An immense volcanic eruption in 1257 A.D. affected our entire planet. But which volcano exploded?

A massive volcanic eruption occurred in 1257 A.D. It produced enormous amounts of ash and sulfur and had a profound impact on the climate across the globe. It was the largest, if not the biggest eruption in the last 7,000 years. Evidence of this can be seen literally from pole to pole.
But... What volcano erupted?!

Strangely, no one knew which volcano had exploded until recent years. Geologists were left scratching their heads for years until they discovered multiple evidence that pointed to the actual smoking gun: the Samalas volcano, located on Lombok Island in Indonesia.

Ice cores from both the Arctic and Antarctic provide the strongest evidence for such a devastating eruption. Each year, a new layer of ice is placed in these areas. This traps gases and particulates in our atmosphere. These ice layers can be date extremely precisely, which makes them critical in determining the ages of global climate events.

Volcanic sulfate deposit spikes hard in ice deposits datable to 1257/1258 A.D. This indicates an eruption much larger than either Krakatau (1883) or Tambura (1815), which were eight- and twice as strong, respectively.

New evidence was gathered from radiocarbon dating, tree ring analysis, the geochemistry and volcanic deposits. Even an ancient historical record, called the Babad Lombok (written in Old Javanese on Palm Leaves) that records the explosion.

Zoom In Aerial View of Rinjani volcano, Lombok Island in Indonesia. This is the scene of a devastating eruption in 1257 A.D. Credit to Reinhard Dirscherl/ullstein Bild via Getty Images

Babad Lombok speaks of an eruption from a volcano named Samalas. It is now part a volcanic complex that also includes Mount Rinjani, which towers above 3,700m above sea level, and a large caldera that is partially filled in with water. This formed Segara Anak, a crater lake. The complex is still active and eruptions are still taking place. Gunung Barujari is a developing cone that has been growing since the mid-'90s, as well as through eruptive events.

Babad Lombok places the eruption in the middle to late 13th centuries, which is consistent with the ice-cores. The northern hemisphere was hit hard by a cold, unseasonable summer in 1258. Heavy rains and flooding caused widespread crop failures across Europe. This is also consistent with a massive eruption. Dark particles can rise into the stratosphere, blocking a fraction sunlight and lowering temperatures.

It is remarkable that tephra pieces of rock, and ash from volcanic eruptions that occurred around the same time were found in both the northern and the southern hemispheres. This suggests that the volcano was located near the Equator.

Zoom In. The Gunung Barujari volcanic is part of Rinjani, a relatively young cinder cone which grew quickly in the 1990s. Credit: Matthew Williams-Ellis/Education Images/Universal Images Group via Getty Images

If the Babad Lombok had indeed described the eruption, geologists turned to the Samalas caldera in search of evidence. Carbon-14, a radioactive form carbon that can accurately date events that affect living matter to 1257 A.D. was used to date the trunks and branches of burned trees. No young trees were found after this date which indicates that the eruption occurred in catastrophic conditions.

Fieldwork in the Samalas caldera, and the surrounding islands has revealed tephra deposits throughout the region. The chemistry of the glass shards found in the deposits matches that of the ice cores dating to the event. The scientists mapped the tephra deposits of the area and found that they accounted for 7.5 kilometers in volume as well as 7 billion tons fallout.

However, the volume of the eruption was far greater than that. Models of the preeruptive volcano show it rising to an elevation of approximately 4,200m above sea level (roughly 13,800ft), roughly equal to the height of Colorado's Rocky Mountain National Park's largest mountains. The peak was blown out of the sky during the eruption. Scientists have determined that 40 cubic kilometers of material was blown out during the eruption. The ash plume would have reached 43 km into the sky, with the possibility of reaching as high as 50km. It would have been visible hundreds of kilometers away.

Zoom In Rinjani volcano releases steam and ash in July 2013. This volcano is still active and was once part of the Samalas volcano. It exploded in 1257 A.D. Credit to Ulet Ifansasti/Getty Images

The event would have received a rating of 7.0 on Volcanic Explosivity Index. This logarithmic scale is used to rate volcanic explosions. For example, the 1980 Mount St. Helens eruption rates at a 5, and the last Yellowstone caldera eruption 600,000 years back was an 8. Therefore, the Samalas eruption was among the most significant in the last 12,000 years.

It was apocalyptic and must have terrified the population. The capital of the Lombok Kingdom, Pamatan (or Pamatan), was destroyed and is yet to be discovered. If it is ever found, it could resemble Pompeii. The steam explosions were caused by hot magma reacting to seawater (called phreatic explosions), and then there was a magmatic eruption that blasted rocks and pumice out to great distances (several hundreds of kilometers). Then came pyroclastic flow, hot ash and gases which can travel at hundreds of kilometers an hour and become scorching hot. Lombok Island's deposits reached 35m, which is the height of an 8-story building.

This is despite the fact that all evidence supporting this claim was scattered and indirect until a few decades ago. This research ties everything together, as well as the more recent climate change effects in northern hemisphere.

You might have heard some people claim that volcanic eruptions are responsible for a lot of carbon dioxide being released into the atmosphere, as I was able to see a tweet confirming this assertion. This is not only false, but also utterly incorrect. Human activities release more carbon dioxide than all the volcanoes in the world. A Samalas eruption would cool us down because of dark particulates. However, it would only do so for a short time and at a great, high cost.

Although powerful events such as the Samalas eruption could change the course and history of humanity, it can be difficult to pinpoint the scale of the planet's impact. Human activity has the potential to alter the planet, and it can be found all over the globe. Although I was shocked to learn about the destructive power of this ancient eruption it was also a reminder that we are actually doing worse and do so every day.

We have the option to choose, and this is unlike any other planet.