EESC1168 Lecture 12: Lecture 12 geoscience 2.13
13 Feb 2017
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Volcano disasters (5 volcanoes in the book, only discussing 3 - only worry about book material covered in class) Toba (72,000 bce): the most recent extremely large supereruption (300x. Krakatau); possibly enhanced an ice age, causing mass death of humans outside of tropical refuges. Figure 1. 1 in textbook shows scale compared to other volcanoes. Layers of volcanic ash and dust in ice cores (the younger toba tuff") and the geologic record indicate that an explosion occurred. The ice cores also indicate high amounts of hydrogen sulfide and its oxidation product, sulfuric acid. Caldera: a large depression formed by inward collapse of the volcano roof. Over the last 74,000 years, a raised area has formed inside the caldera, creating a resurgent caldera. Lake toba - this used to be a mountain, but the explosion removed it. Toba"s caldera is 30 km x 100 km x 1 km deep.
