Tonga volcano

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clv101
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Tonga volcano

Post by clv101 »

This is pretty dramatic, incredible videos:
https://twitter.com/pppapin/status/1482 ... UePVQ&s=09

See how rotation of Earth is faster than shockwave moving at speed of sound.

There will be significant stratospheric injection, may even be detectable global cooling like there was with Pinatubo.

Tsunami too.
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UndercoverElephant
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Re: Tonga volcano

Post by UndercoverElephant »

The size of the ash cloud is enormous, given that this volcano went off underwater.

Last picture on this page gives a clear sense of the scale: https://www.bbc.co.uk/news/world-asia-60007119
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clv101
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Re: Tonga volcano

Post by clv101 »

Went off at 0410 GMT. Probably of the order 10 MT, like a big nuclear bomb.
Satellite videos show shock wave travelling out at the speed of sound and night time approaching as the Earth rotates. Earth rotates faster so night overtakes the shockwave. But how far does the shockwave go?

Turns out *all the way*. I have a weather station in SW Wales, and this evening, around 1900 GMT, the barometer recorded a pressure blip, recorded on the graph. So it took around 15 hours to travel the 10,250 miles, so 680 miles per hour. Seems reasonable, slower than sea level, faster than high up.

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BritDownUnder
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Re: Tonga volcano

Post by BritDownUnder »

Earth has a circumference of about 24,000 miles and rotates over 24 hours so at the equator it is 1000 miles per hour. Tonga is near but not on the equator so slightly less rotational speed than 1000 mph.

Speed of sound is 760 mph at sea level and decreases slightly before increasing again with altitude due to a dependence on both pressure and temperature of air.

Apparently the Krakatoa shockwave travelled around the world three times so keep your recording up for the second one.
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PS_RalphW
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Re: Tonga volcano

Post by PS_RalphW »

I haven't seen any informed estimate of the size of the eruption, but I don't see the pressure wave making it 3 times round the globe, so I think we can assume it is smaller than Krakatoa.

The fact that the tsunami was quite small and there are no immediate reports of casualties also points to a smaller explosion, but the quantity of dust into the atmosphere may still lead to short term atmospheric cooling.
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Re: Tonga volcano

Post by clv101 »

First direct SO2 measurements come in around 0.4 mt, compared with around 18 mt for Pinatubo ('91). Pinatubo caused global cooling of ~0.6C for 15 months, so far this eruption is not of the scale to have detectable climate impacts (maybe there's more to come though?).
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Re: Tonga volcano

Post by clv101 »

My barometer saw a clear 2nd wave, I guess going around the other side, across Pacific, around 2am this morning.
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