Volcanic Hazards Overview

Lava Flows

• Lava flows composed of low silica magma have low viscosities and flow at high speeds (kilometers per hour)

Volcanic Hazards

• Tephra (Ashfall): Tephra (fragmented volcanic particles) or ash (particles less than 2 mm in diameter) are propelled through the atmosphere and fall downwind, forming blankets of tephra fall or ashfall.
• Pyroclastic Density Currents (PDCs): Mixtures of fragmented volcanic particles, hot gases, and ash that rush down volcanic slopes or outward from a vent at high speeds.
• Lateral Blasts: Laterally-directed thrusts of hot gas and ash generated from an exploding dome on the summit vent or inside the edifice when the volcanic flanks fail.
• Volcanic Gas: Gases dissolved in magma are released during eruptions. The principal volcanic gases are water vapor, hydrogen sulfide, sulfur dioxide, carbon dioxide, carbon monoxide, hydrogen chloride, and hydrogen fluoride.
• Lahar: Slurries of volcanic sediment, debris, and water that cascade down volcano slopes through rivers and channels.
• Debris Avalanche (Sector Collapse): Mass failure of the flanks of a volcano edifice due to magma intrusion, earthquakes, or fault movements beneath the edifice.
• Ground Subsidence and Fissuring: Ascending magma can cause fissures in the ground, typically along fractures or faults. Magma removal can lead to ground subsidence and further fissuring, often accompanied by earthquakes.
• Secondary Explosions, PDCs, and Ashfall: Secondary explosions can occur when hot volcanic deposits come into contact with water leading to small-scale PDCs and minor ashfall.

Factors Affecting Volcanic Eruption

• Viscosity: Fluid's resistance to flow
• Gas Content: The amount of dissolved gases in magma
• Magma Composition (Silica Content): The higher the silica content, the more viscous the magma

Types of Volcanic Eruption

• Icelandic/Hawaiian: Massive amounts of very hot, thin, runny lava flooding the Earth's surface, with the main difference being that Hawaiian eruptions primarily erupt from the summit vent.
• Strombolian: Short-lived explosive eruptions shooting thick, pasty lava, steam, and gas into the air.
• Vulcanian: More violent and explosive than Strombolian eruptions, containing high dark clouds of steam, ash, and gas.
• Pelean: Explosive outbursts generating pyroclastic flows, dense mixtures of hot volcanic fragments and gas.
• Plinian: The most explosive type, characterized by powerful eruptions that send ash high into the atmosphere.

Preparing for a Volcanic Eruption

• Develop evacuation and shelter plans: Ensure everyone understands them.
• Prepare necessary supplies: Flashlight with extra batteries, first aid kit, emergency food and water, manual can opener, essential medicines, sturdy shoes, respiratory and eye protection, a battery-powered radio.
• Follow authorities' instructions: Tune in to radio/television for volcano updates, listen to disaster sirens.
• Gather emergency supplies: Pack a 1-week supply of prescription medications.
• Prepare an emergency kit for your vehicle: Include food, flares, booster cables, maps, tools, a first aid kit, a fire extinguisher, sleeping bags, flashlight, batteries, etc.
• Fill your vehicle's gas tank

Geothermal Power Plant

• Energy generation: Water is pumped into the earth where it's heated by geothermal energy.
• Water turns to steam: When the water reaches the surface, the drop in pressure causes it to turn into steam.
• Steam spins a turbine: The spinning turbine drives a generator to produce electricity.
• Cooling tower cools the steam: The steam condenses back into water.
• Water is pumped back into the earth: The cooled water is pumped back into the earth to continue the process.

Positive Effects of Volcanoes

• Creates spectacular scenery
• Produces rich soil for farming
• Can cause a decrease in Earth's surface temperature
• People become creative, using ashfall to make earthenware

Negative Effects of Volcanoes

• Causes loss of lives
• Damages properties
• Causes air pollution
• Causes water pollution

Taal Volcano Alert Level Scheme (PHIVOLCS)

• Alert Level: Represents the overall condition of the volcano, with levels 1-5 indicating increasing severity of unrest.
• Monitoring Criteria: Parameters from instrumental, visual, and sensory observations acquired by Volcano Observatories.
• Interpretation: Explaining the probable processes within the volcano based on monitoring criteria and potential dangers.
• Recommendations: Response measures for public safety, implemented by local and national government units.
• Step-Down Criteria: Conditions needed to lower the alert level.

Explore the various volcanic hazards including lava flows, tephra, pyroclastic density currents, and volcanic gases. This quiz will test your understanding of how these phenomena occur and their impacts on the environment. Prepare to dive into the dynamics of volcanic activity and its hazards.