http://www.washingtonpost.com/blogs/capital-weather-gang/wp/2014/09/03/nasa-satellite-captures-incredible-extent-of-tavurvur-volcano-ashfall/

Self promoting this video and sending it back into the queue for one more try; last queued Friday, September 5th, 2014 9:08pm PDT - promote requested by original submitter eric3579.

*water

Adding video to channels (Water) - requested by ant.

shock waves are not limited to the speed of sound though right.. how did you figure it

I went with speed of sound. Any idea how to figure it?

-edit-
Removed my attempt at figuring the distance for a more interesting video of the volcano erupting

so minimally that far... this was pretty good from wiki:

Shock waves form when the speed of a fluid changes by more than the speed of sound.[3] At the region where this occurs sound waves travelling against the flow reach a point where they cannot travel any further upstream and the pressure progressively builds in that region, and a high pressure shock wave rapidly forms.

Shock waves are not conventional sound waves; a shock wave takes the form of a very sharp change in the gas properties on the order of a few mean free paths (roughly micrometers at atmospheric conditions) in thickness. Shock waves in air are heard as a loud "crack" or "snap" noise. Over longer distances a shock wave can change from a nonlinear wave into a linear wave, degenerating into a conventional sound wave as it heats the air and loses energy. The sound wave is heard as the familiar "thud" or "thump" of a sonic boom, commonly created by the supersonic flight of aircraft.

When the Earth pops a zit...

Watched it 3 times. *quality post.

Boosting this quality contribution up in the Hot Listing - declared quality by deedub81.

I've always wondered how cool it would be to see something that destructive first hand. I just changed my mind.

House size chunks of rock to not belong flying a mile up in the sky and closing on my position fast.

There are some more videos out there of this eruption which are wicked as well. Stuff making it all the way to the sea.

The volcano is here - https://goo.gl/maps/LbKHf

They appear to be somewhere in the middle of the bay, which makes it about 4km (?) away. If you assume (like the yt commenters did) that the shockwave slowed to the speed of sound almost instantly you would calculate a distance of approx 4-4.5kms which would have them almost on the opposite shoreline (or even on land) which they clearly are not...

p.s. Yes I realise that a supersonic shockwave should cause you to underestimate rather than overestimate distances, perhaps they're really a bit further from Rabul than I assumed?

p.p.s They were staying at Kokopo Beach Bungalows, and went out on the boat for a better look.