Indonesia's Mountains of Fury
Figure 1: The Anak Krakatau volcano, infamous for its extreme eruptions is seen here launching lava bombs and generating its own lightning during its eruption on October 25, 2018.
Indonesia is a volcanically active country, and is home to numerous major volcanoes. It has the most volcanoes of any country in the world, with 76 volcanoes that have erupted at least 1,171 times in total within historical times. The Smithsonian Institution has 141 entries in its volcano database. Indonesia has around 130 active volcanoes that are part of the Pacific Ring of Fire, and it has suffered the highest numbers of eruptions resulting in fatalities, damage to arable land, debris flows, tsunamis, lava domes, and pyroclastic flows. Indonesia's most active volcanoes are Kelut and Mount Merapi on the island of Java. The majority of Indonesia's volcano are located on a 5,000 km long chain called the Sunda Arc. Here, the heavy oceanic Indo-Australian Plate subducts beneath the continental Eurasian Plate creating most of these volcanoes.
Figure 2: Map of Volcanoes in Indonesia
Indonesia's Deadliest and Most Active Volcanoes
Mount Merapi
Mount Merapi is a volcanic peak located near the center of the island of Java in Indonesia. Merapi, which means "Mountain of Fire", rises to 2,911 meters and has steep slopes with dense vegetation on its lower flanks.
It is the most restive of Indonesia's 130 active volcanoes. One of its largest eruptions occurred in 1006 and spread ash throughout Central Java. Other major eruptions were those of 1786, 1822, 1872, 1930, and 1976. Almost half of Merapi's eruptions have been accompanied by pyroclastic flows, which are clouds of superheated gases and incandescent solid particles. In the eruption of November 22, 1994, the release of a pyroclastic flow killed 64 people. A series of eruptions of the volcano in late 2010, which included pyroclastic flows, killed scores of people, injured dozens more, and forced tens of thousands to evacuate the area.
Mount Kelud
Figure 4: Lava streams from the new dome of Kelud on November 28, 2007
More than 30 eruptions of Kelud have been documented since 1000 AD. During a strong eruption in 1586, more than 10,000 people were killed. In 1919, more than 5,000 people died during an eruption. After this devastating event, the term lahar which means volcanic mud flow, was introduced as an internationally used technical term. In 1990, the volcano then spewed lava and toxic fumes that killed 30 people.
Once one of the tallest peaks in Indonesia, Mount Tambora now stands at 2,850 meters after its colossal eruption in 1815 reduced its size. This was the largest recorded volcanic eruption in human history and caused enough starvation and disease to kill approximately 80,000 people. Crops could not grow in its aftermath. Dubbed the "year without a summer", its outpouring of volcanic ash, sulfur, and other gases blocked sunlight for months and in turn, caused summertime snow in places as far from Indonesia as North America and Europe and changed Earth's temperature for years to come. Small eruptions of the same volcano happened in 1880 and 1967, and seismic activity was detected in 2011-2013.
The 2,460-meter volcano was dormant for centuries before roaring back to life in 2010 when an eruption killed two people. After another period of inactivity, it erupted again in 2013 and has remained highly active since. The volcano erupted in 2014, killing at least 16 people, and again in 2016, killing seven more.
Krakatau
The massive eruption of Krakatau (also called Krakatoa), a small, uninhabited island east of Sumatra and west of Java, on August 27,1883 was heard 3,000 miles away. The explosions threw five cubic miles of earth 50 miles into the air, and created 120-foot tsunamis that engulfed the shores of nearby islands killing at least 31,000 people. Another 4,500 people were scorched to death from the pyroclastic flows that rolled over the sea, stretching as far as 40 miles, according to some sources.
The dust left in the atmosphere blocked the sun and slightly lowered the global temperature temporarily, causing vivid red-glow sunsets in some parts of the world, including New York. Krakatau is still active through a vent that is continually erupting but not at dangerous levels.
Anak Krakatau
Anak Krakatau is only a century old, nothing but a speck on Earth’s timeline. But it’s already become one of the most-watched volcanoes in the world because of its incredible eruptions. The volcano also happens to be the direct descendant, so to speak, of the infamous Krakatoa (also known as Krakatau), which killed thousands of people in its historic 1883 eruption. That eruption nearly destroyed the volcano entirely. What spawned from the ash and debris was a new volcano, given the name Anak Krakatau, or “child of Krakatoa.” It rose up from the ocean in 1927 and has been active since then.
Table 1: The Deadliest Volcanic Eruptions in Indonesia
Volcanic Hazard Mitigation
Indonesia is a country with 130 volcanoes or about 13% of all active volcanoes in the world. The volcanoes are located along a 7,000 km tectonic belt. Seventy-nine of these volcanoes are classified as the most active ones, having erupted within the last 400 years. Ten percent of the Indonesian population or about 20 million people live in the volcanic areas. They enjoy several positive impacts to live there by utilizing volcanic resources. On the other hand they also are threatened by the danger of volcanic eruptions which can occur at any time. Therefore, volcanic hazard mitigation in Indonesia is especially important. The core mitigation measures implemented by the government include:
- Continuous monitoring of these active volcanoes by the Volcanological Survey of Indonesia (VSI) using 194 Seismometers, 35 CCTV, 59 GPS, 38 Tiltmeter, in 74 Observatories
- Remote sensing of topographical deformation, thermal anomaly, and sulfur dioxide levels
- Use of Electronic Distance Measurement (EDM) equipments to determine the distance from two points which allow scientists to detect inflation or deflation of a volcano due to changes in the magmatic or hydrothermal systems
- A new combination between Wireless Sensor Network (WSN), mobile robot and satellite technology for Indonesian volcano monitoring system, Mobile Monitoring System for Indonesian Volcano (MONICA) has been developed
- Use of Differential Optical Absorption Spectroscopy (DOAS) issue warning on the hazardous air pollution to the local residents
- Implementation of Multi-Tiered Volcano Early Warning System
- Geological Mapping
- Volcanic Hazard Mapping is also required, particularly in the evacuation process
- Education, training, and seminar of public authorities, first aid responders, and residents
- Lahar Control Structures
- Coordination and Cooperation with the US Geological Survey, JICA, Aid Australia, etc.
Hello John,
ReplyDeleteYour post is incredibly in-depth! The amount of effort you put into this is evident and I like how you went into detail with some of the most prominent volcanoes. It's interesting to know that Indonesia is home to the most amount of volcanoes in the world. My country too is located along the Ring of Fire, making it very hazardous. Great job!
Since my country is located near yours (Thailand), I ended up doing a bit of research on volcanoes in Indonesia as well since Thailand doesn't have any active ones. This blog was very informative, and its crazy to me that one country can have so many volcanoes. Anak Krakatau is especially interesting.
ReplyDeleteThis was an AMAZING volcanic post!-Congratulations. I have always loved the Krakatau stories...
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