Mount Hudson
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| Mount Hudson | |
|---|---|
 Aerial photo from 1991 |
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| Elevation | 1,905 metres (6,250 feet) |
| Location | Chile |
| Range | Andes |
| Coordinates | |
| Type | Stratovolcano |
| Last eruption | 1991 |
Mount Hudson (locally known as Cerro Hudson) is a stratovolcano in southern Chile, and the site of one of the largest eruptions in the twentieth century. The mountain itself is covered by a glacier. There is a caldera at the summit from an ancient eruption; modern volcanic activity comes from inside the caldera.
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[edit] Historical eruptions
Large eruptions around 4750 BCE and 1890 BCE are believed to have been of Volcanic Explosivity Index (VEI) 6; these are probably responsible for the large caldera. Recently, the volcano has had moderate eruptions in 1891 and 1971 as well as a large eruption in 1991.
[edit] 1971 eruption
Before 1970, little was known about the mountain. Minor eruptive activity began in 1970 and melted parts of the glacier, raising river water levels and leading to the identification of the caldera. In August-September of 1971, a moderate eruption (VEI 3) located in the northwest area of the caldera sent ash into the air and caused lahars from the melting of a large portion of the glacier. The lahars killed five people; many more were evacuated.
[edit] 1991 eruption
The eruption in August to October 1991 was a large plinian eruption that ejected 2-6 cubic km of material (a VEI of 5). Parts of the glacier melted and ran down the mountain as mud flows (see glacier run). Due to the remoteness of the area no humans were killed but hundreds of people were evacuated from the vicinity. Ash fell on Chile and Argentina as well as in the South Atlantic Ocean and on the Falkland Islands.
In addition to the ash, a large amount of sulfur dioxide and other aerosols were ejected in the eruption. These contributed to those already in the atmosphere from the even larger Mount Pinatubo eruption earlier in the year and helped cause a worldwide cooling effect over the following years. Ozone was also depleted, with the Antarctic ozone hole growing to its largest levels ever recorded in 1992 and 1993.
As a result of the Pinatubo eruption, the Hudson eruption received little attention at the time.
