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Cerro Blanco (volcano)
Cerro Blanco (also known as ''Robledo'') is a caldera in the Andes of the Catamarca Province in Argentina. Part of the Central Volcanic Zone of the Andes, it is a caldera located at an altitude of in a depression. The caldera is associated with a less well defined caldera to the south and with several lava domes.
Cerro Blanco has been active for the last eight million years with several ignimbrites. One of the most recent eruptions occurred 73,000 years ago and formed the Campo de la Piedra Pómez ignimbrite layer. About 5,000 years ago, the largest volcanic eruption of the Central Andes with a volcanic explosivity index of 7 occurred at Cerro Blanco, forming the most recent caldera as well as thick ignimbrite layers. About of rhyolite were erupted then. The volcano is dormant since then with some deformation and geothermal activity. A major future eruption would put local communities to the south at risk.
Cerro Blanco is also known for giant ripple marks that have formed on its ignimbrite fields. Persistent wind action on the ground has shifted gravel and sand, forming wave-like structures. These ripple marks have heights up to one metre and are separated by distances up to thirty metres. Unlike dunes they do not migrate with the wind and are stationary. These ripple marks are among the most extreme on Earth and have been compared to Martian ripple marks.
== Geography and geology ==
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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