Vol Lecture Notes 1

Nyiragongo d r congo in a 1977 eruption lava is

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Unformatted text preview: . Congo. In a 1977 eruption, lava is reported to have flowed at velocities as high as 60 km/hr killing perhaps thousands. Mafic Lavas A’a Pahoehoe Pillow Lavas 5 A’a & Pahoehoe Pillow Lava 6 Formation of Pillow Lavas Pillow lavas are restricted to submarine and subglacial flows. subglacial Form where water rapidly quenches a skin or crust that forms a ‘balloon’ that containing liquid lava. New pillows form by budding from cracks of parent pillows. Restricted to relatively low effusion rates. Pahoehoe-like sheet flows form at high effusion rates Morphology of Subareal Mafic Lavas Pahoehoe Smooth flow surfaces Flow advances by budding new toes in bulldozer fashion A’a Very rough, clinkery, brecciated surface composed of irregular cindery blocks with razor sharp asperities Form as crust breaks and is effectively ground during flow Blocky Similar to ‘a’a, but surface blocks are bigger (meters vs. cm to 10’s cm...
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This document was uploaded on 03/04/2014 for the course EAS 458 at Cornell.

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