Geology Reference
In-Depth Information
Figure 8.8. Maasaw Patera, Io, displays dark lava
flows that radiate
from the caldera, forming a low-pro
le shield volcano. The caldera is
50 km by 25 km (NASA Voyager 1 199J1+000).
Figure 8.10. This image shows dark lava that
owed over smooth
plains; the bright white zone around the
ow is SO
2
“
of
the plains by the hot
flow and deposited as frost (NASA Voyager 1
75J1+000).
cooked out
”
Local eruptions of liquid sulfur are likely to occur in
addition to the major styles of eruptions outlined above.
Sulfur and sulfur compounds are common and some are
probably deposited by fumarolic activity. Because sulfur
has a low melting temperature, it is probably mobilized by
heat from silicate eruptions to produce
flows of sulfur.
This process was documented on the
flank of Mauna Loa
volcano in Hawaii and accounts for local
flows of nearly
pure sulfur.
The extensive explosive eruptions lead to signi
cant
loss of mass from Io. It is estimated that some 10 tons/s
of sulfur and sulfur dioxide escape from Io. Much of
this material is caught by Jupiter
'
is magnetic
field, where
it forms a donut-shaped
“
torus
”
enveloping the orbital
path of Io.
Figure 8.9.
-shaped volcanoes Apis Tholus (upper right)
and Inachus Tholus (center) on Io probably formed from very
fluid
lavas that spread evenly from the vents (bright central zones); the
area shown is 600 km by 800 km (NASA Voyager 1 71J1+000).
“
Pancake
”
