The launch of a new GVP website is scheduled for Monday, May 20, 2013.
|Subregion Name:||Southern Indian Ocean|
|Volcano Type:||Shield volcanoes|
|Last Known Eruption:||2004|
|Summit Elevation:||1230 m||4,035 feet|
|Marion Island, South Africa's only historically active volcano, lies at the SW end of a submarine plateau immediately south of the SW Indian Ocean Ridge, opposite Prince Edward Island. The low profile of 24-km-wide dominantly basaltic and trachybasaltic Marion Island is formed by two young shield volcanoes that rise above a flat-topped submarine platform. The 1230-m-high island is dotted by about 150 cinder cones, smaller scoria cones, and coastal tuff cones. The earliest dated eruptions took place about 450,000 years ago, but much of the island is covered by Holocene aa and pahoehoe lava flows, and more than 130 scoria cones formed during the Holocene. Many of these appear younger than the 4020 BP peat layer overlying one of the flows (Verwoerd, 1981). Young unvegetated lava flows appear to be only a few 100 years old (Verwoerd, 1967). The first historical eruption, during 1980, produced explosive activity and lava flows from a 5-km-long fissure that extended from the summit to the west coast.|