The only info I have is that the 'blockage' (my word, I haven't heard of hvo quantifying what they think is the cause) is apparently preventing magma from entering the east rift plumbing system. As can be seen on the tilt plot at
http://hvo.wr.usgs.gov/kilauea/update/deformation.html the summit is inflating and deflating as Puu Oo remains flat. In other words there appears to be a break in the hydraulic connection between the summit and the rift. With the assumption that Kilauea keeps getting a fresh supply of magma from its deeper source, this results in an overall inflation of the mountain in the summit region, whereas in what we have been calling usual times, the vent down at Puu Oo has acted as a pressure relief valve (that is almost 2000 feet lower on the mountain than the summit), so even with the vent open at Puu Oo it has been unusual to see magma so close to the surface of the summit for the last year and a half.
Currently, with this blockage the pressures usually weened off of the system through the east rift are accumulating within the summit alone. What this means for the immediate future is anyones guess. The tilt at the summit is far from linear, i.e., it is not just inflating as if it were taking on more and more pressure (magma), but rather going through cycles of inflation and deflation, as if magma is moving around within the summit. But it will take the analysis of all the tilt and gps data from the summit array of instruments to be able to even guess at what is going on, and, even if this model of a blockage is reasonable. The other logical reason for a pause in eruptive activity would be a pause in the incoming magma from the deeper source. Though I do not think the summit would be in such an inflationary mode if that were the case.
There are a few ways this can develop. Over the years the east rift plumbing system has apparently stayed open by a series of earthquakes that seem to happen in pairs, a few weeks apart, with one event occurring south of Mauna Ulu and the other south of Puu Oo. The quakes are caused by that portion of the south flank spreading, to the south, and allowing for the fissure that the magma flows through between the summit and Puu Oo to remain open. Thus this backing up of magma at the summit could create enough pressure to cause this to happen again and by doing so open the rift and allow the magma to once again flow down to Puu Oo. Then again, this could happen without the drama of the earthquakes. Or, we could see a build up of pressures that get released in the upper portion of the east rift. You'll remember that this happened a few years ago just before the beginning of the whole eruptive sequence that caused all the concern for Puna, and highway 130. And of course the desired result, at least by a few, of this 'blockage', would be that the pressures within the summit are able to accumulate to a point that the magma is able to fill up the vent in Halemaumau and we can actually witness a summit eruption, with a lava lake and occasional fountaining all from the rim of the caldera.
And of course, I could be blowing a bunch of hot air, and something entirely different could be going on. That's the fun part of the whole contemplating what a living, breathing mountain might be doing from one day to the next!
As far as my pics go. I was in one capacity or another associated with hvo for about 10 years, from '85 through '95, and they have books filled with slides shot by me on their behalf during that time. As well as all of my published books are a part of their library.
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