.
2. Support and advocate for continued funding and research into seismic risk assessments to enhance public safety.
3. Engage with community and global conservation efforts to help reverse biodiversity decline.
4. Educate others about the importance of historical data in refining modern scientific models.
5. Stay informed about scientific advances that can directly impact personal and community preparedness for natural events.

Bringing historical seismic reports and modern seismic risk maps into alignment, and a roundup of stories from our newsletter, ScienceAdviser

First on the show this week, a roundup of stories with our newsletter editor, Christie Wilcox. Wilcox talks with host Sarah Crespi about the oldest ice ever found, how well conservation efforts seem to be working, and repelling mosquitoes with our skin microbes.

Next on this episode, evaluating seismic hazard maps. In a Science Advances paper this week, Leah Salditch, a geoscience peril adviser at risk and reinsurance company Guy Carpenter, compared modern seismic risk map predictions with descriptions of past quakes. The analysis found a mismatch: Reported shaking in the past tended to be stronger than modern models would have predicted. She talks with Crespi about where this bias comes from and how to fix it.

People

Leah Saldich, Christy Wilcox, Sarah Crespi

Companies

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Books

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Content Warnings:

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Speaker A
This podcast is supported by the Icon School of Medicine at Mount Sinai, one of America's leading medical research schools. How will advances in artificial intelligence transform medical research and medical care? To find out, we invite you to read a special supplement to science magazine prepared by Icon Mount Sinai in partnership with Science. Just visit our website@science.org, and search for frontiers of medical research Artificial Intelligence on May 1 and May 2, Icon Mount Sinai and the New York Academy of Sciences will be convening a major symposium in New York City on the new wave of AI in healthcare. For more information and to register, please visit events dot nyas.org aihealth. That's events dot nyas.org aihealth. The Icon School of Medicine at Mount Sinai we find a way this week's episode is brought to you in part by the Nomis and Science Young Explorer Award. Are you doing excellent research that deserves recognition? The NomIs and Science Young Explorer Award recognizes bold young researchers who ask fundamental questions at the intersection of the life and social sciences, researchers who take risks to address relevant and exciting questions with creative approaches, regardless of the research outcome. Submissions are due May 15. Visit science.org nomis. That's Nomis to apply today.

Sarah Crespi
This is the science podcast for May 3, 2024. I'm Sarah Crespi.

Speaker A
First up on the show, a roundup.

Sarah Crespi
With newsletter editor Christy Wilcox. We talk about the oldest ice ever found, how to combat mosquitoes with our own microbes, and about how recent research into conservation efforts shows that, broadly, they seem to be working.

Next, we're evaluating seismic hazard maps. Leah Saldich and colleagues used modern prediction maps on past quakes and found a mismatch. We talk about where this bias comes from and how to fix it.

Now we have newsletter editor Christy Wilcox. We're going to talk about some recent stories from the newsletter science advisor.

Christy Wilcox
Hi Christy.

Sarah Crespi
Welcome back to the podcast.

Christy Wilcox
Hi Sarah. Great to be here.

Sarah Crespi
So we're going to first talk about your pick, the one that you said, oh, I can talk your ear off about this one.

Christy Wilcox
So this is something that is really cool because you had an inkling about it in an earlier, earlier newsletter, and.

Sarah Crespi
Now you get to follow up and it's on mosquitoes, which is maybe something people are starting to think about this time of year.

Speaker D
I certainly am starting to think about it as the weather gets a little nicer and you start to want to go outside.

Christy Wilcox
Yeah.

Sarah Crespi
And so this is about how we can use our own microbes to fight off these bitey guys.

Christy Wilcox
Yeah.

Speaker D
So last year I wrote about a study where they were looking at. They call them volatile chemicals, the stuff that comes off of your skin, essentially your smell. But not all of these have a distinct smell to people.

Sarah Crespi
It's not all us, right? We're not creating all these odors?

Speaker D
No, no.

That's what's interesting is, so what they were looking at is they were looking at the different chemicals coming off of skin that are made by microbes on our skin. And they wanted to know if. If some of these were either repellent or attractant to mosquitoes that are looking for a place to land and feed. And so they found that there were several chemicals that, you know, either repelled or attracted mosquitoes. But there was one in particular, a version of lactic acid that seemed to have a pretty potent effect in terms of. Of helping mosquitoes find their spot that they can bite and feed and drink from.

Sarah Crespi
This wasn't on everybody. This was just on some people.

Speaker D
Well, the amount of it on different people varied based on their skin microbiome. And so that the idea is that this is produced by certain bacteria that naturally live on our skin. Some people have more of these bacteria than others, or versions of these bacteria that produce more of it than others.

Sarah Crespi
Some people do smell better to mosquitoes out there.

Christy Wilcox
They do.

Speaker D
They really do. It is absolutely a thing that some people are mosquito magnets and some people aren't.

So what they were sort of said in this earlier paper is that, hypothetically, this means that you could manipulate the microbes on a person's skin and make them more or less attractive to mosquitoes.

Sarah Crespi
So, bring us to today, which is the cool part.

Speaker D
So then what they did is they took a couple of bacteria that naturally live on skin, and they engineered them. They deleted an enzyme involved in producing this chemical.

These engineered microbes produce much, much less of it.

Christy Wilcox
And then they tested whether or not.

Speaker D
Mice with the engineered versions of these microbes were more or less attractive to mosquitoes than mice with the regular versions. And lo and behold, getting rid of this enzyme, getting rid of this compound, essentially made it so the mice were less attractive to mosquitoes. It worked.

Sarah Crespi
And the bacteria were okay, even though they weren't producing that special chemical anymore.

Speaker D
Yeah, yeah. This version of lactic acid or whatever, it didn't seem to harm them in any noticeable way. And they were able to colonize the skin and do fine. And they actually made these mice less attractive to mosquitoes for two weeks.

Christy Wilcox
Wow. Yeah.

Speaker D
I mean, this was not just a temporary effect. If you think about mosquito repellents. I mean, I'm out there spraying deet on me every few hours. Right. So.

Sarah Crespi
Right.

Speaker D
This is a potentially long lasting, and they called it a living mosquito repellent, which I thought was just the coolest.

Sarah Crespi
Now I'm starting to fantasize about microbes that we can smear on our skin.

Christy Wilcox
That protects us from the sun, that.

Sarah Crespi
Protects us from mosquitoes. Oh, it's so cool. Maybe that's a little far away, though.

Speaker D
Yeah. Yeah.

Christy Wilcox
I mean, possibilities are endless, I would say. All right.

Sarah Crespi
Okay, so we're only doing that one animal story today, and it wasn't even.

Christy Wilcox
A cute animal story. Sorry.

But we have an extreme story. So, this is the oldest ice ever dug up, and what we can learn.

Sarah Crespi
From something that is just so, so old.

Christy Wilcox
How old, trusty? How old?

Speaker D
6 million years. I was surprised by that number.

Christy Wilcox
I didn't know you could have ice.

Speaker D
That was 6 million years old.

Christy Wilcox
That blew my mind. Yeah.

Sarah Crespi
So where was it, then?

Speaker D
So, it was in Antarctica, but it was not in the usual place that they get antarctic cores. So the idea is they normally, when they drill for ice in Antarctica, they're sort of going in the interior of the island.

Christy Wilcox
That's where they have their campsites.

Sarah Crespi
That's where they're doing their work.

Christy Wilcox
Right. Yeah.

Speaker D
And they've got these, you know, big glaciers or whatever. They drill down, get a big, long core. But in this case, they got what they called blue ice, and it was actually from the coast.

And so this blue ice from the coast is older, but it's less of a.

Christy Wilcox
A clear record.

Speaker D
So you're not getting that nice, straightforward core where you can say, this one is this old, this one is this old, this one is this old.

Christy Wilcox
So they had to sort of figure.

Speaker D
Out how to date these properly, and they're a little bit harder to date, and they're a little bit harder to. To do all that with.

Christy Wilcox
But the payoff is that they're more.

Speaker D
Than twice as old as the ones that they had been getting.

Speaker E
What can we learn from looking so.

Sarah Crespi
Far back with ice? Like, what's captured in this ice record.

Christy Wilcox
That, you know, we haven't been able to see before? Are we looking at isotopes or what's in there?

Speaker D
So what they have is they have.

Christy Wilcox
Actually trapped bits of air, so little.

Speaker D
Bubbles of air that is trapped in this ice. And they can measure things like the CO2 in that air, so the carbon dioxide that is in that air. And one of the things that they found, for instance, is that when you had this giant temperature drop, right, when you had the ice ages coming on, and the world got really cold.

You didn't have a huge drop in carbon dioxide. And what they said is that that meant that carbon dioxide is really powerful, right? The fact that it didn't take much.

Christy Wilcox
Of a drop for that temperature to.

Speaker D
Change and that cooling effect to occur. So they're able to extract all of this amazing information from these bubbles of air and such that is trapped in the ice.

Sarah Crespi
Is this probably the oldest ice we're.

Christy Wilcox
Going to get, or is there older.

Sarah Crespi
Ice out there somewhere?

Christy Wilcox
So, I don't know if they can.

Speaker D
Get much more ancient than 6 million.

Christy Wilcox
Years in terms of this ice, but.

Speaker D
I know that they only got really small samples this time around, so they're hoping, they're going back and they're hoping to get, like, really big samples so that they can do more work with it.

Christy Wilcox
So one more story, and then I'm going to have to let you go.

Sarah Crespi
This was actually from a science paper.

Christy Wilcox
That was published last week on wildlife conservation, and they basically asked a really big question.

Sarah Crespi
Are these small efforts that are kind of going on all over the globe, people saving different populations or different ecosystems.

Christy Wilcox
In a piecemeal fashion?

Are they working to stop or even reverse a decline in biodiversity? Are they worth it? So, Christy, what's the answer? Yes. Yes, I'd love it.

Speaker D
I'm leaving it there. Turning my mic off.

Christy Wilcox
Okay.

Speaker D
No, what was really cool about this study is, I mean, we've had lots of studies that look at individual projects and try to figure out if this project is working. And what this study did was really take all of those studies and say, on the whole, if we look at these projects, are we more often than not succeeding? And when they looked at these projects, they didn't just say, like, oh, did biodiversity increase or did the conservation work? What they had to show is that it improved over what would have happened or some sort of control. So general increases in biodiversity or increases in plant cover that happened everywhere, not just where this special effort was being made didn't count. So, like, you didn't get credit for just a general increase. It had to have that control in there. And so that's what makes it really powerful and really accurate.

Christy Wilcox
I'm super excited.

Sarah Crespi
Positive news about the world is always good. Is the recommendation then to keep doing.

Christy Wilcox
It the way we're doing or do it harder?

Sarah Crespi
Like what?

Christy Wilcox
What does it mean? Like, just keep doing what we're doing?

Speaker D
I think it means that these efforts, even if they seem like they're expensive or they seem like they're hard to arrange or they're hard to negotiate.

Christy Wilcox
They're worth it.

Speaker D
They are. It is absolutely worth it. And we need to keep trying, basically. And don't give up is the message that I got.

Christy Wilcox
That's a good message. All right, Christy, what else would people be interested in reading from the newsletter?

Speaker D
Just this week we've had some really interesting ones. I mean, there was one about how an AI transcription service shilling hallucinates, essentially. So they've shown with chat GPT that it'll make things up. It'll make up facts, right? Like, it'll just pull things out of the ether. Well, apparently a transcription version, a version that is supposed to be listening to your audio and then turning it into words is hearing things and not just things. Really often, a lot of the time they are inappropriate or like racist or terrible things.

Speaker E
Oh, wow.

Christy Wilcox
So you don't want that doing live.

Sarah Crespi
Transcription for you at your event?

Christy Wilcox
That sounds like, yeah, we are not.

Speaker D
Ready for live transcription, that is for sure. And then another one that I thought was really interesting from this week is that we often think of, like, bloodhounds or german shepherds as these, like, super, super sniffers. And so that's why we train them to do bomb sniffing and all of the, you know, tracking down cadavers or whatever. Turns out all dogs basically have the same sense of smell, at least physiologically. And so the only differences appear to be in the motivation or ability to be trained.

Christy Wilcox
Yeah, like, so you could be taking.

Sarah Crespi
Our poodles, our labradoodles out to the.

Christy Wilcox
Airport to have them be little curly.

Sarah Crespi
Bouncy balls of fun.

Christy Wilcox
And also bomb sniffers.

Speaker D
See, I'm voting for pugs. I want to see a bunch of little bomb sniffing pugs.

Sarah Crespi
They sound like they can smell really good.

Speaker D
Just little snorters, like, running around.

Christy Wilcox
All right, Christy, thanks so much for.

Sarah Crespi
Coming on the show. Always fun to have you, and I'm.

Christy Wilcox
Glad we got to squeeze a few animals there in the end.

Sarah Crespi
Christy Wilcox is the newsletter editor for science advisor.

Christy Wilcox
Thanks, Christy. Thank you, Sarah.

Sarah Crespi
Stay tuned for a chat with researcher Leah soldich about using modern seismic prediction methods on past quakes.

Speaker A
This week's episode is brought to you in part by the Nomis and Science Young Explorer Award. Are you doing excellent research that deserves recognition? The Nomis and Science Young Explorer award recognizes bold young researchers who ask fundamental questions at the intersection of the life and social sciences, researchers who take risks to address relevant and exciting questions with creative approaches, regardless of the research outcome. Submissions are due May 15. Visit science.org nomis that's Nomis. To apply today, this week's episode is brought to you in part by the Eppendorf and Science Prize for Neurobiology.

Are you or one of your colleagues doing great neuroscience? If so, then we encourage you to apply for the prestigious Eppendorf and Science Prize for Neurobiology, an international prize which honors young scientists for outstanding neurobiological research based on methods of molecular cellular systems or organismic biology.

Submissions are due June 15. Visit science.org eppendorf to apply today.

Speaker E
Seismic hazard assessments are used to set up building codes and to even plan earthquake damage mitigation strategies. But how good are these assessments that are used for such practical purposes? How good are they actually at predicting earthquake intensity? This week in science advances, Leah Saldich and colleagues looked at this odd disconnect between what the seismic hazard assessments say and what happens in the real world.

Sarah Crespi
Hi, Leah.

Speaker E
Welcome to Science Podcast.

Christy Wilcox
Hi.

Leah Saldich
Thank you so much for having me, Sarah.

Speaker D
Sure.

Speaker E
So what brought this disconnect or this idea that maybe these assessments that people are using for structures or for insurance that they might not actually match up with real world shaking intensity?

Leah Saldich
We have a saying in seismology that earthquakes don't kill people, buildings kill people.

And a crucial input to building design codes is seismic hazard maps that try to forecast how much shaking to expect with a certain probability over many years, given the lifetimes of buildings and other structures, so that engineers can design them appropriately. Hazard maps are also important for insurance and reinsurance rates and emergency management and mitigation. Like you said, seismologists and earthquake engineers have been making these maps for a long time, but it turns out they knew very little about how well they actually forecast shaking, given the short record of past earthquakes. Our team was very interested in figuring out how to evaluate the performance of these maps to see if they were actually accomplishing what they're supposed to do.

Speaker E
Why do you say that? The records are short.

Leah Saldich
Yeah. So a big obstacle to evaluating hazard map performance is what we call the short instrumental record of earthquakes, recording of earthquakes by seismometers, which can really accurately measure ground motions. And those seismometers were invented around 1900. But the human record of earthquakes and earthquake shaking goes back much further.

Humans have always been curious about earthquakes and have been keeping records of damage from earthquakes for a long time.

There's this measure of shaking that seismologists use, which is based directly on human perceptions of shaking and the damage caused to structures by shaking.

Speaker E
So we don't have a little needle that's like shaking on a piece of paper that's recording this event. We have a building fell down or this bridge collapsed.

Leah Saldich
Exactly.

Speaker E
Historians collected that information from whatever kind of public records have been taken down throughout much longer history. Oh, that's super interesting. Can you give an example of a record that would be in that data set? Do you have anything that comes to mind?

Leah Saldich
Me and my team worked on creating an intensity data set for the state of California. It goes back to 1857, when an earthquake happened called the Fort Tejon earthquake. We looked through lots of historical compilations of those shaking felt reports that were collected by the government at the time, the US coast and Geodetic Survey, which eventually became the US Geological Survey. And an example of some of the felt reports would be hanging pictures, swung on walls. That's a really low intensity. It might move up to windows rattled, and then things fell off shelves, up to heavy furniture being moved, and then finally to structural damage, cracks in the walls, corners falling off, all the way to homes slipping off their foundations.

Eventually, the top of the scale is complete destruction.

Speaker E
This reminds me that when there is an earthquake today, you can go onto. I can't remember what the website is and just enter your shake report.

Sarah Crespi
Right.

Speaker E
These are still collected even today?

Christy Wilcox
That's right.

Leah Saldich
Today we call it did you feel it is the program that's operated by the US Geological Survey. So if you felt an earthquake, you can go onto that website and there's a questionnaire which will ask you questions that are related to that intensity scale. So, to those observations that I was just listing before, if things swung on your wall, if things fell over on your tables, up to severe structural damage.

Speaker E
How can you translate. A building fell down, my hut fell down. Into a sensible record that we can use today to kind of estimate back in the past how strong an earthquake was.

Leah Saldich
We combine all of the historical reports and photographs of shaking and damage that we can find in a region to map out the distribution of ground motions. We combine these shaking footprints to create catalogs of maximum observed shaking in a region over time.

How we use that to compare directly to the hazard models and maps is through.

It has a funny name, but basically it's called ground motion intensity conversion equations. G mice. These are conversion equations that allow us to directly compare those historical shaking intensity data to the numerical methods that we use in hazard modeling.

Speaker E
Yeah, I guess I'm a little surprised that the modeling for the seismic hazard maps, it doesn't have any reference to this older stuff. It is only based on seismometer readings. Is that kind of what you're saying.

Leah Saldich
Here, these seismic hazard models are the end result of many other models. So we've got models of known fault locations, models of unknown fault locations, models of the frequency and magnitude of earthquakes on those faults, and then models of how ground shaking decays away from the epicenter of an earthquake. Those all combined result in this hazard model, which forecasts expected shaking with a given probability over a given time in one of the instrumental measures from a seismometer.

Speaker E
All of that to say that you can take the hazard maps that you've constructed from these models today and then look at past shaking incidents that were not measured with seismometers and say, how accurate your hazard map is. Is that kind of what you did here, exactly how did they line up with each other when you looked at the past? Were these seismic hazard models? Were they predicting what people would have felt in those times?

Leah Saldich
Wherever we looked around the world, from California to Italy to Nepal to Japan to France, the hazard map seemed to predict much higher shaking than the historic record shows.

It's important to note that even in a perfect world, we would not expect the forecasted maps to perfectly predict shaking as. As there is a component of randomness to earthquake occurrence. But around the world, seismic hazard maps always over predicted the observed shaking, which indicates that it is a very general phenomenon. So there has to be a very general explanation.

Speaker E
Japan and Nepal, they have these historic datasets as well.

Christy Wilcox
That's right.

Leah Saldich
And they go back even longer than the historical record. In California, in regions like that, we have records of the shaking data that go back over a thousand years of human history.

Christy Wilcox
Wow.

Speaker E
Since this discrepancy is all in one direction, you know, did you have some ideas about why there might be this overestimation of intensity from the modern seismic assessments?

Leah Saldich
There are a lot of things which affect the comparison in a subtle way, but we found that the biggest contributor to that result is the conversion of the historical shaking intensity data to the numerical methods that we use in modeling. So it was those conversion equations that allow us to compare the different kinds of measures of shaking.

Speaker E
Does that mean that those conversions are quote unquote incorrect? Like, what can you say? Like, can you say that they just. What does it mean that those conversion equations were incorrect?

Leah Saldich
We would say that the conversion equations give a biased result. So once we use those conversion equations, the output is biased high from the standpoint of mitigating earthquake risk. It's encouraging that much of the apparent overprediction of earthquake hazard results from these conversion equations, rather than a systematic effect in the earthquake hazard modeling approach.

Speaker E
Wait, can you say that again? I don't think I followed that.

Leah Saldich
We find it encouraging that much of the apparent overprediction of earthquake hazards with respect to the observation results from these conversion equations.

So rather than there being a systematic effect or problem in the way that we approach earthquake hazard modeling, it's just a small piece of the evaluation that is biasing the results in one direction every time.

Speaker E
So you're saying that the modern seismic modeling that they use for the hazard maps, that doesn't have this piece inside of it. So we're not making mistakes today, but like, when we go to evaluate our models based on past feeling reports, that is a problem that hasn't been working correctly.

Leah Saldich
That's correct.

Speaker E
So that is reassuring. And it's also reassuring that it's in one direction. So if we were depending on it, we would be overbuilding, not underbuilding.

Leah Saldich
Exactly.

Speaker E
What does this mean for the field? Does that suggest that needs to be a different way to make the comparisons that you wanted to do here?

Leah Saldich
Yes. So improvements to these conversion equations have been proposed by my colleagues and co authors on this paper, Molly Gallahue and Norman Abrahamson. Using these new unbiased conversion equations will improve the comparisons of hazard forecasts to observed shaking.

Speaker E
What would that do in the long run? Does that just mean you're going to have more confidence in predicting or understanding different regions of the world, their seismic activity?

Leah Saldich
Yes, exactly.

Speaker E
Thank you so much, Leah.

Leah Saldich
Thank you, Sarah.

Speaker E
Leah Saldich is a geoscience peril advisor at Dicarpenter. During the time of the research for this paper, she was a geoscientist in the USGS. You can find a link to the science Advances paper we discussed@science.org.

Sarah Crespi
Podcast and that concludes this edition of the Science podcast. If you have any comments or suggestions, write to us at sciencepodcast@aaas.org to find us on a podcasting app, search for Science magazine, or you can listen on our website, science.org podcast. This show was edited by me, Sarah Crespi, and Kevin McLean. We also had production help from Megan Tuck at Prodigy. Jeffrey Cook composed the music on behalf of science and its publisher, Aaa's. Thanks for joining us.