Volcano Presentation
Transcript: Volcano Presentation El Chichon Patzy Carmona Location: It is in northwestern Chiapas, Mexico. 17.360°N / 93.228°W It is a lava dome A steep-sided mass of viscous and commonly blocky lava extruded from a vent; typically has a rounded top and roughly circular outline History: The first erruption happened around 550, then in 900, 1250, 1500, 1600, 1900, 2000, 2500, 3100, 3700 and 7700 years BC El Chichon’s most famous eruption was in 1982. It lasted from March 28 to April 4, 1982. It generated pyroclastic surges and flows that dammed adjacent drainages including the Magdalena River. This created a 4 km long and 40 km wide lake that drained catastrophically and inundated the town of Ostuacan with a mixture of hot water and pyroclastic sediment. The eruption on April 3rd that let out pyroclastic surges and flows killed more than 2000 inhabitants. The eruption was unique due to the release of unusually large amounts of sulfur into the atmosphere. Three weeks after the eruption, the volcanic aerosol had circled the Earth and severely affected aircraft particularly in the northern hemisphere. Pyroclastic flows and surges destroyed nine villages south of the volcano. Cultural Significance: The eruptive history of El Chichón also offers clues in the investigation of the Maya civilization. Several researchers have considered the volcano as an important factor in the answer to some intriguing questions such as the extensive use of volcanic ash in Late Classic Maya ceramics or, of greater importance, the causes of the collapse of the Classic Maya civilization. Structure and Composition: Summit elevation is 3,773 ft The former summit of the volcano was constructed within a 1.6 x 2 km summit crater created about 220,000 years ago. The eruptions in 1982 created a new 1-km-wide, 300-m-deep crater that now contains an acidic crater lake. The magma erupted by El Chichon have a trachyandesitic composition with a similar mineral association of plagioclase, amphibole, augite, magnetite, sphene, pyrrothite, biotite, and apatite. Status: Even though it is famously known for the large eruption in 1982, it is not very large and not very active. The origin of El Chichón volcano has been related to the subduction of the Cocos plate beneath the North American plate at the Middle American Trench. This ongoing subduction process is occurring at an average convergence rate of 66 mm/yr in a northeast direction. The projected slab is dipping at an angle of 40° and has an approximate thickness of 39 km. This geometry sets El Chichón, which is at 400 km from the trench to about 300 km above the subducted slab under Chiapas. Properties: El Chichon is known for its felsic magma. The powerful 1982 explosive consisted of high-sulfur, anhydrite-bearing magma, and was accompanied by pyroclastic flows and surges that devastated an area extending about 8 km around the volcano. Works sited: Cain, F.C. (2009, June 5). El chichon volcano. Retrieved from http://www.universetoday.com/32071/el-chichon-volcano/ Stanbrough, L.S. (2007, February 18). El chichon eruption - april 1982, mexico. Retrieved from http://www.interragate.info/notable-past-event/3787 Espíndola, J. M. E. (2000). Volcanic history of el chichón volcano (chiapas, mexico) during the holocene, and its impact on human activity. Retrieved from http://adsabs.harvard.edu/abs/2000BVol..62..90E Type: Formation: