The eruption expelled a lake on its surface, throwing mud and pyroclastic flows from the heated water all over the surrounding agricultural areas and killing 5,000 people.
On May 1, 1919, the volcano Kelud, on the island of Java in Indonesia, erupted. It was its deadliest strike of the twentieth century. The eruption expelled the lake at the summit, approximately 5,000 feet above sea level. Mud and pyroclastic flows from the heated waters of the lake swept over the surrounding agricultural areas of Kediri and Blitar. They traveled as far as twenty-five miles from the volcano, destroying 40,000 acres of farmland. Three million people live within fifteen miles of the volcano and more than 5,000 people were killed on the day of the eruption. A hundred villages were destroyed. Kelud is a small volcano when compared with Indonesia’s others but, because of the lake at its summit and the frequency of its eruptions, it has been the source of many of Indonesia’s deadliest eruptions.
The 1919 eruption prompted the creation of the Volcano Survey of Indonesia with its first task being how to drain the lake waters from Kelud. There had been earlier attempts because of the known frequency of Kelud’s eruptions. In 1905, the local Dutch administration arranged for a dam to be built at the foot of the mountain in order to divert flows into the nearby river Badak. When the 1919 eruption occurred, this dam proved to be ineffective. It was taken away by the heavy mudflows that occurred. After this very destructive eruption, authorities decided to dig a tunnel and so prevent a repeat of the 1919 tragedy.
Extensive engineering work started in September 1919 and was finally completed in 1926. A tunnel, a thousand feet in length, had been excavated through the walls of the crater by that time. It lowered the elevation of the water by two hundred feet and thus reduced considerably the volume of water that remained. Unfortunately, successive eruptions in 1951 and 1966, though much weaker than the 1919 event, destroyed the drainage system that was in place and raised both the elevation and the volume of the summit lake. The reconstruction of the drainage system was initiated immediately after the 1966 event and it succeeded in limiting the volume of water in the lake to a manageable level.
Indonesia has a chain of 129 active volcanoes extending eastward for 4,000 miles from the northern end of Sumatra. Several eruptions of these volcanoes have been catastrophic in the past, as in the cases of Tambora in 1815 and Krakatau in 1883, both in terms of the loss of human life and the partial or total destruction of infrastructure and economy. Millions of Indonesians are currently living on volcanoes and civil infrastructures are progressively developing on their slopes. Due to the economic and demographic pressures that exist in Indonesia today, it is clearly not possible to prohibit settlement of population around these active volcanoes. The soil is incredibly good. One of the challenges for Indonesia is how to use and manage this land resource as well as to minimize the risk to humans and long-term economic effects of future eruptions.
The relatively inconspicuous 5,000-foot-high Kelud stratovolcano contains a lake in its crater at the summit that has been the source of some of Indonesia’s deadliest eruptions. More than thirty eruptions have been recorded from it over the past thousand years. In 1556 its mudflow from an eruption was responsible for 10,000 deaths. The ejection of water from its lake during Kelud’s typically short, but violent, eruptions creates pyroclastic and mud flows that lead to fatalities and destruction. These events have claimed more than 15,000 lives since 1500 and caused widespread destruction.
