A representation of the Tembora eruption. (Click on image to enlarge)

Mount Tambora (or Tamboro) is an active stratovolcano,located on the island of Sumbawa, Indonesia.

The mount raised as high as 4,300 m (14,100 ft) before the eruption of 1815 , making it formerly one of the tallest peaks in the Indonesian archipelago. After a large magma chamber inside the mountain filled over the course of several decades, volcanic activity reached a historic climax in the super-colossal eruption of April 1815.

Ashfalls thickness following the eruption of Mount Tombora. (Click on image to enlarge).

Mount Tambora experienced several centuries of inactive dormancy before 1815.
In 1812, the caldera began to rumble and generated a dark cloud.

On 5 April 1815, a moderate-sized eruption occurred, followed by thunderous detonation sounds, heard in Makassar on Sulawesi (380 kilometres or 240 miles), Batavia (now Jakarta) on Java (1,260 km or 780 mi), and Ternate on the Molucca Islands (1,400 km or 870 mi).

On the morning of April 6, volcanic ash began to fall in East Java with faint detonation sounds lasting until 10 April. What was first thought to be sound of firing guns was heard on April 10 on Sumatra island (more than 2,600 km or 1,600 mi away).

At about 7 p.m. on 10 April, the eruptions intensified.[5] Three columns of flame rose up and merged. The whole mountain was turned into a flowing mass of "liquid fire". Pumice stones of up to 20 centimetres (7.9 in) in diameter started to rain down at approximately 8 p.m., followed by ash at around 9–10 p.m. Hot pyroclastic flows cascaded down the mountain to the sea on all sides of the peninsula, wiping out the village of Tambora. Loud explosions were heard until the next evening, 11 April. The ash veil had spread as far as West Java and South Sulawesi. A "nitrous" odour was noticeable in Batavia and heavy tephra-tinged rain fell, finally receding between 11 and 17 April.

A recent view of the Tombora caldera. (Click on image to enlarge)

The world largest eruption in recorded history

Tambora eruption killed an estimated 92 000 people and made of 1816 the year without a summer as the global climate effects were felt. Aerosols from the Tambora eruption blocked out sunlight and reduced global temperatures by 3 deg C. Europe missed a summer, and India had crop failures following the Tambora eruption. 100 cubic km of magma was erupted. Ten thousand people were killed immediately from the pyroclastic flows and the eventual toll due to starvation and disease may have been as high as 117,000. The eruption caused a tsunami with a wave height of 10 m.