Mount Tambora is an active stratovolcano on the Sanggar peninsula of northern Sumbawa, in Indonesia’s West Nusa Tenggara province, between the Flores Sea and Saleh Bay. Its eruption of April 1815 was the largest in recorded history: rated 7 on the Volcanic Explosivity Index, it threw out as much as 150 km³ of material, cut the mountain from roughly 4,300 m to under 2,900 m (the Global Volcanism Program now gives 2,722 m), and left a caldera 6 to 7 km across. At least 71,000 people died, most of them on Sumbawa and neighbouring Lombok from the famine and disease that followed, and the sulfur it injected into the stratosphere cooled the globe enough that 1816 became the “Year Without a Summer”, with failed harvests from New England to Ireland and Yunnan. Today the slopes are again farmed and settled, by villages such as Sanggar, Calabai and Doro Peti, around a national park created in 2015.
Sumbawa’s Sanggar Peninsula Before April 1815
Tambora is a product of the Sunda Arc, the line of volcanoes formed where the Australian Plate sinks beneath the Sunda Plate at about 7.8 cm a year. The volcano sits about 340 km north of the Java Trench, roughly 180 to 190 km above the descending slab, and its activity began somewhere between 57,000 and 43,000 years ago. Its growth drained a large magma chamber, and Saleh Bay first appeared as a sea basin about 25,000 years ago. By the early 19th century it stood as a single cone with a base some 60 km wide and a summit of about 4,300 m, among the highest peaks in the archipelago, and had been quiet for centuries while its chamber refilled.
Sumbawa, an island of 15,448 km², was known across the East Indies for honey, horses, sappanwood for red dye and sandalwood for incense and medicine, and its dry, savanna-like grasslands still carry horses, cattle and deer. The eastern and central island was divided among four sultanates, including Sumbawa, Dompu and Bima, with ties to the Bugis and Makassar peoples of South Sulawesi; Islam reached the island through the Makassarese, and many villages had converted by the 17th century. On the Sanggar peninsula itself lived a people whose language was unlike any around them. A short word list collected before the eruption, published by Stamford Raffles in 1817, shows that Tambora was not an Austronesian language; linguists treat it either as the westernmost Papuan language or as an isolate. The island’s two larger groups were, and still are, the Sumbawa people of the west, whose language resembles Lombok’s Sasak, and the Bima people of the east.
In 2004 a team led by Haraldur Sigurðsson, with the University of Rhode Island, the University of North Carolina Wilmington and Indonesia’s Directorate of Volcanology, dug about 25 km west of the caldera and 5 km from the shore. Under 3 m of pumice and ash they found a house holding the remains of two adults, with bronze bowls, ceramic pots, iron tools and finely decorated china, possibly from Vietnam or Cambodia. The objects suggest well-off traders on a productive farming coast; Sigurðsson called the site the “Pompeii of the East”.
10–11 April 1815: Tambora Village, Sanggar and the Famine That Followed
The eruption, hour by hour
The mountain began to rumble in 1812. On 5 April 1815 a large eruption produced detonations heard in Makassar, 380 km away, in Batavia (now Jakarta), 1,260 km away, and in Ternate in the Moluccas, 1,400 km away. Ash began falling on East Java the next morning. At about 7 pm on 10 April the eruption intensified: three plumes rose and merged, pumice up to 20 cm across fell from about 8 pm, and ash followed. A violent whirlwind flattened nearly every house in the village of Sanggar. Then the eruption column collapsed, and pyroclastic flows poured down every side of the peninsula to the sea, destroying the village of Tambora and affecting about 874 km² of land. The explosions, which people on Sumatra more than 2,600 km away first took for gunfire, continued until the evening of 11 April.
The sea brought its own damage. A tsunami about 4 m high struck Sanggar at around 10 pm on 10 April, with waves of 1 to 2 m at Besuki in East Java and about 2 m in the Moluccas; tsunami deaths are put at around 4,600. Uprooted trees mixed with pumice formed rafts up to 5 km across, and one was sighted in the Indian Ocean near Calcutta in early October. For up to two days, darkness covered places as far as 600 km from the summit, and ash fell at least 1,300 km away. When the explosions ended on 15 July, the summit had lost about 1,450 m of height, and the whole island’s vegetation had been destroyed.
Counting the dead on Sumbawa and Lombok
The eruption killed far more people after it ended than during it. With fields buried and livestock dead, starvation and disease spread across Sumbawa and to Lombok. The Swiss botanist Heinrich Zollinger, who spent several months on Sumbawa in 1847 collecting accounts from survivors, put the direct deaths at about 10,000, mostly from pyroclastic flows, with many thousands more starving on Sumbawa and about 10,000 dying of hunger and disease on Lombok. Later estimates have ranged widely, depending on which sources each author trusted.
W. A. Petroeschevsky estimated in 1949 that about 48,000 people died on Sumbawa and 44,000 on Lombok, and Stothers used a total of 88,000 in 1984. In 1998 Tanguy and colleagues argued those figures rested on untraceable sources and rebuilt the count from Zollinger and the notes of Stamford Raffles, who governed the British-held Dutch East Indies at the time: about 11,000 deaths from the eruption itself and 49,000 from famine and epidemics, with more victims likely on Bali and East Java. Clive Oppenheimer’s 2003 estimate of at least 71,000 is the figure most often quoted. The Tambora people and their language did not survive, and after 1815 the kingdoms based at Sumbawa Besar and Bima became the island’s two centres, a division that persists in its culture today.
1816 Far From Sumbawa: Frost in Connecticut, Famine in Ireland and Yunnan
The eruption column reached more than 43 km into the stratosphere and released an estimated 10 to 120 million tonnes of sulfur, which formed a veil of sulfate aerosol around the globe. Through the summer and autumn of 1815 Londoners saw long, brilliantly coloured sunsets, and in 1816 a persistent “dry fog” dimmed the sun over the north-eastern United States. Average global temperatures fell by about 0.4 to 0.7 °C, and 1816 became the second-coldest year in the Northern Hemisphere since 1400.
For farmers, that drop was enough. Frost hit Connecticut on 4 June 1816, snow fell in Albany, New York, on 6 June, and near Quebec City snow kept falling until 10 June, reaching 30 cm. Crops failed across North America, and thousands of families left New England for western New York and the territories beyond; Indiana became a state that December. In Europe, still recovering from the Napoleonic Wars, wheat, oat and potato harvests failed in Ireland and Britain, families from Wales walked long distances begging for food, and grain riots broke out in German and other European cities; it was the worst famine of the century. Typhus epidemics between 1816 and 1819 killed more than 65,000 people as the disease spread out of Ireland. In Asia, a disrupted monsoon brought floods to the Yangtze valley and famine to Yunnan, while delayed rains in India helped a new strain of cholera spread out of Bengal in 1816. The cold, wet June at Villa Diodati on Lake Geneva, where Mary Shelley began Frankenstein, belongs to the same story.
Pekat Coffee, Doro Peti and Tambora National Park: Living on the Slopes Today
Sumbawa took decades to recover. When Zollinger climbed the mountain in 1847, his feet broke through a crust into warm, powdery sulfur, though trees were already returning on the lower slopes. Organised resettlement began in 1907, and in the 1930s a coffee plantation was established at Pekat on the north-western slope, continuing a Dutch-era crop that had given its name to Tambora coffee. A dense rainforest of Duabanga moluccana trees, covering up to 80,000 hectares between about 1,000 and 2,800 m, grew back on the mountain and was described by a Dutch team led by Koster and de Voogd in 1933.
That forest became a resource in its own right. A commercial logging company has held a timber concession of 20,000 hectares, about a quarter of the forest, since 1972; another part is a hunting ground, and a wildlife reserve between them shelters deer, water buffalo, wild pigs and flying foxes. Trapping for the cagebird trade has pushed the yellow-crested cockatoo close to extinction on Sumbawa, and orange-footed scrubfowl are hunted for food. In 2015, the bicentenary of the eruption, the conservation area protecting the mountain was upgraded to a national park.
The people closest to the caldera live in three clusters: Sanggar to the east, Doro Peti and Pesanggrahan to the north-west, and Calabai to the west. Bima and Dompu are the nearest cities. Hikers reach the rim either from Doro Mboha on the south-east, along a paved road through a cashew plantation to 1,150 m, or on foot from Pancasila village at 740 m on the north-west, a 16 km climb of about 14 hours. Work on the island is scarce and droughts are frequent, so many people leave: some 500,000 workers from West Nusa Tenggara, more than 10% of the province, have gone abroad, many to the Middle East as labourers or domestic workers.
The mountain is still active. Small lava domes and flows have appeared on the caldera floor since 1815, the last recorded eruption was a gentle, non-explosive one in 1967, and in August 2011, the year a very small eruption was also reported, the alert level was raised after earthquakes and steam emissions in the caldera. Indonesia’s volcano agency watches it from a post at Doro Peti. Its hazard map bans settlement in a 58.7 km² danger zone around the caldera and marks a 185 km² zone of caution covering Pasanggrahan, Doro Peti, Rao, Labuan Kenanga, Gubu Ponda, Kawindana Toi and Hoddo, along with the Guwu river. With Indonesia’s population at 270 million in 2020, an eruption on the scale of 1815 would affect an estimated eight million people. For a later Indonesian eruption that also darkened skies worldwide, see our guide to Krakatoa; how cones like Tambora’s are built is covered in what is a stratovolcano, and the hole it left ranks among the largest calderas in the world.