Identified mystery volcano of late antiquity

Eruption in El Salvador stopped Mayan abuses and favored the plague in Europe

The caldera of Ilopango volcano is now filled by a large crater lake. About 1.500 years ago, his outbreak could have contributed to the climatic collapse in late antiquity. © NASA / GSFC / METI / ERSDAC / JAROS, US / Japan ASTER Science Team
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Dramatic consequences: About 1, 500 years ago, one of the strongest volcanic eruptions in history occurred in El Salvador. The eruption of the Ilopango caldera covered large parts of the Mayan empire with ashes and halted agriculture and buildings. At the same time, however, the volcano threw so many gases into the stratosphere that it cooled the climate in Europe and favored the ancient plague, the researchers report.

Researchers have suspected for some time that two major volcanic eruptions were decisively involved in the epidemic of the late antique plague. For from 536 the climate was unusually cold for several years, a haze swallowed parts of the sunlight. It came to bad harvests and famine, which favored epidemics. From ice cores, researchers conclude that the first eruption occurred in 536 in the northern hemisphere, the second around 540/41 in the tropics.

Volcano crater near San Salvador

Which volcano caused the second outbreak, now Robert Dull from the University of Texas in Austin and his team have found out. They investigated the eruption left by the Ilopango caldera in the immediate vicinity of the Salvadoran capital San Salvador. It has been known for some time that this volcano erupted during the classical period of Mayan civilization.

"However, neither the regional nor the global impact of this Tierra Blanca eruption in Central America has been studied so far, " the researchers explain. For their study, they have therefore dated and examined more than 80 outcrops, where ashes, tephra and lava flakes of the eruption then emerge.

Four times stronger than the Pinatubo outbreak

The result: Ilopango erupted in eight phases, the last and strongest of which took place in 539 or 540, exactly at the time when researchers set up the second major global eruption of global concern. "This points to the Tierra Blanca eruption as the climate-changing event identified in ice cores and located in the tropics, " Dull and his team say. display

But how intense was the Ilopango eruption? The researchers found that the volcanic eruption threw ash up to a distance of 100 kilometers and left a layer of volcanic deposits up to 70 meters thick in places. Dull and his team estimate that the eruption ejected a total of 43.6 cubic kilometers of lava and ash four times more than the 1991 Pinatubo eruption.

The important Mayan city of Tazumal was only about 80 kilometers from the Ilopango volcano. Mario Roberto Dur n Ortiz / CC-by-sa 3.0

Disaster for the Maya

"This volcanic eruption was one of the ten strongest of the last 7, 000 years, " say the scientists. The day- to week-long eruption series could have claimed more than 100, 000 casualties within a radius of 50 to 60 kilometers around the volcano. The thick layers of ash made entire tracts of land uninhabitable for years and brought the agriculture in this part of the Mayan empire largely to a standstill.

"This was a major natural disaster that had major consequences for the cultural development of the Maya, " says Dull. Because the nearby Guatemala was one of the centers of the Mayan civilization. Archaeological studies show that some Mayan cities were temporarily abandoned, construction stopped, and many Mayan trade routes were disrupted.

Worldwide cooling effect

But it was not only in Central America that the consequences of this eruption were perceptible. As the researchers discovered, the Ilopango eruption also threw between 9 and 90 megatonnes of sulfur gases up to 50 kilometers into the atmosphere. At this altitude, the resulting sulfur aerosols could be distributed almost all over the world and formed a haze that dampened solar radiation.

According to the researchers, it is very likely that the Ilopango outbreak was the eruption that contributed to the end of Sp? Tantike in Europe around 540. The results on age, eruption size and sulfur emission, as well as the volcanic location in the tropics, are strong evidence, according to Dull and his team. "It's another piece of the puzzle that helps us to understand the Eurasian history of this period, " they say. (Quaternary Science Reviews, 2019; doi: 10.1016 / j.quascirev.2019.07.037)

Source: EOS, Science

- Nadja Podbregar