The AD 1250 El Metate shield volcano (Michoacan): Mexico's most voluminous Holocene eruption and its significance for archaeology and hazards

摘要

The Michoacan-Guanajuato Volcanic Field is the largest subduction-related monogenetic volcanic field in the world and includes more than 1000 scoria cones and a few hundred medium-sized volcanoes. Although medium-sized volcanoes (domes and shields) are less abundant, hazards associated with the renewal of this type of activity should not be neglected. Here, we focus on El Metate volcano, the morphologically youngest shield of the field. This volcano has a minimum volume of similar to 9.2 km(3) DRE, and its viscous lava flows were emplaced during a single eruption over a period of similar to 30 years covering an area of 103 km(2). El Metate is thus best labeled as a monogenetic andesite shield. This eruption had a significant impact on the environment (modification of the hydrological network, forest fires, etc.), and hence, nearby human populations probably had to migrate. New C-14 dates for the eruption yield a young age (similar to AD 1250), which briefly precedes the initial rise of the Tarascan Empire (AD 1350-1521) in this region. By volume, this is certainly the largest eruption during the Holocene in the Trans-Mexican Volcanic Belt, and it is the largest andesitic effusive eruption known worldwide for this period. Such a large volume erupted in a relatively short time bears important implications for evaluating future hazards in the Michoacan-Guanajuato Volcanic Field.