SCIENCE

Tens of thousands of people were evacuated from an area around Mount Agung as hundreds of volcanic earthquakes were recorded in a single day. (The Australian and The Guardian)

Where is Mount Agung?

Teachers, scroll down for a quick list of key resources in our Teachers Toolkit Text Set, including today’s MapMaker Interactive map.

Discussion Ideas

• Indonesian authorities have evacuated more than 75,000 people from the island of Bali, citing concerns about major seismic activity associated with Mount Agung. Has Indonesia experienced considerable volcanic activity before? Take a look at today’s MapMaker Interactive map for some help.
  • Yes, Indonesia is an incredibly volcanic region. The catastrophic eruption of the island of Krakatoa is probably the country’s most famous volcanic incident.
  • Indonesia is the western extent of the “Ring of Fire”, a string of volcanic and seismic activity roughly ringing the Pacific Ocean. (Bali itself is in the Indian Ocean basin, however.) The Indonesian archipelago sits on the subduction zone where the Australian plate is moving beneath the Eurasian plate.

• Is Mount Agung itself an active volcano?
  • Yes, Mount Agung is a very active volcano that last erupted in 1963. The event sent volcanic debris 10 kilometers (6 miles) into the atmosphere and was responsible for the loss of more than 1,500 lives.

• Take a look at “Principal Types of Volcanoes” section in our reference resource. What type of volcano do you think Mount Agung is?
  • Mount Agung is a stratovolcano. Also known as composite volcanoes, stratovolcanoes are made up of layers of lava, volcanic ash, and fragmented rocks. These layers build up over time as the volcano erupts through a vent or group of vents at the summit’s crater.

• Take a look at the “Volcanic Hazards” section of our reference resource. What volcanic hazards do you think Indonesian authorities are most concerned about?
  • pyroclastic flows. Probably the most dangerous of all volcanic hazards, a pyroclastic flow is a fast-moving torrent of volcanic ash, lava, and gas that flows from a volcano. Pyroclastic flows are responsible for almost all the deaths associated with the last eruption of Mount Agung.
  • volcanic ash. Volcanic ash can reduce visibility, prevent air travel, damage infrastructure, and harm human health.
    • visibility. Plumes of volcanic ash can spread over large areas of sky, turning daylight into complete darkness and drastically reducing visibility.
    • air travel. Airborne volcanic ash is especially dangerous to moving aircraft. The small, abrasive particles of rock and glass can melt inside an airplane engine and solidify on the turbine blades—causing the engine to stall. The 2010 eruption of Eyjafjallajökull, Iceland, produced an ash cloud that forced the cancellation of roughly 100,000 flights and affected 7 million passengers, costing the aviation industry an estimated $2.6 billion. Check out that ash cloud here.
    • infrastructure. Ash can enter and disrupt machinery found in power supply, water supply, sewage treatment, and communication facilities. Heavy ash fall can also inhibit road and rail traffic and damage vehicles. When mixed with rainfall, volcanic ash turns into a heavy, cement-like sludge can collapse roofs.
    • health. Carbon dioxide and fluorine, gases that can be toxic to humans, can collect in volcanic ash. The resulting ash fall can lead to crop failure, animal death and deformity, and human illness. Ash’s abrasive particles can scratch the surface of the skin and eyes, causing discomfort and inflammation. If inhaled, volcanic ash can cause breathing problems and damage the lungs. Inhaling large amounts of ash and volcanic gases can cause a person to suffocate.
  • displacement. The last eruption of Mount Agung lasted about a year, and authorities fear thousands of Indonesians will be internally displaced people—a population without homes, schools, businesses, hospitals, community centers, or neighborhoods.

• Why have volcanologists and government officials become so concerned about Mount Agung over the past month?
  • Mount Agung has been the site of incredible seismic activity, recorded both on the ground and by satellites. Seismic activity includes:
    • earthquakes. Earthquakes associated with both volcanic and tectonic activity are a daily occurrence on Bali. Nearly 850 earthquakes were recorded on Monday alone. Some quakes have had a magnitude of more than 4.2 and were felt as far as 70 kilometers (43 miles) away.
    • fumaroles. Steam has been rising from fumaroles, or volcanic vents, near the summit of Mount Agong.
    • changing physical landscape. The surface of Mount Agung has bulged in some places, consistent with a build-up of underground gases.
    • heat. Data have recorded thermal anomalies consistent with magma moving beneath the Earth’s surface.

• Where are local residents being evacuated?
  • The exclusion zone is 12 kilometers (7.5 miles) around Mount Agung. Indonesia has established 377 evacuation centers on Bali, equipped with food, water, bedding, and medical supplies. The biggest evacuation center is a stadium surrounded by a tent city, which can accommodate 3,845 people. The airport remains open for those who want and are able to evacuate the island entirely.
  • According to The Australian, “Evacuating animals has become an urgent priority as it has become clear there are still a few thousand Balinese within the volcano zone who are refusing to leave their animals … ‘The main economic resource of people in this area is cattle so if we don’t save them then they will have no livelihood,’” says Bali’s agriculture chief.
  • Another major concern is Bali’s students. Only 200 of Bali’s 45,000 affected students have been relocated to other schools.

TEACHERS TOOLKIT TEXT SET

The Australian: Bali volcano set for first eruption in 54 years

The Guardian: Bali volcano: will Mount Agung erupt and what happens if it does?

Nat Geo: Where is Mount Agung? map

Nat Geo: What is a volcano? reference

Nat Geo: What is the Ring of Fire? reference

Nat Geo: What is volcanic ash? reference

Nat Geo: What is a pyroclastic flow? reference

Smithsonian Global Volcanism Program: Agung