Cara Giovanetti

References
link.springer.com/chapter/10.1...
www.edp-open.org/images/stori...
escweb.wr.usgs.gov/share/mooney...

Further reading:
You can read a firsthand account of the 1887 earthquake here: archive.org/details/sim_...
It’s beautiful and I wish scientists still wrote like this.

A (paywalled :/ ) account of what happened in the mines during this earthquake is at pubs.geoscienceworld.org/ssa/bssa/art...

The 'Banqueting Hall' beneath the site of Joseph Williamson's house, Mason Street, Liverpool, lit with worklights to look like an underground dining chamber. Hopefully not the future of life in earthquake-prone California... By Kyle J May - Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=79905452

So for those of us far enough from the Hayward fault—maybe the future of earthquake-proofing is subterranean?

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Deep underground, only the coherent P- and S-wave parts of the earthquake are felt, which is why mines tend to make it through earthquakes unscathed if they’re not near the fault line. The miner in the episode above was in an area of softer rock, further damping the shakes other miners felt.

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P and S waves as before, but now also showing surface waves (Rayleigh and Love waves), which are more destructive than the P and S waves. By LukeTriton, Steven Earle, Mario Bačić, Lovorka Librić, Danijela Jurić Kaćunić, Meho Saša Kovačević - Modified after:Bačić, Mario et al. “The Usefulness of Seismic Surveys for Geotechnical Engineering in Karst: Some Practical Examples.” (2020). Distributed under CC by 4.0 here https://www.mdpi.com/2076-3263/10/10/406Earle, S. (2015). Physical Geology. Victoria, B.C.: BCcampus. Distributed under CC by 4.0 here https://opentextbc.ca/geology/chapter/11-3-measuring-earthquakes/, itself being based on https://commons.wikimedia.org/wiki/File:Rayleigh_wave.jpg and https://commons.wikimedia.org/wiki/File:Love_wave.jpg, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=133937782

But when the wave reaches the surface, two new kinds of waves join the mix. This is because the propagating wave hits a boundary—the edge of the material it was moving through—and new, violent motions can result.

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P-wave (compression and stretching along direction of wave) and S-wave (movement up and down perpendicular to direction of wave). Image via USGS https://www.usgs.gov/media/images/p-waves-and-s-waves-crust, public domain

Earthquakes produce different kinds of disturbances in the earth’s crust. As the quake propagates out from the epicenter, it largely sources two kinds of disruptions: “P-wave” (like compressing and stretching a slinky), and “S-wave” (like shaking a rope up and down).

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Damage to the Newhall Pass Interchange, following the 1971 San Fernando earthquake in Southern California. Image via PICRYL, public domain.

It’s not the only record of differing earthquake experiences above and below ground. In Los Angeles in 1971, miners had no trouble operating their trolleys to investigate the electrical issues caused by an earthquake. But above ground, trains were inoperable because of track damage.

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A dilapidated building in the wake of the 1887 Sonora earthquake. Photo date 1887, obtained via Arizona Geological Survey (https://azgs.arizona.edu/1877-earthquake-san-bernardino-valley-sonora).

In May 1887, southern Arizona was rocked by an earthquake so strong that columns of water erupted from wells and fires ignited mountain ridges.

But nearby, a miner dismissed his colleagues’ warnings about shaking as a joke—and was found undisturbed after the event.

What happened?

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A photo of coronas glowing on the tips of tree leaves.

A photo of coronas glowing on the tips of tree leaves.

A new study published earlier this month in Geophysical Research Letters reveals how the tips of tree leaves burn with ghostly, ultraviolet sparks. These phenomena, known as coronas, had never been seen in nature—until now. 🌿 spklr.io/6042DI2EC

📸: William Brune

Sunflower! It's what wikimedia commons had for me haha

References

nph.onlinelibrary.wiley.com/doi/10.1111/...
www.sciencedirect.com/science/arti...
www.journals.uchicago.edu/doi/10.1086/...
onlinelibrary.wiley.com/doi/abs/10.1...

Dew drops speckling a blade of grass. They gather there because the vapor pressure deficit is very small! Image credit Balaram Mahalder - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=11207327

Vapor pressure deficits tend to be smaller at night, when the air is cool. It’s why dew forms early in the morning—the air is so saturated that water collects on plants and other surfaces. Trees “know” this, and so they force water into their cells to grow when these deficits are smallest!

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The vapor pressure deficit is the difference between the maximum amount of moisture the surrounding air can hold, and the actual amount of moisture in the air. If the surrounding air is dry, there’s a big risk of losing water. But if the air is moist, evaporation is harder.

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Percentage of growth in the space of vapor pressure deficit (VPD) and soil water potential (SWP). The most growth occurs at the left of the graph, where vapor pressure deficit is smallest. Reproduced from Zweifel et al 2021, "Why trees grow at night", New Phytologist, https://nph.onlinelibrary.wiley.com/doi/10.1111/nph.17552, CC BY 4.0

Trees need tons of water to do this. But there’s risk of water evaporating from parts of the tree above the soil if too much water is drawn up.

So trees avoid this risk by growing in the middle of the night, when the so-called “vapor pressure deficit” (VPD) in the surrounding air is small.

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A diagram showing what happens inside a cell when different amounts of water are drawn into it. In the last image, the cell is "turgid" and the water pressure is high--a plant cell can begin to elongate under these conditions. Image credit LadyofHats via wikimedia commons, Public Domain, https://commons.wikimedia.org/w/index.php?curid=1685428

But plant cell walls are pretty inflexible—to expand them, plants need to create enormous internal pressures in cells to push cell walls outward. They do this by drawing large amounts of water into their cells, creating pressures up to 5 times as high as the air pressure in your car tires.

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Cross section of a young buttercup under a microscope. Toward the bottom of the image, there are large cells responsible for the transport of water and mineral ions throughout the plant, surrounded by smaller structural support cells for these channels. Between the outer edge of the plant and the large transport cells are cells whose main function is supporting the stem. They vary in size, but some of them are quite large! Image by John Bebbington FRPS via Flickr, CC BY-NC-SA 2.0 https://creativecommons.org/licenses/by-nc-sa/2.0/deed.en

Part of the growth of trees involves the growth of individual cells. Cells become permanently elongated in processes faster and more energy-efficient than cell division alone. This helps plants reach sunlight quickly in early life.

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Trees, like kids, mostly grow at night. But while growth cycles of children have more to do with biology, trees grow at night because of physics.

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a mostly empty microsoft word document with text partway down the page that reads "think trees arboring? think again"

how drafting this weekend's explainer is going

Maths and biology conspired to make something beautiful: the world’s largest floating leaf (genus Victoria), spanning up to 3 m across. We decoded this enigma with mathematical modelling to show the lattice is an economy of material– the most structurally efficient way to cover a large surface area.

this guy in particular has been relentless. NO I DO NOT WANT TO PAY YOU $2000 TO MAKE AN ANIMATED VIDEO OF MY OPINION PIECE

could you imagine if I was like "yes I will organize a conference on cell science and molecular biology"

Simple rules for construction of a geometric nest structure by pufferfish - Scientific Reports Scientific Reports - Simple rules for construction of a geometric nest structure by pufferfish

This thread is based on work from Mizuuchi et al 2018, “Simple rules for construction of a geometric nest structure by pufferfish”, Scientific Reports volume 8, Article number: 12366, www.nature.com/articles/s41... Springer Nature Open Access/CC-BY 4.0

All videos reproduced from this article

YouTube video by Nature on PBS Pufferfish Builds Sand Sculpture for Mating

So simple, stochastic geometrical rules can lead to these stunning patterns on the sea floor! As a fun bonus, PBS used a robotic pufferfish to spy on real pufferfish to see what they do once they’ve built these nests. Happy Valentine's Day!

www.youtube.com/watch?v=1k0M...

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The authors of this 2018 study showed with computer simulations that these simple rules are enough to make patterns that look like the pufferfish nests! This is super impressive to me, since you can see the initial excavation angles don’t always point directly inwards but converge over time.

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Then it follows a simple set of rules:
1. Always excavate the outer ring from the outside in
2. Excavate in short, straight lines
3. After a short initial stage, only excavate low-lying areas in the outer ring

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Initial footprint of a white spotted pufferfish nest; the center region has been excavated, but the outer rings have not been formed yet, and the maze-like pattern in the center has yet to appear. Image credit Kawase et al 2017, "Discovery of an Earliest-Stage “Mystery Circle” and Development of the Structure Constructed by Pufferfish, Torquigener albomaculosus (Pisces: Tetraodontidae)", Fishes 2017, 2(3), 14; https://doi.org/10.3390/fishes2030014, CC-BY 4.0

The trick? Keeping it simple. A team of researchers in 2018 showed that pufferfish make these nests by repeating very simple actions, hundreds or even thousands of times. First, the pufferfish will excavate the circular region in the center with their fins and body.

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Freshwater fish building nests that do not seem nearly as regular as the white spotted pufferfish's nest; they're irregular in shape and are mostly pits in the sand. Image credit snowmentality via Flickr, CC BY 2.0.

To boot, their nests have been described in the literature as “much more geometrically ordered than any known nests built by other fish.” How do they manage this feat of engineering?

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These rings are made by male white-spotted pufferfish, looking to attract a mate. That should surprise you, because the pufferfish are only about 4 inches long, and yet these rings have diameters of over 6 feet!

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A strange-looking ring-like pattern in the sand, with a flat circular space in the center. A camera is set up in the top left. Image credit Kawase et al 2022, "3D model of the geometric nest structure, the “mystery circle,” constructed by pufferfish", Scientific Data volume 9, Article number: 368 (2022) . Springer Nature Open Access/CC-BY 4.0

Divers began to notice strange, crop-circle-like rings on ocean floors in Japan in the late 1990s. Their origin puzzled scientists for years!!

But these rings aren’t made by aliens, supernatural currents, or human activity—they’re actually an expression of love <3

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In an effort to preserve and prioritize my attention I virtually always block people who are rude to me but I also sometimes block people who are perfectly polite and could very well be lovely individuals because I absolutely cannot be trusted not to waste precious hours of my life debating them 🫠