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Hi, Mexico.
How are you feeling after that significant shake? Looks like the Cocos plate dove a bit deeper under the North American plate today, continuing its 60 mm/yr journey into the depths. https://twitter.com/usgsbigquakes/status/1275455693902893057
How are you feeling after that significant shake? Looks like the Cocos plate dove a bit deeper under the North American plate today, continuing its 60 mm/yr journey into the depths. https://twitter.com/usgsbigquakes/status/1275455693902893057
Lots & lots of video I can’t verify but are neat for demonstrating concepts.
Beware I’m not going to be able to pluck the original posters nor establish beyond plausibility that they’re from today while we dive into the science.
Beware I’m not going to be able to pluck the original posters nor establish beyond plausibility that they’re from today while we dive into the science.
Guitar strings vibrate at particular frequency based on length & thickness.
So do buildings.
Tightly-packed mixed-height buildings can be dangerous during quakes as they all sway slightly differently & can actually smash into each other: https://twitter.com/oncenoticiastv/status/1275471821278601216
So do buildings.
Tightly-packed mixed-height buildings can be dangerous during quakes as they all sway slightly differently & can actually smash into each other: https://twitter.com/oncenoticiastv/status/1275471821278601216
Every water body has a resonance frequency where it produces waves that align perfectly to constructively interfere with themselves, building bigger & bigger.
Seismic waves often align up with swimming pool resonance.
Store display hot tub (?) seiche: https://twitter.com/jinxywera/status/1275464173938339841
Seismic waves often align up with swimming pool resonance.
Store display hot tub (?) seiche: https://twitter.com/jinxywera/status/1275464173938339841
You can watch the channel seiche slowly build in this clip, each rebounding wave adding to the next.
Note:
the pups are fine, but please don’t go frolicking in seiche. In more wild conditions (like a tsunami resonating within a bay) they hide vicious currents. https://twitter.com/roger13as/status/1275460403061878786
Note:
the pups are fine, but please don’t go frolicking in seiche. In more wild conditions (like a tsunami resonating within a bay) they hide vicious currents. https://twitter.com/roger13as/status/1275460403061878786
Seismic codes are being constantly revised and updated as structural engineers learn more about how to absorb energy without breaking.
A common tactic is to build in flexibility and gaps.
Which can be a tad bit unnerving: https://twitter.com/aztecanoticias/status/1275477676577288193
A common tactic is to build in flexibility and gaps.
Which can be a tad bit unnerving: https://twitter.com/aztecanoticias/status/1275477676577288193
Sidewalks and roads can also break without built-in flexibility. So... gaps!
Note:
During an earthquake, please drop! (or lock! mobility devices) cover! & hold on! Walking on literally unstable ground is not a great idea. https://twitter.com/borderlineason/status/1275458572046856192
Note:
During an earthquake, please drop! (or lock! mobility devices) cover! & hold on! Walking on literally unstable ground is not a great idea. https://twitter.com/borderlineason/status/1275458572046856192
I’m seeing very few building damage vides (yay!), so I’m hesitant that this is from today. Even if it’s not, it’s a REALLY GOOD example.
Entering/exiting buildings is dangerous because that’s where shit is falling. Eek!
Stay inside OR outside until shaking stops. No fleeing! https://twitter.com/elpunto_mex/status/1275480497817137152
Entering/exiting buildings is dangerous because that’s where shit is falling. Eek!
Stay inside OR outside until shaking stops. No fleeing! https://twitter.com/elpunto_mex/status/1275480497817137152
Ideally, in a good building, your primary worry isn’t the building, but things inside the building.
Kitchens are by far my least-preferred place to be at home during quakes. Note the plate shards: https://twitter.com/ibero909fm/status/1275479861352493056
Kitchens are by far my least-preferred place to be at home during quakes. Note the plate shards: https://twitter.com/ibero909fm/status/1275479861352493056
Buildings of different heights swaying at different frequencies, but up close & personal: https://twitter.com/bon_miller/status/1275480792915828736
Structural engineering for earthquakes isn’t just about absorbing energy. That flexibility needs to be balanced against enough rigidity for buildings to hold their shape.
...as rather terrifyingly demonstrated by this untied rebar that doesn’t yet have cross-bracing. (Ahhhhh!) https://twitter.com/bersa76/status/1275489246275670017
...as rather terrifyingly demonstrated by this untied rebar that doesn’t yet have cross-bracing. (Ahhhhh!) https://twitter.com/bersa76/status/1275489246275670017
Oh, wow. This lamp fixture is kinda perfect as a seismics demo.
Notice all the identical mini-pendants swing at the same frequency, but the rigid shell stats steady? https://twitter.com/gothaminformer5/status/1275454014675488769
Notice all the identical mini-pendants swing at the same frequency, but the rigid shell stats steady? https://twitter.com/gothaminformer5/status/1275454014675488769
Perfect angle on this swimming pool seiche!
It’s a single standing wave across. The crest & trough align so that it’s like the water is bouncing up and down.
ProTip: bathtubs resonate at a tens of seconds if you swish back& forth. https://twitter.com/caromeug/status/1275458890868506624
It’s a single standing wave across. The crest & trough align so that it’s like the water is bouncing up and down.
ProTip: bathtubs resonate at a tens of seconds if you swish back& forth. https://twitter.com/caromeug/status/1275458890868506624
Because swimming pool seiche are all about seismic waves matching the resonance frequency of the pool, they amplify to the point where you can still get them so far from the epicentre that you barely even notice ground shaking.
Like this: https://twitter.com/hayes_ernest/status/1275465398045949953
Like this: https://twitter.com/hayes_ernest/status/1275465398045949953
When waves propagate, the individual particules within the medium barely move. Energy propagates, matter not so much.
For example, while the wave splashes out, the bananas only bob back & forth in this unexpected fluid dynamics demo: https://twitter.com/desdepeninsula/status/1275489952898441216
For example, while the wave splashes out, the bananas only bob back & forth in this unexpected fluid dynamics demo: https://twitter.com/desdepeninsula/status/1275489952898441216
Look, I really, really love swimming pool seiche. I find their regularity weirdly soothing.
Slosh, slosh, slosh... https://twitter.com/scgbts/status/1275461610568441856
Slosh, slosh, slosh... https://twitter.com/scgbts/status/1275461610568441856
Seiche can happen with any multiple of the seismic frequency. Instead of one standing wave, this pool has a whole series of them.
...sigh. The dramatic length vs width dimensional difference on this pool make me wish I know its orientation vs seismic wave propagation direction. https://twitter.com/carloszup/status/1275494162373238786
...sigh. The dramatic length vs width dimensional difference on this pool make me wish I know its orientation vs seismic wave propagation direction. https://twitter.com/carloszup/status/1275494162373238786
The pool covers & lane dividers are another neat demo on how material properties impact structural behaviour during oscillation.
A tarp is a solid yet flexible object. It stays the same dimensions, but moves with the disruption without breaking. https://twitter.com/ponchole/status/1275463127597854720
A tarp is a solid yet flexible object. It stays the same dimensions, but moves with the disruption without breaking. https://twitter.com/ponchole/status/1275463127597854720
Seiche are significantly less soothing in industrial settings. https://twitter.com/theking12k/status/1275494549855625223
