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Nicaragua Volcanoes and Volcanics

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Major Volcanoes of Nicaragua

The scenic 7-kilometer-wide, lake-filled Apoyo caldera is a large silicic volcanic center immediately southeast of Masaya caldera. The surface of Laguna de Apoyo lies only 78 meters above sea level; the steep caldera walls rise about 100 meters to the eastern rim and up to 500 meters to the western rim. An early shield volcano constructed of basaltic-to-andesitic lava flows and small rhyodacitic lava domes collapsed following two major dacitic explosive eruptions. The caldera-forming eruptions have been radiocarbon dated at about 23,000 years before present. Post-caldera ring-fracture eruptions of uncertain age produced lava flows below the scalloped caldera rim. The younger slightly arcuate, north-south-trending La Joya fracture system that cuts the eastern flank of the caldera only 2 kilometers east of the caldera rim is a regional fissure system structurally unrelated to Apoyo caldera.

Apoyo Caldera lies within the northwest-southeast Nicaraguan Depression, at its intersection with a north-south graben (Sussman, 1985). Several of the north-south graben faults pass through and just east of Apoyo Caldera, between the caldera and the town of Granada.

Basaltic and andesitic lava flows built a broad shield during Pleistocene, and dacitic domes intruded that pile, one approximately 90,000 years B.P. Shortly before collapse, rholeiitic basalt lavas and scoria were erupted along north-south fracutres cutting the shield and a pyroclastic plateau to the east of Apoyo. From abut 23,000 to 21,000 years B.P., about 11 cubic kilometers of dacite magma was erupted in two Plinian eruptions, resulting in caldera collapse. A small volume of postcaldera andesitic lava was extruded along the ring faults, and the Granada cinder cones grew along a fissure about 2 kilometers east of Apoyo (Walker, 1981, 1982; Sussman, 1985).

The San Cristóbal volcanic complex, 100 kilometers northwest of Managua, consists of five principal volcanic edifices. The symmetrical youngest cone, San Cristóbal (also known as El Viejo) is the highest peak of the Maribios Range, and is capped by a 500 x 600 meter wide crater. El Chonco, with several flank lava domes, is located 4 kilometers to the west of San Cristóbal; it and the eroded Moyotepe volcano, 4 kilometers to the northeast of San Cristóbal, is of Pleistocene age. Volcan Casita, containing an elongated summit crater, lies immediately east of San Cristóbal and was the site of a catastrophic landslide and lahar in 1998. The Plio-Pleistocene La Pelona caldera is located at the eastern end of the San Cristóbal complex. Historical eruptions from San Cristóbal, consisting of small-to-moderate explosive activity, have been reported since the 16th century. Some other 16th-century eruptions attributed to Casita volcano are uncertain and may pertain to other Maribios Range volcanoes.

For More 1998 Casita Information

Cerro Negro, (726 meters) Central America's youngest volcano, was born in April 1850 and has been one of the most active volcanoes in Nicaragua. Cerro Negro is the most recent of a group of four very young cinder cones in the central Maribios Range 5 kilometers northwest of Las Pilas volcano. Strombolian eruptions at intervals of a few years to several decades have constructed a 500-meter-high basaltic cone and an associated lava field. Cerro Negro is one of the best-known examples of a cinder cone that has erupted more than once. Its frequent discrete eruptions, separated by long quisecent periods, are in contrast to many other cinder cones, like Paricutin in Mexico, that were formed during a single long-term eruption.

Volcan Concepción (1,700 meters) is one of Nicaragua's highest volcanoes and is also one of its most active. The symmetrical volcano forms the northwest half of the dumbbell-shaped island of Ometepe in Lake Nicaragua. Concepción is connected to neighboring Madera volcano by a narrow isthmus. north-south-trending fractures cutting across the volcano are associated with spatter cones, cinder cones, and maars located on the middle north flank and on the lower south flank down to Lake Nicaragua. Concepción has had frequent moderate explosive eruptions in the past century, most of which have originated from a small summit crater.

Concepción is one of Nicaragua's highest and most active volcanoes. The symmetrical cone occupies the northeastern half of a dumbbell-shaped island called Isla Ometepa. The dormant volcano, Maderas, occupies the southwest half of the island. A narrow isthmus connects Concepción and Maderas volcanoes. Concepción volcano towers more than 1,600 meters above Lake Nicaragua and is within 5 to 10 kilometers of several small towns situated on its aprons at or near the shoreline. These towns have a combined population of nearly 5,000. The volcano has frequently produced debris flows (watery flows of mud, rock, and debris -- also known as lahars when they occur on a volcano) that could inundate these nearby populated areas.

Concepción volcano has erupted more than 25 times in the last 120 years. Its first recorded activity was in AD 1883. Eruptions in the past century, most of which have originated from a small summit crater, comprise moderate explosions, ash that falls out of eruption plumes (called tephra), and occasional lava flows. Near the summit area, there are accumulations of rock that were emplaced hot (pyroclastic deposits), most of which were hot enough to stick together during deposition (a process called welding). These pyroclastic rocks are rather weak, and tend to break apart easily. The loose volcanic rock remobilizes during heavy rain to form lahars. Volcanic explosions have produced blankets of tephra that are distributed downwind, which on Isla Ometepe is mostly to the west. Older deposits at the west end of the island that are up to 1 meter thick indicate larger explosive events have happened at Concepción volcano in prehistoric time. Like pyroclastic-flow deposits, loose tephra on the steep slopes of the volcano provides source material that heavy rainstorms and earthquakes can mobilize to trigger debris flow.

North-south-trending fractures cutting across the volcano are associated with small volcanic flank vents called spatter cones, cinder cones, and maars located on the middle north flank and on the lower south flank of Concepción volcano down to Lake Nicaragua. Immature soils on deposits of fine ash to the west of these vents show that several of them have been active within recent prehistoric time.

The Las Pilas volcano complex, overlooking Cerro Negro volcano to the northwest, includes a cluster of cones, of which Las Pilas (El Hoyo) is the largest (1,050 meters). A north-south fracture system cutting Las Pilas has produced numerous well-preserved flank vents, including maars. The lake-filled Asososca maar is located adjacent to the conical Cerro Asososca cone on the southern side of the fissure system, south of the axis of the Maribios Range. Two small maars west of Lake Managua are located at the southern end of the fissure. Aside from a possible eruption in the 16th century, the only historical eruptions of Las Pilas took place in the 1950's from a fissure that cut the eastern side of the 700-meter-wide summit crater and extends down the north flank.

Masaya (635 meters) is one of Nicaragua's most unusual and most active volcanoes. It is a broad, 6 x 11 kilometer basaltic caldera with steep-sided walls up to 300 meters high that is filled on its northwest end by more than a dozen vents erupted along a circular, 4-kilometer-wide fracture system. The twin volcanoes of Nindiri and Masaya, the source of historical eruptions, were constructed at the southern end of the fracture system and contain multiple summit craters. A major basaltic plinian tephra was erupted from Masaya about 6,500 years ago. Historical lava flows cover much of the caldera floor and have confined a lake to the far eastern end of the caldera. A lava flow from the 1670 eruption overtopped the north caldera rim. Masaya has been frequently active since the time of the Spanish Conquistadors, when an active lava lake prompted several attempts to extract the volcano's molten "gold." Masaya lies 20 kilometers southeast of Managua and became Nicaragua's first National Park in 1979.

Masaya is immediately southeast of a zone of transverse faulting that was active in 1972, and that is thought to be a boundary between western and eastern Nicaragua lithospheric segments (Stoiber and Carr, 1973). Masaya's magma is tholeiitic basalt, and the complex is in a section of Central America where the crust is relatively thin (Carr, 1984).

The Masaya Caldera formed as a result of plinian eruptions of tholeiitic basalt (Bice, 1980, 1985; Williams, 1983a, b). Masaya is a basaltic shield volcano situated within the caldera and has several striking, steep-walled craters at its summit.

Mombacho (1,345 meters) is a stratovolcano on the shores of Lake Nicaragua that has undergone edifice collapse on several occasions. Two large horseshoe-shaped craters formed by edifice failure cut the summit on the northeast and southern flanks. The northeast-flank scarp was the source of a large debris avalanche that produced an arcuate peninsula and the Las Isletas island group in Lake Nicaragua. Two small, well-preserved cinder cones are located on the lower northern flank. The only reported historical activity was in 1570, when a debris avalanche destroyed a village on the south side of the volcano. It is not certain that the avalanche was accompanied by an eruption. Fumarolic fields and hot springs are found over a large area.

Mombacho volcano, at 1,350 meters, is situated on the shores of Lake Nicaragua and about 12 kilometers south of Granada, a city of about 90,000 inhabitants. Many more people live a few kilometers southeast of Granada in 'las Isletas de Granada and the nearby 'Peninsula de Aseses. These areas are formed of deposits of a large debris avalanche (a fast moving avalanche of rock and debris) from Mombacho. Several smaller towns with population, in the range of 5,000 to 12,000 inhabitants are to the northwest and the southwest of Mombacho volcano. Though the volcano has apparently not been active in historical time, or about the last 500 years, it has the potential to produce landslides and debris flows (watery flows of mud, rock, and debris -- also known as lahars when they occur on a volcano) that could inundate these nearby populated areas.

Momotombo (1,258 meters) is a young stratovolcano that rises prominently above the northwest shore of Lake Managua, forming one of Nicaragua's most familiar landmarks. Momotombo began growing about 4,500 years ago and consists of a somma from an older edifice that is surmounted by a younger cone with a 150 x 250 meter crater. Young lava flows from Momotombo have flowed down the northwest flank into an unnamed, 4-kilometer-wide caldera. Momotombo has a long record of strombolian eruptions, punctuated by occasional larger explosive activity. The latest eruption, in 1905, produced a lava flow that traveled from the summit to the lower northeast base. A small black plume was seen above the crater after a 10 April 1996 earthquake, but later observations noted no significant changes in the crater. A major geothermal field is located at the southeast flank of the volcano.

The San Cristóbal volcanic complex, 100 kilometers northwest of Managua, consists of five principal volcanic edifices. The symmetrical youngest cone, San Cristóbal (also known as El Viejo) is the highest peak of the Maribios Range, and is capped by a 500 x 600 meter wide crater. El Chonco, with several flank lava domes, is located 4 kilometers to the west of San Cristóbal; it and the eroded Moyotepe volcano, 4 kilometers to the northeast of San Cristóbal, is of Pleistocene age. Volcan Casita, containing an elongated summit crater, lies immediately east of San Cristóbal and was the site of a catastrophic landslide and lahar in 1998. The Plio-Pleistocene La Pelona caldera is located at the eastern end of the San Cristóbal complex. Historical eruptions from San Cristóbal, consisting of small-to-moderate explosive activity, have been reported since the 16th century. Some other 16th-century eruptions attributed to Casita volcano are uncertain and may pertain to other Maribios Range volcanoes.

Telica, (1,061 meters) one of Nicaragua's most active volcanoes, has erupted frequently since the beginning of the Spanish era. The Telica volcano group consists of several interlocking cones and vents with a general northwest alignment. Sixteenth-century eruptions have been reported at symmetrical Santa Clara volcano, at the southwest end of the Telica group. However, its eroded and breached crater has been covered by forests throughout historical time, in contrast to Telica, whose upper slopes are unvegetated. The steep-sided cone of Telica is truncated by a 700-meter-wide double crater; the southern crater, the source of recent eruptions, is 120 meters deep. El Liston, immediately southeast of Telica, has several nested craters. The fumaroles and boiling mudpots of Hervideros de San Jacinto, southeast of Telica, form a prominent geothermal area frequented by tourists, and geothermal exploration has occurred nearby.

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