Source: The Print
Context
A series of intense volcanic eruptions at Indonesia’s Mount Anak Krakatau blanketed Jakarta and surrounding provinces in dense ash clouds, forcing suspension of flights at Jakarta airport.
What It Is
- An active volcanic island and stratovolcano, featuring a pyroclastic cone
- The name means “Child of Krakatoa” in Indonesian
Formation and Origin
- Emerged within the marine caldera created by the catastrophic 1883 VEI-6 eruption of Krakatoa, which destroyed two-thirds of the original island
- Submarine eruptive activity began in early 1927
- Repeated cycles of basaltic accumulation breached the ocean surface, rising permanently above sea level on 11 August 1930
Important Facts for Exams
- Anak Krakatau — “Child of Krakatoa”; in the Sunda Strait, between Java and Sumatra, Indonesia
- Emerged from the caldera of the 1883 Krakatoa eruption (VEI-6); rose above sea level on 11 August 1930
- Lies within Ujung Kulon National Park, a UNESCO World Heritage Site and last refuge of the Javan rhinoceros
- On the Pacific Ring of Fire; about 700 km north of the Sunda Trench
- Indo-Australian Plate subducts beneath the Sunda Plate — a convergent boundary
- December 2018 flank collapse caused the Sunda Strait tsunami — a volcanogenic tsunami, not seismic, which is why no earthquake warning preceded it
- VEI — Volcanic Explosivity Index, a 0–8 logarithmic scale
- Eruption types: Strombolian (mild, frequent bursts), Vulcanian (more explosive, ash-rich), Plinian (most violent)
- Stratovolcano — a steep, layered cone of lava and pyroclastic material; Somma volcano — a new cone growing inside an older caldera
- Indonesia has the most active volcanoes of any country; other notable ones: Merapi, Tambora, Semeru, Sinabung
- Mount Tambora (1815) was the largest eruption in recorded history, causing the “Year Without a Summer” in 1816
