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Australian Volcanism

Posted Feb 24 2013 12:00am
Most of the active volcanoes on Earth occur along subduction zones of the Pacific Rim and western Indonesia.  Others rise above hotspots (both oceanic and terrestrial), atop mid-oceanic ridges (Iceland) and at continental rift zones (e.g. the East African Rift and Rio Grande Rift).  Examples of these geophysical processes can be found in parts of the Americas, Europe, Asia, Africa and across the major oceans of planet Earth; however, one does not generally associate volcanism with Australia, which lies far from active plate boundaries.

Nevertheless, volcanic terrain is found throughout eastern Australia, from northern Queensland to Tasmania and South Australia.  The many volcanic centers, now extinct or dormant, were produced by a cluster of hotspots over which the Continent has moved during the past 40 million years.  Since the Australian Plate is moving slowly to the NNE, the oldest volcanic sites are in the north while the youngest are near the southern coast; indeed, the most recent volcanic eruption on the Continent occurred more than 4000 years ago, in South Australia.  Some of the southernmost volcanoes are dormant (not completely extinct) and may erupt again.

While active volcanism is not currently found on the Australian Continent, it will eventually return when a dormant volcano reactivates or in the form of a new hotspot or rift zone, either of which would be triggered by a new mantle plume.  In the meantime, Australian Territory does possess active volcanism at the Heard and McDonald Islands, a volcanic island group in the Southern Ocean, some 2500 miles southwest of Perth and 1000 miles north of Antarctica.
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