Tambora and its pyroclastic flows

The eruption of volcanoes present multiple dangerous phenomena: lava, tsunamis, sulphuric acids. The effect of lava is mostly local, but tsunamis can travel across oceans and create havoc on distant coasts. The sulphuric acid can have an long-lasting effect on global weather patterns. A volcanic eruption may also be accompanied by another deadly symptom: a pyroclastic flow.

During the 79 AD eruption of Mount Vesuvius, the Roman cities of Pompeii and Herculaneum were covered by super-heated ashes that are part of volcanic pyroclastic flows. Pyroclastic flows consist of a fluidized mix of hot lava blocks, pumice, ash and expanding volcanic gasses. These flows race down volcanic slopes at very high speeds. Pyroclastic flows behave like fluids and move at phenomenal speeds, often at over 150 kilometers an hour. This deadly mixture moves so fast that it can even travel over long stretches open water.

The 1815 eruption of Tambora was the largest eruption in recorded history. About 175 cubic kilometers of ash were erupted. Ash fell as far as 1,300 km from the volcano. In central Java and Kalimantan, 900 km from the eruption, one centimeter of ash fell. The eruption column reached a height of about 44 km. The collapse of the eruption column produced numerous pyroclastic flows, destroying everything in their paths and boiling and hissing into the sea 25 miles away. Huge floating rafts of pumice trapped ships at harbor[1].

The pyroclastic flows extinguished the tiny kingdom of Tambora. After 20 years of research, the first remnants of a Tamboran village were discovered under a layer of ash three meters thick and has unearthed the first clues about its culture[2].

“There’s potential that Tambora could be the Pompeii of the East, and it could be of great cultural interest,” said lead-explorer Sigurdsson, who believes the village includes a large wooden palace that he hopes to find on future expeditions. “All the people, their houses and culture are still encapsulated there as they were in 1815.”

[1] Self et al: Volcanological study of the great Tambora eruption of 1815 in Geology - 2011
[1] University of Rhode Island: URI volcanologist discovers lost kingdom of Tambora: Indonesian civilization was wiped out by largest volcanic eruption in history – 2006. See here.