Fifteen hundred years ago, Ilopango, a caldera volcano in what is now El Salvador, erupted in one of the largest such events in recorded history. Known as the Tierra Blanca Joven eruption, it sent 10.5 cubic miles worth of tephra (pumice and ash) into the air, more than 100 times the amount produced by the eruption of Mt. St. Helens of 1980. The settling solids blanketed the valley. below; those who did not are believed to have contributed to a cooler climate throughout the northern hemisphere.
The eruption has long been credited with hastening the end of the ancient Mayan civilization that flourished throughout Mexico and Central America. But a new study in the journal antiquity suggests that the eruption did not bode well for disaster, at least not for an area about 25 miles from the caldera. Instead, it enabled the rapid construction of a massive Mayan pyramid, a monumental structure that signaled the resilience of those who built it.
“Events such as eruptions and drought were often considered a major factor in ancient collapse, abandonment or decline,” says study author Akira Ichikawa, postdoctoral associate at the University of Colorado in Boulder. âMy research suggests that ancient people were more resilient, flexible and innovative. “
Ichikawa conducted excavations in San AndrÃ©s, a Mayan settlement in the ZapotitÃ¡n Valley near present-day San Salvador, the capital of El Salvador. There are the ruins of the Campana structure, an imposing pyramid that at the time would have eclipsed all the rest of the valley.
While digging several excavation trenches, the team uncovered eight layers of construction material. Eventually, they struck about 16 feet of pure white tephra that contained only a few shards of ceramic and other materials, suggesting that the builders had carefully sifted the ash and pumice stone before using it to build.
Construction began remarkably soon after the explosion decimated the valley. Radiocarbon dating indicates that construction may have started as soon as five years after the eruption. (Although estimates of the date of the disaster vary, Ichikawa says subsequent generations did not use tephra, suggesting that builders began construction while the eruption was still important in local memory.)
Builders may have chosen to use tephra because of its white color, says Kathryn Reese-Taylor, an archaeologist and professor at the University of Calgary who has studied community training in the Mayan culture. “[The colour] was probably of some importance, âsays Reese-Taylor, who was not involved in the study.
Veneration of volcanoes
Mesoamerican cultures considered volcanoes to be sacred, Ichikawa says. “Perhaps they believed that dedicating a monumental structure to the volcano was a logical and rational way to solve the problem of possible future eruptions.”
The Mayans weren’t the only people who worshiped volcanoes, says Mark Elson, associate professor of anthropology at the University of Arizona who studies the response of humans to volcanic reactions. He reports corn cob imprints found in black basalt near Sunset Crater volcano in Arizona, which erupted around 1085.
“We believe the corn was left as an offering in the lava flow by the Hopi in an attempt to control the volcano as best they could,” said Elson, who was not involved in the Maya study.