Masaya Volcano
From Wikipedia, the free encyclopedia
| Masaya Volcano | |
|---|---|
 View of the crater in 2002 |
|
| Elevation | 635 metres (2,083 feet) |
| Location | Masaya, Nicaragua |
| Range | Central American Volcanic Belt |
| Coordinates | |
| Type | Stratovolcano |
| Age of rock | ~2500 years |
| Last eruption | 2003 |
Masaya is a large basaltic volcanic caldera located 20 km south of Managua, Nicaragua, Central America and is Nicaragua's first and largest National Park. The volcanic complex is composed of a nested set of calderas and craters, the largest of which is Las Sierras shield and caldera. Within this caldera lies Masaya Volcano sensu stricto, a shallow shield composed of basaltic lavas and tephras. This hosts Masaya caldera, formed 2500 years ago by an 8-km³ basaltic ignimbrite eruption. Inside this caldera a new basaltic complex has grown from eruptions mainly on a semi-circular set of vents that include the Masaya and Nindiri cones. The latter host the pit craters of Masaya, Santiago, Nindiri and San Pedro. Observations in the walls of the pit craters indicate that there have been several episodes of cone and pit crater formation.
The floor of Masaya caldera is covered by poorly vegetated lavas, indicating resurfacing within the past 1000 or so years, but only two lava flows have erupted since the sixteenth century. The first, in 1670, was an overflow from the Nindiri pit, which at that time hosted a 1-km-wide lava lake. The other, in 1772, issued from a fissure on the flank of the Masaya cone. Since 1772, lava has appeared at the surface only in the Santiago pit crater (presently active and persistently degassing) and possibly within Nindiri crater in 1852. During the rainy season, it is common for rainwater to percolate into the volcano, causing it to emit lots of acidic steam.
At times, Masaya emits large amounts of sulfur dioxide gas. Sulfur dioxide has been released from the Santiago Crater in large quatities and volcanologists studied these events to better understand the impact of acid rain and the potential for health problems.
In 1979, Masaya became Nicaragua's first National Park (Parque Nacional Volcan Masaya). It is the only volcano in the western hemisphere where you are able to drive to the rim.
Other eruptive events have occurred in the last 50 years. On 22 November 1999, the Masaya Volcano appears to have begun a new eruptive event. A hot spot appeared on satellite imagery, and there was a possible explosion. On 23 April, 2001 the crater exploded and formed a new vent in the bottom of the crater. The explosion sent rocks with diameters up to 60 cm which travelled up to 500 m from the crater. Vehicles in the visitors area were damanged and one person was injured. On Oct. 4, 2003 an eruption cloud was reported at Masaya. The plume rose to a height of ~4.6 km.1
The Masaya Volcano is located in the department of Masaya. This is Nicaragua's smallest department, inhabited by 318,000 people (2005 estimate).
[edit] External links
- Dirección General de Geofísica, INETER (in Spanish)
- Volcanoes.ca - Latin American Volcanoes page
- Global Volcanism Program information page
- ViaNica.com - Information about visiting the Masaya Volcano National Park
[edit] References
- Delmelle, P., Stix, J., Baxter, P.J., Garcia-Alvarez, J. and Barquero, J. (2002). Atmospheric dispersion, environmental effects and potential health hazard associated with the low-altitude gas plume of Masaya volcano, Nicaragua. Bulletin of Volcanology, 10.1007/s00445-002-0221-6
- Rymer, H., van Wyk de Vries, B., Stix, J., and Williams-Jones, G. (1998). Pit crater structure and processes governing persistent activity at Masaya Volcano, Nicaragua. Bulletin of Volcanology, 59, 345-355.
- Williams-Jones, G., Rymer, H., and Rothery, D.A. (2003). Gravity changes and passive degassing at the Masaya caldera complex, Nicaragua. Journal of Volcanology and Geothermal Research, 123(1-2), 137-160.
Once listed as “extinct,” Masaya volcano stands about 600 meters (2000 feet) high and lies some 30 kilometers (20 miles) southeast of Managua, capital city of Nicaragua. A lake, 5.6 kilometers (3.5 miles) long and 2.4 kilometers (1.5 miles) wide, occupies the East crater. Masaya volcano is interesting in a number of ways: It has erupted basaltic ash fall deposits of exceptional volume in the past, and the sulphurous fumes exhaled from its crater were at one time responsible for serious damage to crops over a large area downwind.
A large white eruption plume is prominent in this photograph. Its white color suggests that it is largely composed of steam and other gases rather than ash, and that it is not the result of an explosive event but rather the slow and steady release of volatiles from the subvolcanic magma chamber. Shuttle photographs of this sort offer remarkably convenient and economical means of monitoring volcanic eruption plumes and tracking their downwind dissemination.
