Edit: Found the answer, this was the second or third eruption from this volcano. So yeah they where already monitoring it. Amazing how they can manoeuvre these camera satellites now.
https://rammb.cira.colostate.edu/ramsdis/online/loop.asp?dat...
This looks to be zoomed way closer than your link, you can see small waves on the ocean etc. I did not think you could film the whole face of the earth at that resolution?
Edit: Or are those small waves actually large clouds?
And the comment was made that if the pyroclastic flow reached them, the first they would know about it, at night, was when the runway lights vanished.
Very different from magma gently flowing out.
The US Stormwatch image does seem to be cropped from Himawari. The size here may be deceptive, the spatial resolution is not as high as it looks because this cloud is so large.
Although the GOES ABI (and related Himawari AHI) are static designs that image the full planet from a fixed position (i.e. there is no aiming or steering as is sometimes the case in other remote sensing satellites), they do deal with practical limitations related to readout and downlink capacity. As a result they typically produce a full-disk image every 5 minutes but both are capable of producing more frequent images of selected regions (areas of interest) on command. This capability is mostly used for maintenance purposes (e.g. registration calibration) rather than for weather observations.
Incidentally NOAA is preparing to launch a new GOES satellite, GOES-T which will become GOES-18, in somewhat over a month. It is the same basic generation as GOES-16 and GOES-17 currently in primary use, including the same basic ABI, but has a minor "bugfix" to the ABI design that will avoid a problem GOES-16 and GOES-17 have that requires them to go into a reduced readout rate mode some of the time for thermal management reasons.
My basic meteorology knowledge is somewhat limited but I believe what appear to be waves are cirrus clouds. This is somewhat confirmed by their significantly increased prominence along the shockwave front, as large shockwaves in the atmosphere cause some additional formation of condensation clouds due to the increased pressure, and these tend to be cirrus up at high altitude (the condensation immediately freezes into small crystals).
However, the lifetime of the satellite is generally limited by the amount of propellant (or whatever), after it's run out the satellite is useless. So it's not done on a whim.
> ... when the satellite passes over it ...
GEO satellites don't "pass over" anything by definition. They permanently float in the air 35786km above a designated spot along equator(complicated). So GP is clearly not talking about GEO satellites.
Look at the SpaceX launch of DART. They needed a whole rocket to lift a tiny payload due to needing to turn roughly 45 degrees