The Mount Tambora Eruption

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In 1815, one of the most catastrophic and deadly events in recorded human history occurred in Indonesia

A volcanic explosion took place which was larger than anything, any human had ever witnessed in over 10,000 years. 

The total global death toll from the event might have been as high as the tens of millions.

Learn more about the Mount Tambora explosion on this Episode of Everything Everywhere Daily.


Mount Tambora is located about 175 miles east of the island of Bali in Indonesia.

Prior to the 1815 explosion, it was one of the tallest mountains in Indonesia at approximately 4,300 meters or 14,100 feet high. 

For centuries prior, the mountain had been dormant. However, there is a big difference between a dormant volcano and an extinct volcano. It can be very difficult to tell the difference between the two as a dormant volcano can be inactive for thousands of years before coming back to life. 

The volcano on the island of Montserrat was considered to be extinct before erupting in 1995, and Fourpeaked Mountain in Alaska hadn’t been active for 10,000 years before it erupted in 2006. 

Geology was still in its infancy in 1815, so no one was prepared nor expected what was about to happen. 

What was happening is that deep below Mount Tambor a magma chamber had been slowing filling over centuries several miles below the surface. 

The magma chamber was emptied at some point in the past and slowly refilled. When the chamber filled, the pressure inside began to increase. 

The first signs that the volcano was coming to life occurred three years earlier in 1812. The volcano began to rumble and steam started to rise from the volcano. 

Things remained at this low level of activity for three years until April 5, 1815. 

On April 5, a giant explosion took place. 

The explosion was heard almost 1,000 miles away on various islands around the Indonesian archipelago. Many people thought that it sounded like the sound of gunfire This was just the start of what would be almost weeks of eruptions. 

On April 6, ash began falling on the eastern side of the isle of Java.

On April 10, the biggest eruption yet took place. Witnesses saw three giant plumes of lava that shot up from the volcano, and fiery lava began flowing out, covering the entire mountains. 

Pyroclastic flows of hot gas and volcanic matter came down the side of the mountain at over 100 miles per hour destroying the village of Tambora. It was like what buried the city of Pompeii, only hundreds of times greater. The heat of pyroclastic flows caused winds that were hurricane strength, which uprooted trees. 

A column of smoke and ash was sent 25 miles into the stratosphere. Pumice ejected from the volcano would float on the water, and was so thick that ships couldn’t leave port. 

Explosions continued until April 11th. 

Ash and pumice continued to be thrown into the sky for another six days. The major activity on the volcano didn’t cease until April 17th. Minor activity continued on Tambora through July. 

By any measure you choose to use, the Tambora explosion was the largest volcanic eruption in the last 10,000 years, and maybe even since the mega Mount Toba eruption 70,000 years ago, which is absolutely going to be a future episode. 

The eruption devastated the island of Sumbawa where it was located, as well as nearby islands such as Lombok. 

Sumbawa was covered in a meter and a half of volcanic ash. The forests and crops on the islands and many nearby islands were totally destroyed. 

The explosion on April 10th caused a tsunami that killed thousands on nearby islands. 

The 14,000-foot volcano had lost 4,000 feet of its height, being reduced to only 9,350 feet tall. 

To put the Tambor explosion in perspective, it was about 100 times bigger than the Mount Saint Helens explosion, and about 10 times bigger than the Krakatoa explosion 68 years later. 

On the Volcanic Explosivity Index, the Tambora eruption ranked a 7, which is the highest score ever recorded in human history. 

However, as great as all of the destruction was in the immediate area, it was nothing compared to the long-term effects from the volcano all around the world. 

As the ash was shot into the upper atmosphere, many of the larger particles fell out quickly. However, the finer particles and sulfur dioxide remained in the atmosphere for months, or even several years. 

All that particulate matter in the atmosphere was the cause of some spectacular sunsets as well as dropping the global temperature several degrees. 

1816 became known as the year without a summer as the world saw its coldest summer in centuries.

In Quebec City, they had a foot of snowfall in June. People took out their horse sleighs in New England and used them after June snowfalls. 

One Pharaoh Chesney, of Virginia, would later recall,  “On July 4, water froze in cisterns and snow fell again, with Independence Day celebrants moving inside churches where hearth fires warmed things a mite.”

Frosts were reported in Virginia on August 21 and 22. 

In India, it radically affected the monsoon schedule, which resulted in three failed harvests, and an outbreak of cholera, which spread through much of South and Central Asia. 

In China, crops died due to extremely late frosts, and a disrupted rain cycle. 

The global crop failures around the world lead to famine. The areas immediately near Tambora suffered famine almost immediately after the eruption as all the fields were destroyed, and there was no way to get them food, given the condition in the early 19th century. Their freshwater supplies were also contaminated by the volcano.

In Europe, the crop failures led to riots. It was the worst famine of the 19th century and the last great famine to occur in Europe. A typhus outbreak also occurred in many major cities around Europe. 

In Ireland, it led to an increase in rainfall which flooded the fields. It rained continuously in Ireland for eight weeks. 

In the United States, it led to failed crops and significant social changes. Farmers out east, dispirited by their crop failures, moved west.  All the population gains in the state of Vermont since their admission to the Union evaporated as people left to move west. 

The migration resulted in the creation of the state of Indiana in 1816.

It is difficult to pin down the exact impact of the Tambora Explosion because of the secondary and tertiary effects of the blast. Famine, social unrest, and pandemics on multiple continents can all be traced back to Tambora. 

The death toll has been estimated as high as a quarter-million people, but those estimates are only from the immediate impact of the explosion in the area around Indonesia. Once you factor in the other effects of the atmospheric ash in India, China, Europe, and North America, the death toll is probably in the tens of millions. 

Oddly enough, even though this is the biggest eruption in the last 10,000 years, at least, many people are unaware of it. They are far more familiar with other, smaller eruptions like Krakatoa or Pinatubo, mostly because those eruptions occurred in an era with electronic communication and photography. 

Tambora has mostly been forgotten, even though it was an order of magnitude larger than any other eruption in recent memory. 

The lesson of Tambora is that something that happens on an unknown island on one side of the world can have dramatic repercussions all over the Earth.