Tuesday, November 17, 2009
Two types of lava flows, pahoehoe and a`a, are different textural forms of otherwise identical lava. The smooth-textured pahoehoe (foreground) are formed by gas-poor lava, whereas the sharp & jagged-surfaced a`a flows (the hot lava pictured) are produced during eruptions with lava coming out of gas-rich magma. Eruptions of a`a lava commonly evolve into the pahoehoe forms.
The majority of lava between the eruption site up on the mountain near Pu`u O`o crater and the ocean 6 ½ miles below are of the pahoehoe variety. But interspersed along that zone are sections of a`a that are usually avoided while hiking the terrain because a`a is very sharp and unstable; breaking underfoot like sheets of glass and just as sharp.
The photo below was my creative attempt at making an a`a sheet look not so menacing. The stars of light is the sun shinning through some puka’s (holes).
Current lava flow conditions:
Last night out off the end of the road, at the County lava viewing area, Waikupanaha ocean entry was going strong to the delight of hundreds of spectators. Surface flows, on the other hand, were quite subdued. But by 9:00 PM we began seeing some bright spots of molten lava randomly appearing across the coastal flats, as well as inland upslope locations.
The increasing surface flow sightings correspond well with the continuing up-tic of lava pressure being recorded under Kilauea Volcano, as mentioned in yesterdays posting.
Posted by Leigh at 11:04 AM