A Year Of Darkness And Death

 

Samalas caldera and Segara Anak lake

Image credit:  Céline M. Vidal, Institut de Physique du Globe de Paris (IPGP)

The explosion lofted gigantic quantities of sulfate and ash into the atmosphere, which plunged the earth into a volcanic winter.

That something calamitous happened that year is clear in the chronicles. Friar Paris, living at the St. Albans Abbey in Hertfordshire, England, kept a journal, Historia Anglorum, describing “unendurable cold” that “bounded up the face of the earth, sorely afflicting the poor, suspending all cultivation, and killed the young of the cattle.” By June he reported nothing was growing and by fall there was nothing resembling a harvest. People began to die by the thousands, starting with the poor.

“…Dead bodies were found in all directions, swollen and livid, lying by fives and sixes,” he wrote. “When several corpses were found, large and spacious holes were dug in the cemeteries and a great many bodies were laid in them together.”

One of those “holes” apparently was Spitalfields cemetery in London, the largest gravesite ever recovered in modern times.

The Samalas caldera is adjacent to Mount Rinjani or Gunung Rinjani  an active volcano in Indonesia on the island of Lombok 

Archaeologists first thought that the bodies were victims of the plague, but later radiocarbon dating showed the bodies were interred in the middle of the 13th century, before the plague and right around the time of the eruption.

Some 18,000 people were buried at Spitalfields. While some were placed in orderly graves, many were jumbled together, indicating that the death rate vastly exceeded gravediggers’ ability to bury them properly.

But while the fact of the eruption had been linked to an historic event, no one knew which volcano was responsible.

“People knew the eruption was quite big, but until now no one had succeeded in finding it,” Lavigne said.

There were clues. The research started out with ice cores collected 30 years ago, which showed the ash from the eruption. The fact that ash was found both in Antarctica and near the Arctic indicated the explosion occurred in the tropics, Lavigne said.

They were looking for clues such as a caldera, the volcanic crater left by the eruption, and pumice, volcanic rock that pours or is blasted out of a volcano.

Indonesia has 130 volcanoes, few of them studied very well, Lavigne said, so it was tempting to place the blast there. So the scientists headed into the field and they found Samalas, matching exactly what they were looking for through geochemical testing.

Judging by the amount of sulfur found in the area, the explosion shot eight times as much sulfur dioxide into the air as the 1883 explosion of Krakatoa, which colored sunsets for years around the world, and 10 cubic miles of rock.

The column of dust and smoke probably reached 27 miles into the air; lava was found 15 miles away. The eruption was probably between May and October of the year before Friar Paris’ Annus horibilus.

The effects of volcanic eruptions on the climate are well documented, said volcanologist John Eichelberger, now dean of the graduate school at the University of Alaska Fairbanks but once head of the U.S. Geological Survey’s Alaska volcano research team.

Volcanoes put ash into the air, but “the big culprit is sulfur dioxide, which forms sulfuric acid droplets that are not reflective and don’t let as much solar radiation to the surface,” he said. “It doesn’t take much to disrupt the season and create a disaster.”

A drop of one or two degrees Celsius will shorten the length of a growing season, Eichelberger explained.

The volcano still is active, but Lavigne said that since the Samalas volcano erupted relatively recently — geologically speaking — it is unlikely to unleash another eruption as big any time soon.

Eichelberger was not so sure. If the 1258 eruption consisted of only a small part of the magma flowing beneath Samalas, the rest of it could go again at any time, so he is not sure it is safe.

“I wouldn’t bet my life on it,” he said.

The eruption is now thought to have started the Little Ice Age. 

The Little Ice Age (LIA) was a period of cooling that occurred after the Medieval Warm Period (Medieval Climate Optimum).  While it was not a true ice age, the term was introduced into the scientific literature by François E. Matthes in 1939. It has been conventionally defined as a period extending from the sixteenth to the nineteenth centuries,  or alternatively, from about 1350 to about 1850, though climatologists and historians working with local records no longer expect to agree on either the start or end dates of this period, which varied according to local conditions.

NASA defines the term as a cold period between AD 1550  and AD 1850  and notes three particularly cold intervals: one beginning about 1650, another about 1770, and the last in 1850, each separated by intervals of slight warming.  The Intergovernmental Panel on Climate Change Third Assessment Report considered the timing and areas affected by the LIA suggested largely independent regional climate changes, rather than a globally synchronous increased glaciation. At most there was modest cooling of the Northern Hemisphere during the period.

Samalas Caldera next to Mount Rinjani seen in September 2013 NASA satellite photo 

Polar ice core records attest to a colossal volcanic eruption that took place ca. A.D. 1257 or 1258, most probably in the tropics. Estimates based on sulfate deposition in these records suggest that it yielded the largest volcanic sulfur release to the stratosphere of the past 7,000 y. Tree rings, medieval chronicles, and computational models corroborate the expected worldwide atmospheric and climatic effects of this eruption. However, until now there has been no convincing candidate for the mid-13th century “mystery eruption.”

 

Drawing upon compelling evidence from stratigraphic and geomorphic data, physical volcanology, radiocarbon dating, tephra geochemistry, and chronicles, researchers argue the source of this long-sought eruption is the Samalas volcano, adjacent to Mount Rinjani on Lombok Island, Indonesia. At least 40 km3 (dense-rock equivalent) of tephra were deposited and the eruption column reached an altitude of up to 43 km. Three principal pumice fallout deposits mantle the region and thick pyroclastic flow deposits are found at the coast, 25 km from source. With an estimated magnitude of 7, this event ranks among the largest Holocene explosive eruptions.

 

Radiocarbon dates on charcoal are consistent with a mid-13th century eruption. In addition, glass geochemistry of the associated pumice deposits matches that of shards found in both Arctic and Antarctic ice cores, providing compelling evidence to link the prominent A.D. 1258/1259 ice core sulfate spike to Samalas. We further constrain the timing of the mystery eruption based on tephra dispersal and historical records, suggesting it occurred between May and October A.D. 1257.

 

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By Joel N. Shurkin, ISNS Contributor
Inside Science News Service