Michoacán–Guanajuato volcanic field

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Michoacán–Guanajuato
Paricutín volcano.jpg
Paricutin cinder cone and the Cerro de Tancítaro shield volcano
Elevation 3,860 m (12,664 ft)
Location
Location Michoacán and Guanajuato, Mexico
Geology
Type Cinder cones
Last eruption 1943 to 1952

Michoacán–Guanajuato is a volcano field in central Mexico that takes the form of a large cinder cone field. The field also has numerous shield volcanoes and maars. The volcano is best known for its Jorullo and Paricutin Cinder Cones, which erupted in 1759-1774 and 1943-1952.

Morphology[edit]

The volcano field covers an area of 200 x 250 km. The volcano covers areas of both the Michoacán and Guanajuato states and contains 1400 vents, mostly cinder cones. The shield volcanoes are mostly Pleistocene in age. The cinder cones are randomly arranged and occur at low altitudes, usually on alluvial plains or on the flanks of eroded shield volcanoes. There are an average of 2.5 cinder cones every 100 km2.

Eruptions[edit]

Jorullo 1759–1774 eruption[edit]

El Jorullo was born on September 29, 1759. Earthquakes occurred prior to this first day of eruption. Once the cinder cone started erupting, it continued for 15 years...eventually ending in 1774. El Jorullo didn’t develop on a corn field like Parícutin did, but it did destroy what had been a rich agricultural area. It grew approximately 820 feet (250 meters) from the ground in the first six weeks. The eruptions from El Jorullo were primarily phreatic and phreatomagmatic. They covered the area with sticky mud flows, water flows and ash falls. All but the youngest lava flows were covered by this ash fall. Later eruptions from El Jorullo were magmatic with neither mud nor water flows. This 15 year eruption was the longest one El Jorullo has had, and was the longest cinder cone eruption known. Lava flows can still be seen to the north and west of the cinder cone. The eruption had a VEI of 4.[3]

Its current elevation is 1,320 meters (4,331 ft). El Jorullo has four smaller cinder cones which have grown from its flanks. The vents of El Jorullo are aligned in a northeast to southwest direction. Lava from these vents cover nine km2 around the volcano. Later eruptions produced lavas that had higher silica contents making them more viscous than the earlier basalts and basaltic andesite lavas. El Jorullo's crater is about 1,300 by 1,640 feet (400 by 500 meters) wide and 490 feet (150 meters) deep.

Drawing of El Jorullo

Paricutin 1943–1952 eruption[edit]

The volcano began as a fissure in a cornfield owned by a P'urhépecha farmer, Dionisio Pulido, on February 20, 1943. Pulido, his wife, and their son all witnessed the initial eruption of ash and stones first-hand as they ploughed the field. The volcano grew quickly, reaching five stories tall in just a week, and it could be seen from afar in a month. Much of the volcano's growth occurred during its first year, while it was still in the explosive pyroclastic phase. The nearby villages Paricutín (after which the volcano was named) and San Juan Parangaricutiro were both buried in lava and ash; the residents relocated to vacant land nearby.

At the end of this phase, after roughly one year, the cinder cone had grown 336 meters (1,100 ft) tall. For the next eight years the volcano would continue erupting, although this was dominated by relatively quiet eruptions of lava that would scorch the surrounding 25 km² (9.7 mi²) of land. The cinder cone's activity would slowly decline during this period until the last six months of the eruption, during which violent and explosive activity was frequent. In 1952 the eruption ended and Parícutin went quiet, attaining a final height of 424 meters (1,391 ft) from the cornfield where it began. Like most cinder cones, Parícutin is believed to be a monogenetic volcano, which means that once it has finished erupting, it will never erupt again. Any new eruptions in the volcanic field will erupt in a new location.

Three people died as a result of lightning strikes caused by the eruptions, but no deaths were attributed to the lava or asphyxiation.

Gallery[edit]

References[edit]

External links[edit]