Lake Ilopango is a

crater lake Crater Lake ( Klamath: ''Giiwas'') is a volcanic crater lake in south-central Oregon in the western United States. It is the main feature of Crater Lake National Park and is famous for its deep blue color and water clarity. The lake partly fill ...

which fills an 8 by 11 km (72 km² or 28 sq mi) volcanic

caldera A caldera ( ) is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber in a volcano eruption. When large volumes of magma are erupted over a short time, structural support for the rock above the magma chamber is ...

in central

El Salvador El Salvador (; , meaning " The Saviour"), officially the Republic of El Salvador ( es, República de El Salvador), is a country in Central America. It is bordered on the northeast by Honduras, on the northwest by Guatemala, and on the south ...

, on the borders of the

San Salvador San Salvador (; ) is the capital and the largest city of El Salvador and its eponymous department. It is the country's political, cultural, educational and financial center. The Metropolitan Area of San Salvador, which comprises the capital it ...

La Paz La Paz (), officially known as Nuestra Señora de La Paz (Spanish pronunciation: ), is the seat of government of the Plurinational State of Bolivia. With an estimated 816,044 residents as of 2020, La Paz is the third-most populous city in Bol ...

, and Cuscatlán departments. The caldera, which contains the second largest lake in the country and is immediately east of the capital city,

, has a scalloped to high rim. Any surplus drains via the

Jiboa River Jiboa River is a river of El Salvador. The river sources from Lake Ilopango Lake Ilopango is a crater lake which fills an 8 by 11 km (72 km2 or 28 sq mi) volcanic caldera in central El Salvador, on the borders of the San Salvador, L ...

to the Pacific Ocean. An eruption of the Ilopango volcano is considered a possible source for the

extreme weather events of 535–536 The volcanic winter of 536 was the most severe and protracted episode of climatic cooling in the Northern Hemisphere in the last 2,000 years. The volcanic winter was caused by an eruption, with several possible locations proposed in various contin ...

. The local military airbase,

Ilopango International Airport Ilopango International Airport is an airport located on the eastern part of the city of San Salvador, El Salvador, once serving the city as its international airport until it was replaced by the larger and more modern El Salvador International ...

, has annual airshows where international pilots from all over the world fly over San Salvador City and Ilopango lake.

Eruptive history

Four major

dacitic Dacite () is a volcanic rock formed by rapid solidification of lava that is high in silica and low in alkali metal oxides. It has a fine-grained (aphanitic) to porphyritic texture and is intermediate in composition between andesite and rhyol ...

–

rhyolitic Rhyolite ( ) is the most silica-rich of volcanic rocks. It is generally glassy or fine-grained (aphanitic) in texture, but may be porphyritic, containing larger mineral crystals ( phenocrysts) in an otherwise fine-grained groundmass. The ...

eruptions occurred during the late

Pleistocene The Pleistocene ( , often referred to as the ''Ice age'') is the geological Epoch (geology), epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fina ...

and

Holocene The Holocene ( ) is the current geological epoch. It began approximately 11,650 cal years Before Present (), after the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene togeth ...

, producing

pyroclastic flow A pyroclastic flow (also known as a pyroclastic density current or a pyroclastic cloud) is a fast-moving current of hot gas and volcanic matter (collectively known as tephra) that flows along the ground away from a volcano at average speeds of b ...

s and

tephra Tephra is fragmental material produced by a volcanic eruption regardless of composition, fragment size, or emplacement mechanism. Volcanologists also refer to airborne fragments as pyroclasts. Once clasts have fallen to the ground, they r ...

that blanketed much of the country. The caldera collapsed most recently sometime between 410 and 535 AD (based on radiocarbon dating of plant life directly related to the eruption), which produced widespread

s and devastated Mayan cities; however, a team of scientists concluded that the volcanic eruption might have happened in 431 AD ±2, based on volcanic shards taken from ice cores in

Greenland Greenland ( kl, Kalaallit Nunaat, ; da, Grønland, ) is an island country in North America that is part of the Kingdom of Denmark. It is located between the Arctic and Atlantic oceans, east of the Canadian Arctic Archipelago. Greenland ...

, levels of

sulphur Sulfur (or sulphur in British English) is a chemical element with the symbol S and atomic number 16. It is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms form cyclic octatomic molecules with a chemical formula ...

recorded in ice cores from

Antarctica Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean, it contains the geographic South Pole. Antarctica is the fifth-largest cont ...

, and radiocarbon dating of a charred tree found in volcanic ash deposits. The eruption produced about of

(several times as much as the 1980 eruption of Mount St. Helens), thus rating a 6 on the (VEI) Volcanic Explosivity Index. The "ash-cloud fallout ... blanketed an area of at least 10,000 square kilometers waist-deep in pumice and ash", which would have stopped all agricultural endeavor in the area for decades. It is also theorized that the eruption and subsequent weather events and agricultural failures directly led to the abandonment of

Teotihuacan Teotihuacan ( Spanish: ''Teotihuacán'') (; ) is an ancient Mesoamerican city located in a sub-valley of the Valley of Mexico, which is located in the State of Mexico, northeast of modern-day Mexico City. Teotihuacan is known today as ...

by the original inhabitants. Other researchers estimated that in its sixth-century eruption, Ilopango expelled the equivalent of of dense rock, making it one of the biggest volcanic events on Earth in the last 7,000 years.Greshko, M
Colossal volcano behind 'mystery' global cooling finally found
National Geographic. 23 August 2019. It was hypothesized that this eruption caused the

in Europe and Asia, but this is unlikely given the research published in 2020 that dates the eruption to 431 AD. Later eruptions formed several

lava dome In volcanology, a lava dome is a circular mound-shaped protrusion resulting from the slow extrusion of viscous lava from a volcano. Dome-building eruptions are common, particularly in convergent plate boundary settings. Around 6% of eruptions ...

s within the lake and near its shore. The only historical eruption, which occurred from December 31, 1879, up to March 26, 1880, produced a

and had a VEI of 3. The lava dome reached the surface of the lake, forming the

islet An islet is a very small, often unnamed island. Most definitions are not precise, but some suggest that an islet has little or no vegetation and cannot support human habitation. It may be made of rock, sand and/or hard coral; may be permanen ...

s known as Islas Quemadas.

References

External links

Global Volcanism Program: Ilopango

Lake Ilopango
at

NASA Earth Observatory NASA Earth Observatory is an online publishing outlet for NASA which was created in 1999. It is the principal source of satellite imagery and other scientific information pertaining to the climate and the environment which are being provided by NA ...

website {{DEFAULTSORT:Ilopango Lakes of El Salvador Volcanoes of El Salvador Calderas of Central America Volcanic crater lakes VEI-6 volcanoes VEI-7 volcanoes 1879 natural disasters 1880 natural disasters 1879 in El Salvador 1880 in El Salvador New islands

Eruptive history

See also

References

External links