Japan Issues First Ever Mega Earthquake Warning

[maxglute]

From wiki of potential 100-150 year Nankai megathrust earthquakes event (JP predictions 70%-80% chance within next 30 years)

>The Japanese government estimates that a major earthquake on the Nankai Trough would cause 169.5 trillion yen in direct damage and 50.8 trillion yen in economic losses for the following year. A study by the Japan Society of Civil Engineers in 2018 estimated that the long-term damage from the earthquake could result in 1,240 trillion yen in economic losses over a 20-year period.[11] It is predicted that the economic damage is likely to be 10 times higher than for the 2011 Tōhoku earthquake and tsunami.[12] A death toll as high as 230,000 has been suggested for such an event.[13]

Early warning / evacuation can reduce casualty by 80%+. 1240T yen = 8.5T USD. 1.5T direct+next year loss = 40% of GDP, with another 160% over next 19 years. Stupendous numbers.

[ano-ther]

Scary. It’s an alert though, not a warning yet

>Information from the agency on Nankai Trough megaquakes is delivered at two levels — an alert and a higher warning. The weather agency issued the lower level alert on Thursday, urging people to be prepared for cases requiring evacuation. No evacuations are required for the alert level.

> A warning means people would need to be on higher alert, and officials would urge those who wouldn’t be able to evacuate quickly to do so before any large quake occurs.

https://www.japantimes.co.jp/news/2024/08/08/japan/nankai-ea...

[endominus]

For reference; the earthquake that caused the massive tsunami and Fukushima nuclear reactor disaster 13 years ago was magnitude 9.0. This earthquake was 7.1, roughly 100 times less energetic, though the article notes that seismologists in Japan are warning that stronger earthquakes than this one are more likely than usual in the near future.

[teleforce]

This year this particular earthquake is the second time major earthquakes (magnitude higher than 7 Mw) occured in Japan. Globally it's the 4th major earthquakes including the ones in China and Taiwan. It's the highest earthquakes occurance frequency in recorded history.

[eigenform]

Kind of unsettling because there isn't obvious coupling between Hyuga-nada quakes and the Nankai megathrust in the historical record. See the leftmost column:

https://www.data.jma.go.jp/svd/eqev/data/nteq/fig/kako.png

[hi-v-rocknroll]

I'm wondering which is worse: alarm fatigue and the next deadly event without a sufficient evacuation, or this event happening without an alarm. People die just from evacuating. Suppose there are 1 death/1e8 km traveled from car crashes, the average evacuation distance were 150 km, and 200k people relocated. The expectation is 0.3 people would die from the evacuation in car crashes. It's possible evacuations are more dangerous and chaotic, and more stressful to the elderly who are more likely to die for this reason rather than in an automotive collision.

[ChrisArchitect]

[dupe] https://news.ycombinator.com/item?id=41192662

[jokoon]

I wonder if climate change can lead to more earthquakes

I would say no, but it would imagine geologists would not say it's impossible?

[defrost]

What scale of change and where?

When the glaciers on the modern UK melted away the entire regional landmass lifted up by hundreds of feet as the weight of kilometer+ thick ice was removed.

If you're looking at mass and force acting on fault prone areas then the addition or removal of significant pressure will have an effect on slippage and lead to changes in earthquake frequency.

[ghthor]

Activity on the sun is the main driver of earthquakes.

[pvaldes]

Is obvious that it will do.

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

[jrmcauliffe]

I didn't realise we had 18 mile depths.

[sparky_z]

To be clear, that's not referencing ocean depth to the sea floor. It means the epicenter is located 18 miles down inside the Earth's crust.