In the evening of 5 April 1815 the lieutenant-governor of Java, Sir Stamford Raffles, instructed two boats in Batavia (the present Djakarta) to go to the Javasea because incredible explosions were heard (they thought there was a ship in danger).
Later it would come clear that it was the 2850m high Tambora composite volcano, which was erupting
from the 10th of April 1815, that caused the loud noise.
(Fig. 2.30) Credit: Nasa
An image of Tambora volcano from above, the volcano is located in the middle of the picture.
In total 10,000 people on Soembawa and the islands around it had been killed, after which 82,000 people would die from starvation and diseases (a cholera epidemic broke out).
A big part of Soembawa was covered with a 1.5m ashlayer, the sea around the island was strew with dead trees and big pumice stones (a light, brittle and spongy volcanian stone which can absorb a very big amount of gas through which it can float) were floating around.
A week later when the heavy eruptions had come to an end, the Tambora was not 4,500 metres tall anymore, but only 2,850 metres!
The Tambora was burning and rumbling for 3 months before there came a state of rest. The hardest explosions were audible until a distance of 1500 kilometres and a surface of approximately 500000m2 had been covered with ash. However, the most extensive effect was that people around the world
noticed something strange about the climate.
Geologists (of our time) have calculated that the Tambora has spit around 1,700,000 tons of debrea into the air. Most of the debrice fell down again in the neighbourhood of Soembawa. The rest of the debrice was pulverized to a talcous dust which was so light it was hanging in the atmosphere. The dust was carried high into the stratosphere where it began to float around the earth. Due to this immense cloud of dust a part of the incoming sunlight was bounced back into space, through which the earth was given less sunlight. The dust also worked
like a big filter which caused beautiful orange sunsets.
Although nobody was in the opportunity to study the eruption of Tambora from close, the reports on the intensity of the eruption and the surface on which ash has fallen provided an addition to the view people had on volcanology these days.
As late as 1847, 30 years after the eruption, the first pure scientific expedition, with the Swiss researcher Zollinger as the captain, went on his way
with the goal to study the Tambora.