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Popocatepetl

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Introduction Popocate'petl is a volcano found in Mexico that I have been following for 3 months. It is the result of a continental-oceanic plate convergence (fig. 1). When the oceanic lithosphere (the Rivera and Cocos plates) collide with the continental lithosphere (the North American plate), the oceanic plate will descend into the subduction zone. Subduction zones generate a lot of igneous magma that rises to the surface to form volcanic mountains. I will discuss the geologic history of Popocate'petl, the subduction of the Cocos and Rivera plates, and the most current eruptions of Popocate'petl.

Fig. 1. Oceanic-continental convergence (from Pidwirny, 2001) Popocate'petl is a 5,465-meter andesitic stratovolcano that is located 19.02 degrees north and 98.62 degrees west. It is approximately 55 km east of Mexico City and 45 km east of Puebla (Fig. 2).

Fig. 2. Major Volcanoes of Mexico (from USGS/CVO, 1998) The volcano covers 500 square kilometers and has a 900-meter crater that is 200 meters deep. Popocate'petl means "Smoking Mountain," in the Aztec language of Nahuatl (Dunlap, 1996). It is the second highest peak in Mexico and is one of the country's most volatile volcanoes (Dunlap, 1996). It has had approximately 30 eruptions in historical time, mostly mild to moderate Vulcanian eruptions. Popocate'petl has also produced several Plinian type eruptions, and there are records of at least three enormous ones in the past 5,000 years (Ray, 2001).

Subduction of Cocos & Rivera Plates Popocate'petl is part of the Trans-Mexico Volcano Belt (TMVB) (fig. 3). "Volcanic activity related to the Trans-Mexican Volcanic Belt started during Early stratovolcano Miocene" (Capral, L. et al., 2000). "The TMVB is 1200 kilometers long and goes from the Gulf of California all the way through Central Mexico and meets the Central American Volcano belt near El Chichon, a volcano in Chiapas, Mexico" (Johnson, 1991). This line of volcanoes is caused by the subduction of the Cocos...