When people think of a recent large volcanic eruption, several names come to mind. Taal,
Mount Saint Helens, Mount Pinatubo, and Krakatoa. However, there is another volcano
which erupted around 200 years ago which surpasses all of these other volcanoes in
size. I am referring to Mount Tambora, which produced the deadliest eruption in human
history. Its climate effects were profound, as it caused temperatures to decrease worldwide leading
to the aptly named "year without a summer". This video will discuss this volcano, its 1815
eruption, and mention what its future hazards are. Mount Tambora can be found in the south central
portion of Indonesia on the island of Sumbawa. Specifically,
it is 28 kilometers east of the city of Pekat. This volcano is truly massive. It is more than
60 kilometers wide, and makes up the entirety of the peninsula shown on screen. Mount Tambora
began forming around 190,000 years ago, when a series of effusive eruptions occurred. These
eruptions produced an abundance of fast moving basaltic lava, which moved quickly downslope.
This helped to form a wide shield volcano. Over the next 100,000 years, Mount Tambora continued to
produce rather non explosive eruptions similar to what is today witnessed on the Hawaiian Islands.
By 90,000 years ago, Mount Tambora was 4000 meters tall. Then, around 86,000 years ago,
the composition of the lava mysteriously changed. A massive eruption took place,
and formed a large caldera. Eruptions which grew out of this caldera produced lavas that
moved more slowly, and had more silica in them than the prior period of activity. As a result,
eruptions became more explosive. This change in composition marked the transition between
Mount Tambora being a shield volcano to its current classification as a stratovolcano.
Beginning around 80,000 years ago, intermittent eruptions outside of the volcano's center began.
Over the next 75000 years, these eruptions build 20 cinder cones. Mount Tambora then
became unusually quiet for several thousand years, in which only 3 small eruptions occurred.
One of these smaller eruptions occurred in 740 AD. The volcano
subsequently became dormant for 1000 years. Then, in 1812, the volcano came back to life.
A small eruption at the summit produced some black ash and a small eruption column. Over the
next 2 years, this small eruption continued, and the center of the mountain was uplifted.
At the time, Mount Tambora was the tallest volcano in all of Indonesia,
at an impressive 4300 meters in elevation. Then, on April 5th of 1815, residents up
to 1200 kilometers away were startled by a series of loud explosions which originated from Tambora.
Over the next several days, three distinguishable vents erupted and ejected lava and ash. On April
10th at 8 PM, these vents seemingly merged and produced what was described by locals as a "liquid
fire" which stretched into the atmosphere. Over the next 2 hours, twenty centimeters
of ash fell on towns within 30 kilometers of the mountain. Although it was night, the sky was lit
up due to the amount of lava and superheated rock being ejected into the atmosphere. Then,
at 10 PM, a violent wind blew down every tree in the vicinity. The residents fleeing the eruption
didn't know this at the time, but the 4300 meter tall mountain had just collapsed. A column of
ash shot 44 kilometers into the atmosphere. At the same time, pyroclastic flows more than a kilometer
high raced down the mountain in every direction. Some of these pyroclastic flows traveled more
than 40 kilometers, destroying everything in their path. When these flows and volcanic debris
reached the ocean, they generated a tsunami. Over the next several days, the eruption
continued at a violent intensity. Ash fell on areas more than 1000 kilometers away.
Once the ash cloud had cleared, people were shocked with what they saw. Mount Tambora
was now 1500 meters shorter. What used to be its peak was now a 6 kilometer wide crater.
Over the next year, the aftermath of this volcano's ash cloud wreaked havoc
across the world. The ash cloud partially blocked sunlight and caused crops to fail.
Global temperatures dropped, and in New York City, it snowed in June.
This deadly eruption was the largest to occur in recorded history, and was assigned
a volcanic explosivity index of 7. Since the formation of the caldera,
two small eruptions occurred. From 1847 to 1913, a small vent on the southwest caldera
floor intermittently erupted lava onto the surface. Again, in 1967, another eruption
occurred and erupted a small lava flow in the northeast of the crater. Although the volcano
has not erupted since, it still shows signs of unrest via earthquake swarms every few years.
These swarms indicate that future eruptions are likely. So, if you live nearby, should
you be worried? The answer is no. The vast majority of lava which could be erupted WAS
erupted during Tambora's colossal eruption. Future eruptions will likely be very small, and remain
isolated to within the caldera rim. I hope that you enjoyed this video.
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