Update: Phil Plait has an awesome analysis of the blast from the video below that you should read.
The below video happened on August 29th. This was captured at the initial instant the volcano began errupting. I've never seen the initial blast of this type of volcano erupting before.
Pay close attention to:
- The shockwave of the blast
- The massive rocks and soil that were thrown into the air and splashed into the ocean around the volcano
- The fact that these rocks were still airborne and flying before the sound of the blast