San Salvador (volcano)

Infobox Mountain
Name = San Salvador
Photo =SanSalvadorVolcano.jpg
Caption = The massive San Salvador volcano dominates the landscape west of the city of San Salvador. To the left, the wide 'hump' is Boquerón, while the peak to the right is El Picacho
Elevation = 1,893 metres (6,211 feet)
Location = El Salvador
Prominence =
Coordinates = coord|13.734|N|89.294|W|type:mountain
Topographic

Type = Complex volcano
Age =
Last eruption= 1917
First ascent =
Easiest route=

The San Salvador Volcano (also known as Quetzaltepec) is a complex volcano situated northwest to the city of San Salvador. The crater has been nearly filled with a relatively newer edifice, the Boquerón volcano.The city of San Salvador is adjacent to the volcano and the western section of the city actually lies among its slopes. Because of this close proximity, any geological activity of the volcano, whether eruptive or not, has the potential to result in catastrophic destruction and death to the city.Despite this, the volcano is iconic of the city, and several TV and radio antennas are situated on the El Picacho peaks and the crater of Boqueron.

an Salvador edifice

The San Salvador edifice formed more than 70,000 years ago, creating an edifice about 10 to 14km in diameter and 3000m above sea level. Later, an explosive eruptive episode called 'G-1' (about 40,000 to 50,000 years ago) formed a crater that was 4.5km by 6km in size. The Picacho and Jabali peaks are the remnants of this crater. The G-1 episode erupted a dacitic pumice effusion, likely in a plinian style eruption.

Boquerón edifice

The Boquerón edifice formed between 40,000 and 1580 years ago, filling up the G-1 eruption crater. the lavas of the Boquerón edifice contain more alkali element and iron oxide than the lavas of the san salvador edifice, allowing for a clear chemical distinction.Around 800 years ago, the present day crater was formed in a violent explosion. The crater, which gives it the present name (Boquerón means big mouth in Spanish) is 1.5km in diameter and 500m deep. Within the crater around the upper walls, crops are cultivated by the locals who live on the volcano.

The magma chamber which the volcano sits upon contains a number of fissures which protrude along the flanks and sides of the volcano. The northwest (N40W) fissure has been the most active recently, with such significant eruptive events, such as the Loma Caldera eruption which buried the ancient village of Ceren and the eruption of El Playon (1658-71) which buried the town of Nexapa. The citizens relocated to Nejapa and nowadays the eruption is celebrated annually. The most recent eruption in 1917 caused a flank eruption on the volcano along the N40W fissure. During this eruption, the crater lake inside the Boqueron evaporated and a cinder cone appeared, christened 'Boqueroncito'.

ee also

*List of volcanoes in El Salvador

References

* [http://www.volcano.si.edu/world/volcano.cfm?vnum=1403-05= Global Volcanism Program]

Williams, H., and Meyer-Abich, H., 1955 Volcanisim in the southern part of El Salvador: University of California Publication in geological Sciences v. 32 pp1-64

Sofield. D., Eruptive history and volcanic hazards of volcanic hazards of Volcan San Salvador, in Rose W.I. et al, Natural Hazards in El Salvador: Bolder, Colorado, Geological Society of America Special Paper 375, pp 147-158. Fairbrothers G E., Carr M J., and Mayfield F G., Temporal Magmatic Variation at Boqueron Volcano, El Salvador. Contrib. Mineral. Petrol. v 67, pp 1-9 (1978)

External links

* http://vulcan.wr.usgs.gov/Volcanoes/ElSalvador/Publications/OFR01-366/framework.html - Topographical hazard zonation maps regarding the volcano and the city