A multidisciplinary approach has made it possible to identify for the first time the exact date of the violent eruption which devastated the Central American region in the XNUMXth century AD
An international team of researchers, in which the National Institute of Geophysics and Volcanology (INGV) took part, identified in 431 AD, with a margin of uncertainty of about two years, the exact date of the eruption of the Ilopango volcanic caldera, called of Tierra Blanca Joven, in the Central American state of El Salvador.
The objective of the research was to date the eruption definitively, clarifying the impacts that this event had in the region, both on the climate and the environment and on human life, thus taking a further step forward compared to previous studies.
The violent eruption, which was known to have occurred in the period between 300 and 600, covered large areas of El Salvador with a thick layer of white ash and debris (partly still visible), including sites dating back to the so-called "classical period". ” of the ancient Mayan civilization, making an area within 80 km of the volcano uninhabitable for decades.
Furthermore, some archaeological evidence indicates that, around the date of 431 AD, El Salvador experienced a sudden interruption in the production of Mayan ceramics, an inactivity which was therefore compatible with the catastrophic natural event which struck the area.
Thanks to the multidisciplinary skills put in place by the group from 12 research institutes (including the University of Oxford and UNAM, the National Autonomous University of Mexico), the authors of the study 'The magnitude and impact of the 431 CE Tierra Blanca Joven eruption of Ilopango, El Salvador', just published in the scientific journal Proceedings of the National Academy of Sciences (USA), combined geological and archaeological data from Central America with chemical analyzes of ice cores from Greenland and Antarctica .
"To date past eruptive events for which there is no written information", explains Antonio Costa, Director of the Bologna Section of INGV and co-author of the study, "a method based mainly on the analysis of carbon decay is used -14 in the organic fragments incorporated by the eruptive mixture. Sometimes, as in this case, this method is not accurate enough because carbon-14 decay dating needs to be calibrated. The calibration data set is not well structured around the moment of the eruption and allows to identify a wide time span but not a precise date. The innovative and decisive aspect in this work, therefore, was undoubtedly the multidisciplinary approach which allowed us to cross-reference data from even very different disciplines to 'triangulate' the date we had been looking for for some time”.
In particular, it was thanks to fragments of volcanic glass found in ice cores taken in Greenland, dated 431 AD, that it was possible to identify a correspondence with the volcanic material emitted during the eruption of Tierra Blanca Joven and consequently date the eruption itself.
"This is a very important result", continues Costa, "because although we already had an estimate of the period in which this eruption had occurred, we were only able to unambiguously date the event with the results just obtained".
The eruption, according to the estimates made by the researchers, would have produced a column of gas and ash about 45 km high. Thanks to the comparison between the carbon-14 dating of the trunks of the trees felled by the force of the eruption and found in the residues of the pyroclastic flow and the chemical analyzes of the erupted products and of the fragments of volcanic glass present in the ice cores taken, it was possible identify a match that indicates the origin of the finds not only from the same time frame but from exactly the same eruptive event.
Furthermore, from a climatic point of view, the eruption would seem to have cooled the average temperature of the Earth by half a degree Celsius on a global scale, even if for a rather limited period of a few years; the most intense effects affected the same region of Central America where the event took place.
"What is important and interesting to underline", concludes Antonio Costa, "is how the results obtained with this work have implications not only for volcanology but also, for example, for climatology and archeology, resolving scientific questions that have remained until now unresolved".
LINK: https://www.pnas.org/content/early/2020/09/22/2003008117.short?rss=1
#ingv #pnas #tierrablancajoven #volcano #elsalvador #maya
El Salvador, the true date of the mysterious and colossal eruption of the Tierra Blanca Joven that shook the Maya civilization discovered
A multidisciplinary approach made it possible to identify for the first time the exact date of the violent eruption which in the 5th century AD. shocked the Central American region
An international team of researchers, in which the National Institute of Geophysics and Volcanology (INGV) took part, has identified that in 431 AD, with a margin of uncertainty of about two years, there was an eruption, known as of Tierra Blanca Joven, of the volcanic caldera Ilopango in the Central American State of El Salvador.
The aim of the research was to definitively date the eruption by clarifying the impacts that this event had in the region, both on the climate and the environment and on human life, thus taking a further step forward compared to previous studies.
The violent eruption, which was known to have occurred in the period between 300 and 600, covered with a thick layer of white ash and debris (partly still visible) large areas of El Salvador, including dating sites back to the so-called “classical period” ff the ancient Mayan civilization, making an area within 80 km from the volcano uninhabitable for decades.
Furthermore, some archaeological evidence indicates that, around the date of 431 AD, in El Salvador there was a sudden interruption of the production of Maya ceramics, therefore inactivity compatible with the catastrophic natural event that struck the area.
Thanks to multidisciplinary skills put in place by the group coming from 12 research Institutes (including the University of Oxford and UNAM, the National Autonomous University of Mexico), the authors of the study 'The magnitude and impact of the 431 CE Tierra Blanca Joven eruption of Ilopango, El Salvador', just published in the scientific journal Proceedings of the National Academy of Sciences (USA), combined geological and archaeological data from Central America with chemical analysis of ice cores from Greenland and Antarctica.
“To date past eruptive events for which there are no written records”, explains Antonio Costa, Director of the Bologna Section of the INGV and co-author of the study, “a method based on the analysis of carbon-14 decay in organic fragments englobed by the eruptive mixture is mainly used. Sometimes, as in this case, this method is not sufficiently accurate since the dating through the decay of carbon-14 must be calibrated. The calibration dataset does not have much structure around the time of the eruption, which provides a wide time span and not an exact date. The innovative and decisive aspect in this work, therefore, was undoubtedly the multidisciplinary approach that allowed us to cross data from disciplines that are also very different from each other to 'triangulate' the date we have been looking for for some time”.
In particular, it was thanks to the fragments of volcanic glass found in the ice cores taken in Greenland, dated 431 AD, that it was possible to identify a correspondence with the volcanic material emitted during the eruption of the Tierra Blanca Joven and consequently date the eruption itself.
“This is a very important result”, continues Costa, “because despite the fact that an estimate of the period in which this eruption occurred was already available, only with the results just obtained could we uniquely date the event”.
The eruption, according to the estimates made by the researchers, would have produced a column of gas and ash about 45 km high. Thanks to the comparison between the carbon-14 dating of the trunks of the trees felled by the force of the eruption and found in the residues of the pyroclastic flow and the chemical analysis of the erupted products and the fragments of volcanic glass present in the ice cores collected, it was possible to identify a correspondence that indicates the origin of the finds not only from the same time span but from exactly the same eruptive event.
Furthermore, from a climatic point of view, the eruption seems to have cooled the average temperature of the Earth by half a degree centigrade on a global scale, albeit for a rather limited period of a few years; the most intense effects mainly affected the region of Central America where the event took place.
“What is important and interesting to underline”, concludes Antonio Costa, “is how the results obtained with this work have implications not only for volcanology but also, for example, for climatology and archeology, resolving scientific questions that have remained so far unsolved” .
#ingv #pnas #tierrablancajoven #volcano #elsalvador #maya
Link: https://www.pnas.org/content/early/2020/09/22/2003008117.short?rss=1
Photo 1 - Ilopango volcano, responsible for the 431 AD Tierra Blanca Joven eruption (TBJ). The event produced an eruption of about 55 km3 of magma from this vent, modifying the structure of the volcanic caldera, now covered by a lake. Ph.: Prof. Gerardo J. Aguirre-Díaz, UNAM, Mexico
Photo 1 – Ilopango volcano, the source of the 431 CE Tierra Blanca Joven (TBJ) eruption. The enormous eruption erupted around 55 km3 of magma from this vent, which modified the collapse structure that is infilled by a lake. Ph.: Prof. Gerardo J. Aguirre-Díaz, UNAM, Mexico
Photo 2 - About 4 meters thick deposits of pyroclastic flows from Tierra Blanca Joven at a site located 30 km west of the volcano's crater. These very fast flows of gas and incandescent material covered and destroyed the surrounding area within a radius of 40 km. Ph.: Dr. Dario Pedrazzi
Photo 2 – Thick deposits (~4 m) of the Tierra Blanca Joven pyroclastic density currents at a site located 30 km west of the vent. These fast flows of hot particles and gas decimated everything within 40 km of the vent. Ph.: Dr. Dario Pedrazzi
Photo 3 - Islas Quemadas located in the middle of the Ilopango lake (the caldera that generated the eruptions) produced during the most recent eruptions of lava domes in 1880. Ph.: Dr. Antonio Costa
Photo 3 – Islas Quemadas located in the middle of Lake Ilopango (the caldera that generated the eruptions) produced during the most recent eruptions of lava domes in 1880. Ph.: Dr. Antonio Costa