Geoscience Reference
In-Depth Information
Figure 2.11
Map showing the Antarctic
tectonic plate and its interactions with other
southern hemisphere plates including the
Scotia Sea region, based on satellite gravity
measurements. (Credit: Trond Torsvik)
spreading ridge. Deception Island had signi
cant eruptions in 1967, 1969 and 1970.
The island is around 14 km in diameter, and breached at the southeast end allowing
seawater to
fill the central caldera. Three new craters and an island were formed in
the 1967 eruption. Volcanic ejecta were erupted from a
fissure in the ice on the
caldera wall in 1969 destroying a Chilean station and severely damaging a nearby
British station. A chain of new craters was formed in 1970. Hot springs near the
shoreline of the caldera provide a perfect location for swimming and bathing and
have become a popular destination for tourists on Antarctic cruises.
The most active volcano in Antarctica is Mt Erebus, the southernmost active
volcano in the world and the largest (3795m high) of four volcanic cones that form
Ross Island. It contains a persistent lake of molten magma that produces an unusual
volcanic rock popularly called kenyte (technically known as anorthoclase phonolite,
a unique type of feldspar mineral). The only other place in the world where this
volcanic rock is found is in Kenya. Although the last major historically known
eruption occurred in 1984
85, small relatively low-level sporadic volcanic eruptions
to altitudes of tens to hundreds of metres are common from the lava lake today.
Interestingly, Mt Erebus does not sit on nor is it related to an active plate boundary,
but it is the remaining active volcano in a much larger volcanic province, the
McMurdo volcanic province, that was caused by, or in some way related to, rifting of
the continent that resulted in large parts of West Antarctic being below sea level and
uplift of the Transantarctic Mountains on the
-
flanks of the rift system.
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