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
Pillow Lavas 5 A’a & Pahoehoe Pillow Lava 6 Formation of Pillow Lavas Pillow lavas are restricted to submarine and
Form where water rapidly
quenches a skin or crust
that forms a ‘balloon’
containing liquid lava.
New pillows form by
budding from cracks of
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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- Fall '06
- Basalt, lava flows, pahoehoe, Lava dome, Lava Flow Velocities