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Comment by baq | Hacker News Reader

shakemap: https://earthquake.usgs.gov/earthquakes/eventpage/us7000pn9s...

Mandalay looks to be almost exactly in the center of the worst of it...

That straight line in the map doesn't look like the maps for any earthquakes I've felt. It looks like it was on the Sagaing Fault which is a different type of fault from the ones I've experienced.

https://en.wikipedia.org/wiki/Sagaing_Fault

2023 Turkey-Syria Earthquake has a ShakeMap similar to this event [1]; We often think of the epicenter as a single point in earth where the energy then radiates outward. In reality, a fault is more similar to line [2]. The energy radiates outward around the entire fault line.

(Note: since earthquake magnitude is correlated with the amount of area moved, it is safe to assume that larger earthquake will have larger fault rupture)

[1] https://en.wikipedia.org/wiki/2023_Turkey%E2%80%93Syria_eart... [2] https://earth-planets-space.springeropen.com/articles/10.118...

Interesting, the idea that a fault is a more of a line source makes sense it is hard for me to think of a way to have a single point source slip with enough energy. I guess I've thought in subduction faults the depth of the slip might explain why there is a point source. For example in the Pacific Northwest the earthquake from the Juan de Fuca plate look to be substantially deeper than this one. (50km vs 10km) Of course I expect the depth from today to be preliminary and be adjusted later, I can see the extent of red region in the shakemap changed to be longer from when I looked at it an hour or two ago.

Do you know if the line source model comes from having more and better seismographs or has there been a change in how people think about the motion of a fault in an earthquake?

quoting from the 'Hazard' section:

> The length of fault running 260 km (160 mi) from 19.2°N to 21.5°N, on the Meiktila segment, is designated a seismic gap due to the absence of major earthquake ruptures since at least 1897. At least 2 m (6 ft 7 in) of slip has accumulated along the fault corresponding to a magnitude 7.9 earthquake.

Science did pretty well here with the magnitude. Wonder how much more research is needed to be able to predict an event let's say a full minute before it happens...

and PAGER: https://earthquake.usgs.gov/earthquakes/eventpage/us7000pn9s...

> Estimated economic losses are 6-70% GDP of Burma.

6-70% holy crap what a range.

Probably meant 60-70%

It's worth noting that the scale of the graph above it has a _logrithmic_ scale so I do think it is actually 6% to 70%.

That page is estimating fatalities of 10k to 100k people and economic losses of 10B to 100B USD.

(For context: Myanmar GDP is about 67B USD, according to Wolfram Alpha.)

I think they are making that prediction from nothing more than their seismographs, the population density and GDP at the affected locations.

If so, it isn’t surprising there’s a lot of uncertainty in their estimates.

Also look at the histogram with of “Estimated Fatalities”. The highlighted bar is for “10,000 to 100,000”

60-70% loss in GDP would mean the literal end of the country, it's a ludicrously large figure no one could ever rebuild from. This is a 7.7 earthquake; it probably is 6–7% GBP which is still significant.

It’s only $40B, Myanmar is exceptionally poor. For example, AAPL’s net profit is higher than Myanmar’s GDP.

I’m pretty sure China can dig around in their couch cushions and help them out, the military junta is heavily reliant on China already.

Probably the ‘shadow GDP’ of Myanmar from heroin and scam call centers is higher than the official GDP, but that’s pure speculation on my part.

Not Myarmar, but in Cambodia scams are soon or already larger business than official GDP

https://thediplomat.com/2024/09/laos-and-cambodia-dont-inclu...

it is possbile , we are at literal end of the country with Junta bombing whatever they want and Revolution forces fighting to save the country .

60% loss can be recouped by 10 years of compounding 5% growth.

Mathematically valid, but...

If Myanmar had a stable and reliably growing economy, the world would be a different place.

Turning Myanmar into a country with a stable economy that could grow at 5% annually would be worthy of a Nobel Prize in economics.

Practically, recovery costs in the neighborhood of 60% of Myanmar's GDP represents many decades of development. Or enormous foreign aid from China. I'm not sure how valuable Myanmar is to China though.

We almost had that chance back in 2010-2020.. only if coup and COVID didn't happened..

That's assuming otherwise zero growth, or other nations standing still or stuff like that.

Also, 10 years of constant 5% growth is a lot to ask for in general. Maybe not impossible, but really hard. Now, think that you need to have 5% growth in the first year after the earthquake, in a devastated nation. Infrastructure destroyed, people killed. Lots.

It sounds pretty near to impossible.

These numbers have some meaning you know. It's easy to type "5% growth". Much, much harder to actually achieve it.

How is the dead part of the population being replaced in this scenario? Who is achieving this growth if the population is decimated?

I'm not sure about any of these questions, I am just pointing out how wrong it is to suggest that a -60% economic setback is historically fatal. The economy of Myanmar increased 8-fold in the last 30 years.

60% loss in GDP is roughly 60% loss in population. You don't recoup citizens in 10 years with 5% growth.

You're suggesting this earthquake killed thirty million people?

No i'm suggesting that the earthquake didn't kill that many people, so it cannot have lost 60% GDP which makes no sense whatsoever.

I hope not... I'd rather this was indeed 6-70 with a mode much closer to 6 than 70

It also appears to have gone through the heart of Tatmadaw territory [1].

[1] https://en.m.wikipedia.org/wiki/Myanmar_civil_war_(2021%E2%8...

Yeah several Junta building destroyed including notorious tataroo military Air field which is responsible for bombing several hundred of innocent civilian's.

How is the state of the various other bridges beside Saigang (eg. Chauk, Pakokku, Magway, Pyay, Tigyaing)?

Much of Saigang, Rakhine, and Kachin might be cut off from the rest of Myanmar, dramatically affecting logistics (though I think land logistics to Rakhine have already largely ended before the earthquake)

Also, I hope your family hasn't been drastically impacted.

Thanks a lot! My family is fine in Yangon. Yangon didn't got hit much. Bangkok got hit harder. Several bridges collasped in Sagaing and Mandalay.

> Thanks a lot! My family is fine in Yangon. Yangon didn't got hit much

Glad to hear! That is a massive silver lining!

That shakemap looks really suspicious, relative to the damage being reported in Thailand, especially Bangkok. 600 miles away (~1000 km) and the shakemap's reporting numbers like 3 to 4 on the intensity scale. When they reported the skyscraper collapsing in Thailand, at first I thought it was Chiang Mai near the border of Myanmar, not Bangkok 600 miles away. For Americans, that's like the big one hits the Cali fault, and skyscrapers are falling down in Salt Lake City or Phoenix.

Wonder whether that's just automated simulation output, rather than actual measurements from stations? Numbers 3 and 4:

3 - Felt noticeably indoors, especially in tops of buildings, yet many do not even notice there's an earthquake.

4 - Felt indoors by many, felt outside by few. Sensation like heavy truck striking a building.

Bangkok's reporting sensations, crowd behavior, and events more like a 6 to 7. Everybody runs, furniture moves, plaster falls, considerable damage to poorly built (partially finished) structures. A 3-4 is like, you barely notice, or think a really heavy vehicle just crashed or something. Not, everybody in town runs in panic, describes all the ceilings collapsing, cracks in walls afterward. [1][2][3][4]

Expect there's probably going to be some re-evaluation of the magnitude and scale of the earthquake based on what was actually reported by observers, cameras, and damage afterward. They're reporting slight damage and cracks even in relatively well constructed buildings.

Edit: This story from ChannelNewsAsia in Singapore has camera footage from somebody on the ground near the skyscraper collapse. Visibly shaking the camera holder. [5]

[1] Intensity, Text Descriptions: https://sciencefest.indiana.edu/wp-content/uploads/2020/10/m...

[2] Semi-common Cone Chart with Energy Comparison: https://basecampconnect.com/wp-content/uploads/2022/01/eartq...

[3] Japanese Chart with Pictures: https://miro.medium.com/v2/resize:fit:1400/1*Ca_yV0l_zkWiFtg...

[4] Another Picture Chart: https://d9-wret.s3.us-west-2.amazonaws.com/assets/palladium/...

[5] ChannelNewsAsia, https://www.channelnewsasia.com/asia/massive-quake-kills-nea...

Bangkok is built on a muddy floodplain. The soft ground accentuates the ground motion by the jello-wobble resonance effect. High-rise buildings that do not have seismic isolation or counter-weight damping (like Taipei 101) will suffer dramatic whiplash shaking at the top.

https://www.atlasobscura.com/places/tuned-mass-damper-of-tai...

Some cities closer to the epicenter, such as Chiang Mai, are also on floodplains, but have many fewer high-rise buildings. Some smaller condo blocks there have been deemed unsafe after the earthquake.

https://www.chiangmaicitylife.com/citynews/general/following...

USGS Shakemap intensity is based on the peak ground acceleration (PGA). It has been known that, in some cases, PGA does not correlates well with structural damages. The peak ground velocity (PGV) has better correlation with structural damages [1].

Even so, they are only describing the peak values, it does not describe the ground motion frequency or other ground motion characteristic [4]. It is hard to compress a complex phenomenon into single value.

My colleagues suspect that the soil condition in Bangkok (soft soil and basin) and the distance from the epicenter amplifies long period/low frequency content of earthquake waves, making skycraper to be more vulnerable to damages. Example of basin effect is 1985 Mexico City Earthquake [2] and example of long period effect is the 2011 Tohoku EQ [3]

(Note: Magnitude value would probably be stable, they are based on the energy released by the earth (Moment Magnitude), Intensity is just the on-the-ground observation of the earthquake and it can be subjective.) [1] https://www.cwa.gov.tw/Data/service/hottopic/20191213_SC_New... ; https://www.ncdr.nat.gov.tw/CEOCworkshop/cwb_2.pdf [2] https://en.wikipedia.org/wiki/1985_Mexico_City_earthquake [3] https://en.wikipedia.org/wiki/Long_period_ground_motion [4] https://www.iitk.ac.in/nicee/wcee/article/WCEE2012_5499.pdf

The geometry of the fault may have something to do with it, maybe some constructive interference at play...?

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