To summarize basic activity at Halema'uma'u, it has been consistently venting a large plume of steam, gas and ash since early March. This is technically an ongoing eruption. Very passive, basically just the de-gassing of the lava lake that is a few hundred meters below the surface. But every now and then, something explosive happens, and the tranquil white plume turns into a roiling brown mushroom cloud, showering ejecta in the immediate vicinity. Anything thrown out of a volcano during an eruption is called ejecta. This includes pulverized rock, or ash, molten lava and bits of rock ripped off the walls of the vent. Its exciting, there are usually huge flames and loud noises. The numerous seismometers around the crater all record big earthquakes.
That is a picture from a remote camera installed on the crater rim during the Tuesday afternoon eruption. I was sitting at a desk overlooking the crater at the time, but lamentably had my eyes stuck inside a microscope.
One of the things the folks at HVO do very well is put cool videos of impressive volcanic activity on their website for public display. You will enjoy these, I promise. The first is taken by a webcam sitting in the observatory atop our building, the second is taken by the crater rim camera (time-lapse, sped up).
Wow!! Damn, did you see that camera get covered in ash! Wow, cuz that's the exact spot we stand at to try and catch a glimpse of the lava lake when we do the daily ash collection. Good thing that hit when nobody was there...
The question you are all asking, I'm sure, is Why? Why does this normally passive volcano all of a sudden blast out ash, gas and lava?
I will answer that in the next post...soon to come.
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