Cosiguina
Encyclopedia
Cosigüina is a stratovolcano
located in the western part of Nicaragua
. It forms a large peninsula extending into the Gulf of Fonseca
. The summit is truncated by a large caldera, 2 x 2.4 km in diameter and 500 m deep, holding a substantial crater lake
(Laguna Cosigüina). This cone has grown within an earlier caldera, forming a somma volcano
. The earlier caldera rim is still exposed on the north side, but has been buried by the younger cone elsewhere.
The volcano has been quiet since 1859, only an instant in terms of geological time. An earthquake swarm was measured near Cosigüina in 2002, indicating that tectonic forces are still active in the region although the volcano is somewhat isolated from the line of more recently active Central American volcanoes to the northwest and southeast. The only indicators of hydrothermal activity at the volcano are intermittently observed gas bubbles in Laguna Cosigüina and a hot spring along the eastern flank of the volcano. The fairly uniform vegetation cover on the volcano’s sides also attests to a general lack of gas emissions or “hot spots” on the 872-meter-high cone.
Stratovolcano
A stratovolcano, also known as a composite volcano, is a tall, conical volcano built up by many layers of hardened lava, tephra, pumice, and volcanic ash. Unlike shield volcanoes, stratovolcanoes are characterized by a steep profile and periodic, explosive eruptions...
located in the western part of Nicaragua
Nicaragua
Nicaragua is the largest country in the Central American American isthmus, bordered by Honduras to the north and Costa Rica to the south. The country is situated between 11 and 14 degrees north of the Equator in the Northern Hemisphere, which places it entirely within the tropics. The Pacific Ocean...
. It forms a large peninsula extending into the Gulf of Fonseca
Gulf of Fonseca
The Gulf of Fonseca , part of the Pacific Ocean, is a gulf in Central America, bordering El Salvador, Honduras and Nicaragua.-History:Fonseca Bay was discovered in 1522 by Gil Gonzalez de Avila, and named by him after his patron, Archbishop Juan Fonseca, the implacable enemy of Columbus.In 1849, E. G...
. The summit is truncated by a large caldera, 2 x 2.4 km in diameter and 500 m deep, holding a substantial crater lake
Crater lake
A crater lake is a lake that forms in a volcanic crater or caldera, such as a maar; less commonly and with lower association to the term a lake may form in an impact crater caused by a meteorite. Sometimes lakes which form inside calderas are called caldera lakes, but often this distinction is not...
(Laguna Cosigüina). This cone has grown within an earlier caldera, forming a somma volcano
Somma volcano
A somma volcano is a volcanic caldera that has been partially filled by a new central cone. The name comes from Mount Somma , a stratovolcano in southern Italy with a summit caldera in which the cone of Mount Vesuvius has grown.A number of the world's best examples of somma volcanoes are found on...
. The earlier caldera rim is still exposed on the north side, but has been buried by the younger cone elsewhere.
Activity
The volcano last erupted in 1859, but its most famous activity occurred on 20 January 1835, when it produced the largest historical eruption in Nicaragua. Ash from the 1835 eruption has been found in Mexico, Costa Rica, and Jamaica.The volcano has been quiet since 1859, only an instant in terms of geological time. An earthquake swarm was measured near Cosigüina in 2002, indicating that tectonic forces are still active in the region although the volcano is somewhat isolated from the line of more recently active Central American volcanoes to the northwest and southeast. The only indicators of hydrothermal activity at the volcano are intermittently observed gas bubbles in Laguna Cosigüina and a hot spring along the eastern flank of the volcano. The fairly uniform vegetation cover on the volcano’s sides also attests to a general lack of gas emissions or “hot spots” on the 872-meter-high cone.