Indonesia contains not only the highest number of actively erupting volcanoes on the planet,
but also the highest number of volcanoes with deadly eruptions.
Many of its volcanoes have produced devastating eruptions such as Krakatoa in 1883, Mount
Tambora in 1815, Mount Samalas in 1257, and Mount Merapi in 1930.
Yet, there is another volcano which is just as deadly, which locals have largely forgotten
about.
The volcano I am referring to is Kelud, which has produced 7 deadly eruptions since record
keeping began in the 1500s.
So, why is this volcano so deadly?
This video will discuss this volcano, and mention what its future hazards are.
The Kelud stratovolcano is located within Indonesia, where it is on the south central
section of the island of Java.
Specifically, it is 35 kilometers west of the city of Malang.
From ground level, this volcano is not as prominent as several of its neighboring volcanoes,
such as Bromo and Semeru.
Compared to the aforementioned two volcanoes, it has a much older appearance, containing
dozens of deeply dissected valleys, which are consistent with much higher levels of
erosion.
However, this volcano in all likelihood is much younger, but has produced more frequent
large scale lahars and eruptions which are the cause of its deeply dissected valleys.
Thus, Kelud may be as young as 45,000 years old.
Regardless of when Kelud began forming, it originated when a significant volume of basaltic
andesite magma related to plate subduction to the south of the country reached the surface.
As this magma interacted with abundant groundwater in the region, it created a wide and deep
explosion crater during its first series of eruptions.
This large crater would later become the most recognizable part of the overall volcano.
Soon, continued eruptions deposited large volumes of ash and andesitic lava in a several
kilometer radius, building a distinctively gray volcano.
Occasionally, lava domes would form in its center, only to act as a pressure plug and
get destroyed via highly explosive plinian style eruptions, as was the case during its
deadly 2014 eruption.
Here is a before image of the summit crater, and here is it after the eruption.
It created widespread pyroclastic flows which flattened millions of trees and traveled up
to 7 kilometers from the main crater.
Although this eruption was rated on the volcanic explosivity index as a 4, it was far from
the deadliest eruption at this volcano.
Rather, the deadliest eruption occurred in 1586, which was an order of magnitude larger,
resulting in the deaths of 10,000 people.
These people were not largely killed by pyroclastic flows or falling ash, but rather a superheated
mudflow known as a lahar.
Lahars are the volcanic equivalent of flash floods, which often result in 100 meter high
walls of water with the viscosity of concrete.
Due to the great size and depth of Kelud's summit crater, it can theoretically hold more
than 200 million cubic meters of water.
When an explosive eruption occurs, this water is violently released downstream, creating
towering lahars.
Additionally, its mere presence intensifies the explosiveness of any already large eruption.
A similarly deadly eruption occurred in 1919, when 5,000 people as far away as 30 kilometers
were swept away by these mudflows.
However, since then eruptions have not been quite as deadly.
Following another destructive eruption in 1966, the government built a series of tunnels
called the Ampera Tunnels to drastically reduce the level of water present in the overall
volcano.
Although it has needed repair after every large eruption, its implementation has been
a huge success which saved countless lives.
Today, the maximum volume the crater lake can reach is only 2 million cubic meters of
water.
As for the 50,000 people who live within 10 kilometers of this volcano, I recommend living
away from any low points such as streams and rivers.
Both pyroclastic flows and lahars tend to seek out low points in overall topography.
I hope that you enjoyed this video!
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