DRRM: Volcanic Hazards

Summary

Teacher Adele's class delves into volcanic hazards, crucial for disaster risk reduction. She explains various phenomena like lava flows, which can bury and burn, but move slowly reducing immediate danger. Ash fall, or tephra, impacts visibility and agriculture, and is hazardous for aviation. Pyroclastic flows, a mix of hot gases and volcanic materials, can cause widespread destruction and asphyxiation. Lahars, volcanic mudflows, and other hazards like gas emissions and landslides are also covered, providing a comprehensive understanding of volcanic risks.

Takeaways

• 🌋 Volcanic hazards are phenomena arising from volcanic activity that pose potential threats to people and property.
• 🔥 Lava flows are streams of molten rock that can bury, crush, cover, and burn everything in their path, rendering affected areas useless for agriculture.
• 🌬️ Ash fall or tephra fall consists of fine to coarse volcanic particles that can cause low visibility, damage to agriculture, and pose risks to aircraft.
• 💨 Pyroclastic flows are turbulent masses of ejected volcanic materials mixed with hot gases that can move at high speeds and cause widespread destruction.
• 🌪️ Surges are more dilute and mobile derivatives of pyroclastic flows, consisting mostly of ash and gases, which can cause asphyxiation and burn injuries.
• 🌊 Lahars are rapidly flowing mixtures of volcanic sediments and water that can cause significant damage and are often triggered by heavy rainfall.
• 🌫️ Volcanic gases and aerosols released into the atmosphere include harmful substances like hydrogen sulfide, sulfur dioxide, and carbon monoxide.
• 🗻 Debris avalanches or volcanic landslides occur when a massive part of a volcano collapses, often due to earthquakes or eruptions.
• 🎯 Ballistic projectiles are volcanic materials ejected with force and trajectory, posing direct hazards to surrounding areas.
• ❗️ The effects of volcanic hazards can be far-reaching, as exemplified by the global impact of the 1991 Mount Pinatubo eruption.

Q & A

What are volcanic hazards?

Volcanic hazards are phenomena arising from volcanic activity that pose potential threats to persons or property in a given area within a certain period of time.

What is the primary hazard posed by lava flows?

Lava flows can bury, crush, cover, and burn everything in their path. They can render affected areas useless for agricultural use for years due to the solid nature of the lava deposits.

How fast do lava flows typically move?

Lava flows move at varying speeds, from a few centimeters per hour for viscous flows to several kilometers per hour for basaltic flows.

What is ash fall and how does it affect visibility and agriculture?

Ash fall, or tephra fall, consists of airborne fine to coarse-grained volcanic particles that can cause poor visibility and loss of agricultural land. It can also be dangerous for aircrafts as abrasive ash can cause engine failure.

What is the global impact of ash fall from a volcanic eruption?

The ash fall from a volcanic eruption can affect not just the local area but the entire world, as seen with the 1991 eruption of Mount Pinatubo in the Philippines.

What are pyroclastic flows and surges?

Pyroclastic flows are turbulent masses of ejected fragmented volcanic materials mixed with hot gases that flow down slope at high speeds. Surges are more dilute and mobile derivatives of pyroclastic flows.

What hazards are associated with pyroclastic flows?

Pyroclastic flows can destroy anything in their path by direct impact, burn surfaces with hot rocks, and cause asphyxiation or inhalation of hot ash and gases.

What is a lahar and what does it consist of?

A lahar is a rapidly flowing thick mixture of volcanic sediments, pyroclastic materials, and water, which can cause significant damage and flooding.

What are volcanic gases and which ones are commonly released?

Volcanic gases include water vapor, hydrogen sulfide, sulfur dioxide, carbon monoxide, hydrogen chloride, and hydrogen. These gases can have harmful effects on the environment and human health.

What is a debris avalanche or volcanic landslide?

A debris avalanche or volcanic landslide is a massive collapse of a volcano's slope, usually triggered by an earthquake or volcanic eruption.

What are ballistic projectiles and how are they formed?

Ballistic projectiles are volcanic materials that are directly ejected from the volcano's vent with force and trajectory, often during explosive eruptions.