July 15, 2024

The 1257 Samalas Eruption

In 1257 the Samalas Eruption blew apart a volcano in Indonesia. The effects were felt all over the world.

Map of Lombok
Map of Lombok

Lombok is an island in the West Nusa Tenggara province of Indonesia, in the central part of the country. It looks a bit like a teardrop, with a tail.

To the west is Bali, Indonesia’s most popular tourist destination. The two islands are separated by a narrow sea, and share similar climates and ecosystems.

Lombok is a small island, dominated by one geographic feature: in its centre is a massive volcano.

The Samalas Eruption: Gunan Rinjani, and the remnant of Gunan Samalas
Gunan Rinjani, and the remnant of Gunan Samalas

Known as the ‘Samalas-Rinjani Volcanic Complex’, Lombok’s big volcano is actually two different mountains: Gunan Rinjani, and Gunan Samalas.

That is, there used to be two different mountains.

In the 13th century, Gunan Samalas was destroyed in a cataclysmic volcanic eruption. Only a stub remains; a small volcanic smoker, percolating in the crater left by this disaster.

The Samalas Eruption is likely the largest in the Holocene era. This geologic time period stretches back about 13 000 years to the end of the last ice age, and contains all of modern human civilisation.

The event was only studied in detail within the last 10 years. But its impact had been known for some time, recorded in evidence around the globe.

The Earth's layers
The Earth’s layers

The planet Earth is structured in layers.

At the centre is a core of iron, part solid and part liquid. Rapidly spinning and highly magnetic, this provides the planet’s magnetic field, which shields us from the solar wind and creates the auroras near both poles.

On the surface is a layer of solid rock, called the crust. This is only about 10 kilometres thick; if the earth were the size of a basketball, the crust would be like a stamp, stuck to it.

This is the stable part of the planet, where we all live.

Between these two is a vast expanse called the Mantle. The Mantle consists of rock in a state between the liquid core and the hard surface; a soupy, very hot substance called Magma.

When volcanos erupt, they release large quantities of gas and rock into the atmosphere, mostly from the Mantle. When they spew lava, this is Magma brought to the surface.

Volcanic materials have a distinctive composition. One of their primary traces is sulphur, which is more common in Magma than in the Earth’s crust.

Ice cores from Antarctica
Ice cores from Antarctica

Scientists study ice cores from frozen areas of the planet, to help them determine how climate has changed over long periods of time. Ice traps atmospheric gases within it, that can be extracted.

Through the 1980s and 90s, these studies revealed something unusual. Ice samples taken from Antarctica and Greenland both showed a sudden increase in the level of atmospheric sulphur, from around 700 years previously.

The results were confirmed through studies of long lived trees, and sedimentary layers in African lakes. Both record traces of the environment, and both showed the same increase in sulphur.

Using carbon dating, scientists were able to pinpoint the sulphur spike with remarkable precision. In 1257 CE, the Earth’s atmosphere had received a dramatic influx of sulphur gas.

The most likely cause was a large volcanic eruption. But which volcano, and where?

Quilotoa, Ecuador
Quilotoa, Ecuador

Scientists narrowed the search to several possible volcanic culprits. Among them, Okataina in New Zealand, El Chichón in Mexico, and Quilotoa in Ecuador.

While broadly similar, material ejected from volcanos does have a unique signature, reflecting the geology of the area they are in.
Analysing long ego eruptions is painstaking work. The preserved ash is miniscule in volume, and the samples are fragile.

As the research continued, a new candidate emerged: Gunan Samalas, in Indonesia. The mineral composition of this area matched the material from the ice cores, and a large eruption had taken place around the right time.

In 2013, a team at the Pantheon-Sorbonne University in Paris wrote a paper that compiled the evidence.

‘Combining historical data, geochemistry, carbon dating, and physical evidence to arrive at the conclusion, their case for Samalas is compelling.’

– Erik Klemetti, geoscientist and volcano blogger

Amazingly, a first had account of the eruption was discovered as well.

Traditional Sasak House, Lombok
Traditional Sasak House, Lombok

European exploration of Lombok began in the 1500s. Little is known of life on the island before this time.

The native population is the ‘Sasak’ people. Their traditional lifestyle was agrarian, bolstered by fishing and sea trade.

One of their distinctive cultural traits were their houses, which were built on stilts, with a kind of horseshoe shaped dome. The unusual design was to help mitigate the effects of earthquakes, which were common.

The Sasaks were organised into tribes, ruled over by a King. The different tribes were frequently in conflict with each, and the tribes of nearby Bali; control of the throne changed regularly.

The seat of power was the Imperial city of Pamatan.

The Sasaks spoke Old Javanese and recorded key events on palm leaves, some of which have been preserved. Among these is the ‘Babad Lombok’, which describes the Samalas Eruption.

Based on oral accounts from survivors, the story it tells is one of apocalyptic devastation.

Preserved palm leaf writing
Preserved palm leaf writing

In the lead up to the Samalas Eruption there would have been earthquakes, and ominous smoke from the mountain’s summit. There may also have been smaller eruptions, as a precursor.

When the mountain finally blew, it was spectacular, and terrifying.

The entire top part of the peak was consumed in one titanic explosion. The Babad Lombok describes a massive cavity left in the aftermath; scientists estimate 100 cubic metres of rock were expelled, causing a smoke plume that stretched 40km into the atmosphere.

Debris rained down on the surrounding countryside, followed by rivers of lava. People fled in terror, abandoning villages that were then consumed. Pamatan, and the smaller city of Lae, were both swallowed up; no trace of either has ever been found.

The lava flows were only stopped when they reached the ocean, 20 kilometres away.

Today, when you go swimming on the west coast of Lombok, you will find the ocean floor rocky, instead of sandy; this is cooled lava, from the Samalas Eruption.

Other impacts were felt even wider.

Early historian, Matthew Paris
Early historian, Matthew Paris

In England, the winter of 1257-58 was particularly cold and harsh. The summer was even worse.

‘Such unendurable cold bound up the face of the earth, suspended all cultivation, and killed the young of the cattle.

Scarcely were there visible any small plants, or any shooting buds of flowers. In consequence, but small hopes were entertained of the fruit crops.

Owing to the scarcity of wheat, a very large number of poor people died; and dead bodies were found in all directions, swollen and livid.’

– Matthew Paris, 1258

Paris was a Benedictine monk in St Albans, Hertfordshire, whose writing and drawings provides a snapshot of life in this era. They also give an account of an extreme weather event; throughout the year, temperatures were much lower than usual, and rainfall higher.

Similar conditions were experienced across Europe. This lead to crop failure, famine, and many deaths from starvation.

St Mary Spital
St Mary Spital

In 1991, an archaeological excavation at Spitalfields Market, in East London, uncovered a remarkable find: thousands of skeletons buried in mass graves.

In medieval times, the site had been the location of a priory and a hospital, known as St Mary Spital. The burial pits were initially thought to be for victims of the bubonic plague; the ‘Black Death’ that ravaged Europe in the 14th century.

But examination of the skeletons revealed no genetic traces of the plague. Carbon dating also placed them around 1250 CE, about 100 years before the disease peaked in Europe.

If they weren’t plague pits, what were they?

Spitalfield mass grave
Spitalfield mass grave

The mystery persisted until the 2010s. Then, a member of the team working on the Spitalfields site, osteologist Don Walker, stumbled across the new research on the Samalas Eruption.

‘That was the eureka moment. What is new is linking the cause of the deaths of so many thousands to this volcano.


This global event, one of the largest volcanic eruptions of the last 10,000 years, and certainly the largest of the millennium, was causing the problems.’


– Don Walker

The Samalas Eruption had released so much material into the atmosphere it had impacted the global climate, causing dramatically colder and wetter weather in Europe, thousands of kilometres away.

Other mass burial pits have been found across the continent, that may be linked to the same eruption.

Artist's depiction of the Little Ice Age, London
Artist’s depiction of the Little Ice Age, London

Between 1300 and 1850 the world’s climate cooled significantly, a period dubbed ‘The Little Ice Age’.

Mean annual temperatures in the Northern Hemisphere declined by 0.6 degrees Celsius, alongside higher rainfall and the expansion of glaciers. Significant amounts of cultivated land were buried under ice and snow; combined with the colder weather, this lead to crop shortages and famine.

The cause of the Little Ice Age is still not fully understood. But one of the leading theories is an increase in volcanic activity, having a longer term impact on climate.

While the Samalas Eruption was not large enough on its own to cause such a dramatic change, it may have been the trigger. Other eruptions in the 13th and 14th centuries could then have contributed to the colder weather spiral.

Volcanos are awe inspiring; their power difficult to comprehend. And their ability to impact human civilisation, close to unparalleled.

Anak Krakatoa: the volcanic remnant of the Krakatoa eruption
Anak Krakatoa: the volcanic remnant of the Krakatoa eruption

In August 1883, in a different part of the Indonesian archipelago, the volcanic island Krakatoa exploded in a fierce eruption.

The sky turned black as night, as house sized chunks of pumice fell on the surrounding islands. A huge tidal was created as the mountain was obliterated, and explosions so loud they were heard 3 000 kilometres away in Perth, Western Australia.

Brilliant red sunsets were seen all around the world in the aftermath, and the following winter was significantly colder. Crops failure and famine were again experienced.

36 000 people were killed directly in the disaster, likely the most famous eruption in history.

So it is sobering to note: the Samalas Eruption is estimated to have been 8 times larger than Krakatoa.

The Samalas Eruption: still smouldering
The Samalas Eruption: still smouldering

The remainder of Samalas, the little crater lake smoker, has erupted 15 times since 1900.

In 2018, 1 000 trekkers and guides had to be evacuated when category 7 earthquakes shook the mountain. Its volcanic activity is monitored constantly.

The remains of Samalas continue to grow, slowly, every year.


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