April 10 1815: Mount Tambora Explodes

On April 10 1815, Tambora volcano, on the Indonesian island of Sumbawa, erupts.

The British governor of Java, Sir Thomas Stamford Bingley Raffles, the British governor of Java gives the following account of the eruption commencing from April 5 until the main eruption on April 10 1815. He writes

To preserve an authentic account of the violent and extraordinary eruption of the Tomboro Mountain on Sambawa, in April last, I required from the several Residents of districts on this Island a statement of the circumstances that occurred within their knowledge; and from their replies the following narrative is collected. It is, perhaps, incomplete until some further accounts are received of the immediate effects upon the mountain itself; but the progress is sufficiently known to render interesting a present account of the phenomenon, which exceeds any one of a similar description on record. The first explosions were heard on this Island in the evening of the 5th of April, they were noticed in every quarter, and continued at intervals until the following day. The noise was, in the first instance, almost universally attributed to distant cannon; so much so, that a detachment of troops were marched from Djocjocarta, in the expectation that a neighbouring post was attacked, and along the coast boats were in two instances dispatched in quest of a supposed ship in distress.

On the following morning, however, a slight fall of ashes removed all doubt as to the cause of the sound; and it is worthy of remark, that as the eruption continued, the sound appeared to be so close, that in each district it seemed near at hand; it was attributed to an eruption from the Marapi, the Gunung Kloot or the Gunung Bromo.

From the 6th, the sun became obscured; and it had every appearance of being enveloped in fog: the weather was sultry, and the atmosphere close and still: the sun seemed shorn of its rays, and the general stillness and pressure of the atmosphere foreboded an earthquake. This lasted several days, the explosions continued occasionally, but less violent, and less frequently than at first. Volcanic ashes also began to fall, but in small quantities; and so slightly as to be hardly perceptible in the western districts.

This appearance of the atmosphere remained with little variation, until the 10th of April, and till then it does not appear that the volcano attracted much observation, or was considered of greater importance than those which have occasionally burst forth in Java. But on the evening of the 10th the eruptions were heard more loud, and more frequent from Cheribon eastward; the air became darkened by the quantity of falling ashes, and in several situations, particularly at Solo and Rembang, many said that they felt a tremulous motion of the earth. It is universally remarked in the more eastern districts, that the explosions were tremendous, continuing frequently during the 11th, and of such violence as to shake the houses perceptibly; an unusual thick darkness was remarked all the following night, and the greater part of the next day. At Solo, on the 12th, at four p. M., objects were not visible at 300 yards distance. At Gresie, and other districts more eastward, it was dark as night the greater part of the 12th of April, and this saturated state of the atmosphere lessened as the cloud of ashes passed along and discharged itself on its way. Thus the ashes, which were eight inches deep at Banyuwangi, were but two in depth at Sumanap, and still less in Gresie; and the sun does not seem to have been actually obscured in any district westward of Samarang.

No description of mine, however, can so well express what happened, as the extracts from the reports at several places ; the remarks there made are applicable also to all the other districts, only in a lesser degree, as the same became more distant from the cause of the phenomena.

The Economist has a very fine article that describes the historical effects of this eruption, the largest in the last 500 years.

IF ALIENS had been watching the Earth during 1815 the chances are they would not have noticed the cannon fire of Waterloo, let alone the final decisions of the Congress of Vienna or the birth of Otto von Bismark. Such things loom larger in history books than they do in astronomical observations. What they might have noticed instead was that, as the year went on, the planet in their telescopes began to reflect a little more sunlight. And if their eyes or instruments had been sensitive to the infrared, as well as to visible light, the curious aliens would have noticed that as the planet brightened, its surface cooled.

Mount Tambora, a volcano on the Indonesian island of Sumbawa, was once similar in stature to Mont Blanc or Mount Rainier. But in April 1815 it blew its top off in spectacular fashion. On the 10th and 11th it sent molten rock more than 40 kilometres into the sky in the most powerful eruption of the past 500 years. The umbrella of ash spread out over a million square kilometres; in its shadow day was as night. Billions of tonnes of dust, gas, rock and ash scoured the mountain’s flanks in pyroclastic flows, hitting the surrounding sea hard enough to set off deadly tsunamis; the wave that hit eastern Java, 500km away, two hours later was still two metres high when it did so. The dying mountain’s roar was heard 2,000km away. Ships saw floating islands of pumice in the surrounding seas for years.

In his book “Eruptions that Shook the World”, Clive Oppenheimer, a volcanologist at Cambridge University, puts the number killed by the ash flows, the tsunamis and the starvation that followed them in Indonesia at 60,000-120,000. That alone would make Tambora’s eruption the deadliest on record. But the eruption did not restrict its impact to the areas pummelled by waves and smothered by ash.

The year after the eruption clothes froze to washing lines in the New England summer and glaciers surged down Alpine valleys at an alarming rate. Countless thousands starved in China’s Yunnan province and typhus spread across Europe. Grain was in such short supply in Britain that the Corn Laws were suspended and a poetic coterie succumbing to cabin fever on the shores of Lake Geneva dreamed up nightmares that would haunt the imagination for centuries to come. And no one knew that the common cause of all these things was a ruined mountain in a far-off sea.


Across Europe the summer of 1816 was cold and wet, and the harvest terrible. The effects were most notable around the Alps; in Saint Gallen, in Switzerland, the price of grain more than quadrupled between 1815 and 1817. Starving migrants took to the roads in their hundreds of thousands; mortality rates climbed due to starvation and disease. Death also stalked Yunnan, where Tambora’s cooling shut down the monsoon and cold days in summer killed the rice harvest for three years running.

Monsoons, which are driven by the difference in temperature between hot land and cooler sea, are particularly vulnerable to the excessive cooling of the land that volcanoes bring. Their weakening can have effects on more than crops. In his excellent account of the global impacts of the 1815 eruption, “Tambora”, Gillen D’Arcy Wood of the University of Illinois draws on the writings of James Jameson, a doctor in Calcutta, who held the lack of fresh water which followed the failure of the 1816 monsoon responsible for the cholera epidemic that swept through Bengal the following year.


In America, the spike in grain prices caused by Europe’s hunger drove a wave of farmers across the Appalachians to where the Ohio Valley was enjoying far more clement weather, with barges taking exports for Europe down the Mississippi in ever larger amounts. The collapse in the grain price when Europe’s harvest recovered contributed to the American economy’s first major depression.

The historian John Post, in a study of Tambora’s effects published in 1977, “The Last Great Subsistence Crisis in the Western World”, held that the volcano reshaped European politics. The disorder that sprang up in the bad weather from 1816 to 1818, and its subsequent repression, created a climate for authoritarian rule that held sway until the middle of the century. Mr D’Arcy Wood points out that it was in the aftermath of the Tambora famines that farmers in Yunnan started to plant opium poppies, the value of which as a cash crop offered some insurance against future failures of the grain harvest.

On top of such structural shifts, there are the personal stories. If Shelley, Byron and their romantic entourage had not been cooped up in a Swiss villa by incessant rain, would they have amused themselves by writing horror stories for each other—including John Polidori’s “The Vampyre”, the first novel to deal with seductive bloodsucking aristocrats, and Mary Shelley’s “Frankenstein”, which has shaped fears of scientific innovation from that day to this? If the summer frosts of “Eighteen-hundred-and-froze-to-death” had not driven Joseph Smith, a farmer, from Norwich, Vermont to Palmyra, New York, a place of vigorous religious enthusiasms, would his son Joseph junior still have been able to find the golden tablets to which the angel Moroni led him a few years later, or would the history of Mormonism have been very different?

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