All About Volcanoes

• Objectives:
• Identify what a volcano is.
• Differentiate its various activity states, features, and locations.
• Name notable volcanoes in the Philippines.
• Analyze the effects of a volcanic eruption.
• Understand possible energy options for volcanic activity.

Essential Questions

• What is a volcano and what are the different types?
• Why is the Philippines riddled with volcanoes?
• What happens during volcanic eruptions?
• How is energy harnessed near volcanically active zones?

What is a Volcano?

• A rupture/opening in the Earth's crust.
• Magma beneath the Earth's crust spews out of a volcano as lava.
• Along with lava, volcanoes release ash, rocks, and hot gases.
• Volcanoes have distinct geological activities called eruptions.

Parts of a Volcano

• Internal structure consists of throat, flack vent, conduit, and magma chamber.
• External structure consists of lava and ash layers.

Differences Based on Activity

• Active Volcano:
  • Erupted at least within the last 10,000 years.
  • Shows volcanic activity in the form of volcanic quakes and/or frequent gas emissions.
• Inactive or Dormant Volcano:
  • Hasn't erupted when it is expected to erupt
  • Shows a bit of geological activity.
• Extinct Volcano:
  • Hasn't shown any sign of geological activity whatsoever.
  • Lack of eruption probably due to having no more lava supply.
  • Can become active once more in rare cases.

Differences Based on Features

• Composite Volcano:
  • Also known as a stratovolcano; it is the most common type.
  • Characterized by a crater raised above a mountainous land mass.
  • Magma usually composed of silica.
• Shield Volcano:
  • Characterized by the crater on top of a relatively broad and flat land mass.
  • Magma contains less silica.
  • Lava pouring out of shield volcano reaches farther distances at a faster rate due to its shape.
• Cinder Cone Volcano:
  • Also known as pyroclastic cones; it is the simplest type.
  • Body primarily made up of cooled pyroclastic material.
  • Lava released during eruption dries and becomes rock fragments called cinders, shaping the volcano.

Differences Based on Location

• Continental Volcano: Found on land.
• Submarine Volcano:
  • Found on the ocean floor.
  • Showcases a diverse ecosystem of chemotrophs and thermophiles that live in very hot conditions.
• Subglacial Volcano:
  • Found underneath glaciers in either land or seafloor.
  • Active subglacial volcanoes can cause massive floods called jökulhlaups from melted glacial sheets.

Volcanoes in the Philippines

• Some volcanoes in the Philippines are:
  • Mt. Kanlaon
  • Taal Volcano
  • Mt. Pinatubo
  • Mt. Bulusan
  • Mayon Volcano

Why Are There Many Volcanoes in the Philippines?

• The Philippines has hundreds of volcanoes, 53 of which are active.
• The Philippines is part of the Pacific Ring of Fire, where volcanic and tectonic activity is high.
• The Philippines needs volcano eruption and earthquake early detection devices.

What is an Eruption?

• Characterized by the discharge of lava out of the mouth of the volcano, often with smoke and ashfall.
• Volcanoes that have lava with low silica content have less violent eruptions.
• Eruptions can occur when magma cooled from previous eruptions blocks the escape of gases.
• Eruptions are caused by differences in density and pressure inside the volcano, which cannot be manipulated.
• Eruptions cannot be accurately predicted.
• Geologists, volcanologists, and seismologists give warning signals based on data from seismometers and tiltmeters.

Types of Eruption

• Phreatic: Stream-driven, short-lived eruption characterized by ash columns.
• Phreatomagmatic: Violent eruption due to contact between water and magma, producing a large column of ash and pyroclastic emissions called base surges.
• Strombolian: Weak to violent burst described by a spurting fountain of lava.
• Vulcanian: Tall eruption with columns reaching up to 20 km, causing devastating pyroclastic flow and ashfall.
• Plinian: Characterized by an explosive release of pyroclastic material, ash, and gases; eruption columns climb as high as 50 km. It is the most destructive type of eruption.

Hazards of a Volcanic Eruption

• Lava Flow: Most eruptions have lava expulsion; the land in its path will likely be destroyed.
• Volcanic Earthquakes: Strong eruptions may generate volcanic earthquakes. In volcanoes near lakes and seas, the quakes can displace water and cause a volcanic tsunami.
• Tephra Fall (Ash Fall): Particulates propelled from the volcanic plume can reach far, causing water contamination, infrastructure degradation, and trigger respiratory illnesses.
• Lahar: Volcanic mudflows are a rapid-moving mixture of volcanic debris and water that travel in river valleys.

PHIVOLCS

• The main headquarters can be found at C.P. Garcia Avenue, UP Campus, Diliman, Quezon City.
• Website can be found here: https://www.phivolcs.dost.gov.ph/index.php
• Short for "Philippine Institute of Volcanology and Seismology" under the Department of Science and Technology.
• Formed September 17, 1982, as a national institution committed to provide useful information regarding volcanic activities, earthquakes, and tsunamis.

Energy from Volcanic Activity

• Energy can be tapped from the volcanic activities of the nearby area by geothermal energy, harnessed via a geothermal power plant.
• Geothermal power plants use Earth's heat to convert water into steam, which produces energy to power a turbine that drives an electric generator and produces little to no traces of carbon dioxide, as compared with the conventional use of burning fossil fuel.

How Geothermal Power Plants Work

• Steam Tank: Absorbs heat to boil water into steam.
• Steam Turbine: Large turbine that rotates due to steam passing through it.
• Generator: Converts the mechanical energy of the steam turbine into electrical energy.
• Steam Condenser: Converts excess steam back into water.
• Injection Pump: Releases excess water back into a reservoir.
• Cooling Tower: Releases excess geothermal heat from the condenser into the air as harmless heat and steam.
• The Tiwi Geothermal Power Plant in Tiwi, Albay and the Mak-Ban (Makiling-Banahaw) Geothermal Power Plant in Calauan, Laguna, are some of the geothermal power plants.