A bit of not-so-trivial trivia...
When flows were approaching Pāhoa in late 2014, many were very very
concerned at the prospect of destruction. I observed that the lava
flowing was black and pasty, and believed that it would stop. No
scientific training supported my supposition, just guessing based on
field observations of past flows. The Pāhoa flow had traveled quite
far from PO, and so had cooled off so very slightly (just a few
degrees). That cooling was enough to change the character of the
lava. Rather than the glistening silver fresh flows we see on the
coast, the pasty black ones crept along and stagnated rapidly.
See the attached photo of a flow in Leilani. Preliminary chemistry
apparently indicates that the erupting lava has been stored in dikes
since 1955, and is being pushed out in front of PO lavas by the
fresher magma intruded uprift. So the lava stored in the rift is
chemically distinct from PO because of crystallization of various
minerals over time, and is a bit cooler. Thus we see the pasty black
flows in Leilani, rather than the hot, very liquid, silver phh flows
weʻve been used to seeing on the main flow field.
Some expect that if the eruption continues as expected, eventually
fresh PO lava will be seen. Maybe. Or not. Or...
ALSO, for you GEONerds, Iʻve put a few articles about dikes in the LL
in the Kilauea 2018 folder. Kinda dense reading, but a few pretty
pictures and charts in there too.
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