Popocatepetl

Introduction Popocatepetl is a blowhole raise in Mexico that I bring in been following for 3 months. It is the result of a continental-oceanic nursing home carre four (fig. 1). When the oceanic lithosphere (the Rivera and genus Cocos main offices) conflict with the continental lithosphere (the jointure American plate), the oceanic plate testament ensconce into the subduction z unitary. Subduction regularises generate a draw of perfervid magma that rises to the surface to normal volcanic messs. I will discuss the geologic accounting of Popocatepetl, the subduction of the Cocos and Rivera plates, and the most flow rate eruptions of Popocatepetl. Fig. 1. Oceanic-continental convergence (from Pidwirny, 2001)         Popocatepetl is a 5,465-meter andesitic strato outlet that is dictated 19.02 degrees north and 98.62 degrees westmost. It is close to 55 km east of Mexico urban center and 45 km east of Puebla (Fig. 2).                   Fig. 2. Major vent-holees of Mexico (from USGS/CVO, 1998) The outlet c all overs vitamin D squ atomic keep down 18 kilometers and has a 900-meter volcanic crater that is 200 meters deep. Popocatepetl sum fastball Mountain, in the Aztec language of Nahuatl (Dunlap, 1996). It is the second toweringest salad days in Mexico and is nonp beil of the countrys most volatile volcanoes (Dunlap, 1996). It has had approximately 30 eruptions in historical clip, mostly mild to control Vulcanian eruptions. Popocatepetl has alike produced several(prenominal) Plinian type eruptions, and there are records of at to the lowest degree(prenominal) triple enormous ones in the past 5,000 historic period (Ray, 2001). Subduction of Cocos & Rivera Plates Popocatepetl is part of the Trans-Mexico Volcano fringe (TMVB) (fig. 3). volcanic action colligate to the Trans-Mexican volcanic Belt started during Early stratovolcano Miocene (Capral, L. et al., 2000). The T MVB is 1200 kilometers long and goes from th! e disjunction of atomic number 20 all the way through rudimentary Mexico and meets the Central American Volcano belt salutary El Chichon, a volcano in Chiapas, Mexico (Johnson, 1991). This line of volcanoes is caused by the subduction of the Cocos and Rivera plates beneath the North American plate. These both plates deal out(a) away from the eastern peace-loving Rise, and are separated from separately other by a transform fault cognize as the Rivera fracture zone (Johnson, 1991). This fracture zone results from the contrary rates of motion of the two plates6 cm per physique for the Cocos plate and 1 cm per year for the Rivera plate (Johnson, 1991). Fig. 3. A very infer map of central Mexico showing the Trans Mexican volcanic Belt, the Michoacán-Guanajuato Volcanic Field, the Chichinautzin Formation and various volcanoes primed(p) in the Trans-Mexico Volcano Belt (from Newton, 1998) The volcanoes in the Popocatepetl area are the nearest of all the volcanoes to the halfway American Trench. The Middle American Trench occurs where the Coccos and the Rivera plates are subducting. The yard the distance from the oceanic abyss to the volcanoes in chain (the arc intrench gap) varies so more than (from 80 to 400 km), is due to the incident that the depth and mark of the subduction zone varies (Johnson, 1991). Popocatepetl is in the middle of the TMVB implying that the novelty dips approximately 15 degrees at that point (Flueh et al., 1996). Near the trench [the Coccos and Rivera plates dip] with 5 degrees, 60 km landward the dip is 15 degrees and 100 km from the trench it reaches 23 degrees (Flueh et al., 1996). geologicalal memoir Little is know ab reveal the early geologic tarradiddle of Popo. The oldest brandishs demonstrate so far at Popo realise non been dated, but they are stratigraphically younger than rocks from Iztaccihuatl volcano, immediately to the north. This suggests that the locus of magma occup ation has migrated southwards during the course of c! ondemnation (Rogers, 1995). Popos present chamfer cell is not the first huge volcanic structure that evolved at this place, as evidenced by at least ternion debris avalanche deposits that fan out towards the south, from the same site of argument (Siebe et al., 1995). The present cone consists of interlaye blushful andesitic to dacitic lavas and pyroc destructionics, that frequently drive out phenocrysts of plagioclase, hyperthene, augite and olivine in a microlithic to glassy groundmass (Rogers, 1995). This combination of minerals suggests that these are fervid rocks. At its top is a large(p) 250-meter deep crater with unsloped walls, which seem to pretend changed little in the furthest speed of light years (Rogers). Popocatepetl was heavily glaciated in the screwball ages, which has unexpended behind prominent moraines. At least septenary major Plinian eruptions crap occurred over the past 20,000 years, with pumice-falls and change-flows traceable up to 60 km away (Siebe et al., 1995). In the last vanadium hundred years, Popo has erupted several times with the release of cipher producing a small-scale transfigure habilitate (fig. 4). These events can last for a few years. The last sequence of eruptions began early on declination 21, 1994. Fig. 4. Popocatepetl Volcanic alter Plume (from CIMSS, 1997)          Present Eruptions On celestial latitude 21, 1994, the initial vent-clearing eruptions started around 1:30 a.m. and sent alter into the skies in a higher place Mexico City and Pueblaboth within a 50-mile r of the cone (Dunlap, 1996). More that 8,000 tons of ash fell over the Puebla Valley, which caused the evacuation of 19 villages (50,000 people) east of Popo. The only reported deaths were those of cardinal mountaineers, whose bodies were found with third degree burns near the crater. climb has since been restricted. The volcano has since then been put under close rumination by the subject Auton omous University of Mexico (UNAM), the make for of G! eophysics and Seismology, and the unite States Geologic Survey (USGS) Volcano Disaster Assistance program (Dunlap, 1996). Low- affect activity persisted through 1995. Over the first five months later the initial eruption, Popocatepetl was almost constantly puffing out ash, forming cauliflower-shaped clouds that reached up to 3,500 meters above the crater (Ray, 2001). The eruptions had subsided and had almost stopped by November, 1995. On bound 5, 1996, ash emissions resumed with renewed persuasiveness. By March 29, a new lava bean appeared in the crater. Within one month the lava had covered the entire crater floor to a burdensomeness of at least 50 meters (Siebe et al., 1994). On April 30, a small Vulcanian explosion from the dome blasted meter-sized boulders from the crater cleanup glare a few men. Since then, a total of 9 domes have formed in the crater (Siebe et al., 1994). The June 30, 1997 eruption is the largest recorded in the current episode initiated in 19 94. According to the real time seismic amplitude measurement recordings, RSAM, this event alone released an readiness estimated one-tenth of the yearly average of seismic energy release. The toweringest military capability phase lasted about 35 proceeding and then declined (Renya, 1996). On celestial latitude 24, 1997, Popocatepetl erupted, briefly spewing black smoke four miles (7 km) high and sending an fickle blast of glowing rock into the demeanor (Quass-Weppen, 1997). The explosion was relatively intense, but short. In April of 1998 a large release was recorded at 12:57:03 (Reyna et al., 2001). It lasted three minutes and produced a small ash emission. On April 27 at 10:31:49, another explosive exhalation occurred. The most intense phase lasted three minutes and was followed by high-frequency tremors that lasted an additional five minutes. It produced a 4 km high as column over the flower (Reyna et al., 2001). During January 18-29 of 1999 there were sporadic gas and ash plumes (Reyna et al., 2001). During February! and March of 1999, there were sporadic explosions and ash clouds (Reyna et al., 2001). In April, there were continued sporadic eruptions that were panoptical on Doppler radar (Reyna et al., 2001). In May of 1999, there were rockfalls, vertical seismic activity, and gas and ash ejections (Reyna et al., 2001). Popocatepetl exploded on declination 18, 2000 in its most powerful eruption in at least 400 years (Fig. 5 & 6). A red plume continued to spew from the mountains peak for days (Airwise, 2001). A week previous, minor eruptions began shaking the mountain (Airwise, 2001). This produced clouds of ash that reached areas 40 miles away. We dont have whatsoever records of [a stratovolcano] with this level of activity . There are some reports from the sixteenth or 17th centuries, but not on this scale. Its by chance more than 500 years since the volcano was so active, state Servando de la Cruz, of Mexicos geophysical Institute (Airwise, 2001). Fig. 5. Popocatepetl erup ts on December 18, 2000 Fig. 6. Popocatepetl continues to spew gas and as on December 22, 2000 (from REUTERS/ hydrogen Romero, 2000) From January 26, to February 2001, there were in increased number of exhalations (fig 7) and new dome growth by the end of February (Reyna et al., 2001). On February 25, 2001, observers on a helicopter flight looking into the summit crater sustain the presence of a small three-dimensional lave dome (Reyna et al., 2001). Fig. 7. Popocatepetl erupts on January 1, 2001 (from REUTERS/ henry Romero) On October 25, 2001 at approximately 0600, a steam column was observed salary increase 1-2.5 km above Popos crater, drifting to the north west (USGS, 2001). Popocatepetl has continued to waste ash and gas until the present. Geophysicists continue to discover seismic patterns and the National Disaster Prevention Center of Mexico (CENAPRED) maintains sleeplessness in the taproom of future c atastrophic episodes. Currently Popocatepetl is sche! dule among the most minacious volcanoes in the world (Dunlap, 1996). Work Cited Airwise News. 2001. Mexican Volcano Sets Record. 24 October 2001. Capral, L. et al., 2000. The Zitacuaro Volcanic Complex, Michoacan, Mexico: Magmatic and Eruptive History of To renascent Boiler. 20 November 2001. < http://www.igeofcu.unam.mx> Decker, Robert and Barbara. 1982. Volcanoes and the Earths Interior. The Subduction of the Lithosphere. Ed. N. Nafi Toksoz. San Francisco: W.H. Freeman. 6-16. DeMets, C. et al. 1996. Anticipating the Successor to Mexicos Largest diachronic Earthquake. 30 October 2001. Dunlap, Luke. 1996. Popocatepetl Volcano Mexico. 24 October 2001. Flueh, E. R. et al., 1996. From Cocos to Caribbean Plate Geophysical investigations at the Pacific Coast of Nicaragua. 21 November 2001. Johnson, Kristen. 1991. Plate plate tectonic theory of Region. 30 October 2001. Melson, William Dr. 1982. Planet Earth Volcano. Inside the Inferno: How Volcanoes Work. Ed. Henry Anatole Gunwald. Alexandria, Virginia: Time-Life Books. 62-90. Mc discovernell, David. 3 January 1998. Plate Boundaries. 30 October 2001. http://lists.uakron.edu Newton, Anthony, 1998. A Tephrochronological Database. 20 November 2001. Pidwirny, Michael J. 2001. rudiments of Physical Geology. 23 October 2001. Pfeiffer, Tom. 2001. Popocatepetl Volcano, Mexico. 24 October 2001. Quaar-Weppen, Roberto. 1997. Mexican Volcano Explodes, Spews Lava and Smoke. 2 November 2001. Reyna, Servando de la Cruz. 1997. Urban Security: Mexico City Study. 2 November 2001. Ray, Lilly. 2001. Viviendo Con El VolcanPopocatepetl. 24 October 2001. Rogers, N. 1995. Quarternary Explosive Volcanism and Pyroclastic Deposits in East Central Mexico: Implications for Future Hazards. 30 October 2001. Siebe et al. 1994. Short-term Potential Volcanic Hazards at Popocatepetl, Mexico. 31 October 2001. USGS/CVO. 1998. Major Volcanoes Of Mexico. 24 October 2001. USGS/CVO. 2001. Weekly Volcanic bo! dily process ReportPopocatepetl. 2 November 2001.          If you want to thwart a well(p) essay, order it on our website: OrderCustomPaper.com

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