Volcanic Hazards

Knowing the effects that volcanic hazards has a major impact in how we react to this disaster. This module will give you an awareness of the hazards of volcanic activity. Here is an overview of the topics that we will tackle:

  • What are volcanic hazards and when do they happen?
  • The examples of volcanic hazards.
  • It’s effects on people, homes, buildings, animals, and plants.

Volcanoes are not only a kind of landform, they also play a very important role on our planet. However, when an eruption takes place, it can be really devastating, especially if people are not aware of the bad effects that it can bring to their community.


So what are volcanic hazards?

Volcanic hazards are any possible high-risk processes of a volcano, such as an ashfall, lava flows, and pyroclastic flows. Along the subject of volcanic hazards is volcanic risk which tackles the possible occurrence of loss or destruction of lives and property.

There are many types of volcanic hazards that the world experiences. Some of these are:

  • Volcano-induced earthquakes – volcanic activity can cause shifting in the surrounding area, causing cracks in the ground and movement of plates, resulting in an earthquake that can damage homes, buildings, cars as well as death.
  • Directed blast – this happens when a volcano erupts with a blast of pyroclastic substance. This is a very dangerous volcanic hazard as it destroys everything in its way because of the speed and velocity of the blast.
Directed blast
  • Tephra – this type of volcanic hazard is similar to a directed blast, but the difference is tephras emit rock fragments and particles which are known as blocks and bombs.
  • Volcanic gases – this occurs when a volcano erupts, and it will emit gases in the sky. The gases consist of a mixture of carbon dioxide, carbon monoxide, hydrochloric acid, hydrogen, hydrogen fluoride, hydrogen sulfide, and methane. Although a large amount of the gas that volcanoes emit during an eruption is water vapor, the other gas substances can trigger respiratory infection as well as allergies and asthma if inhaled for prolonged periods of time.
  • Lava flows – this type of process in the eruption of volcanoes is considered as the least life threatening, because it happens in the vicinity of the volcano itself. There is little risk to human life, but the destruction of property can occur if the lava comes into contact with it.
Lava flow
  • Debris flows – this is a geological phenomenon where water-laden soil and fragmented rock rush down the mountainside, flow into stream channels, suck in objects in their paths, and create muddy, thick deposits on valley floors.
  • Tsunamis – this is caused by an unexpected motion of the ocean floor because of the eruption of volcanoes. Tsunamis can be very dangerous as the large body of water causes damage to everything in its path. It can also cause death of people and animals.
  • Pyroclastic surges – this is a liquidized substance which is composed of gases and particles of rocks that are emitted during a volcanic eruption.
    Pyroclastic surges

    There are three types of pyroclastic surges:

    • Base surge: A base surge is normally formed when a volcano initially starts erupting from the base of the eruption column as it collapses. It typically doesn’t travel more than 10 kilometers from the source.
    • Ash-cloud surge: forms when the eruption column is neither collapsing nor buoying material upward by convection.
    • Ground surge: these usually reside at the base of pyroclastic flows.
  • Lahars – This is one of the most destructive volcanic hazards. It can happen even if there is no volcanic eruption. It can cover a large part of the land which can cause destruction of homes, buildings, and other structures. An example of this is the eruption of Mt. Pinatubo in the Philippines in 1991.

Effects of Volcanic Hazards to Humans

  • Loss of lives and certain respiratory illnesses arise during volcanic activities, depending on the severity.
  • Loss of livestock and livelihood due to eruptions.
  • Plant life become compromised if there is a lahar flow or excessive ash fall. On the other hand, if the ash fall is just mild it can benefit the soil because it contains a lot of minerals.

The different things that we do to minimize the effects of volcanic hazards

  • Local governments from different parts of the world are putting in efforts to educating people about the hazardous effects of volcanic activities.
  • Follow disaster management plans that have been issued by the authorities.
  • Wear a protective mask to avoid inhaling the ash that comes from volcanic activity.
  • Take part in drills that the authorities implement so you have an idea of what to do if volcanic activities occur.
  • Stay away from dangerous zones if volcanic activities arise.

To conclude, volcanic hazards must be taken seriously as they can cause the destruction of lives, property, and environments. The damages that volcanic hazards can bring depends on the type of volcanic hazards, their frequency, and strength. By properly understanding volcanic hazards, you can correctly prepare yourself and your family for any outcome.

Image sources:
  1. Volcanic landslide: https://www.middaydaily.com/charged-in-mount-st-helens/25187/
  2. Directed blast: http://www.geo.mtu.edu/volcanoes/hazards/primer/dirblast.html
  3. Lahar: https://commons.wikimedia.org/wiki/File:Lahar_Mount_Pinatubo.JPG
  4. Tsunami: https://commons.wikimedia.org/wiki/File:US_Navy_050102-N-9593M-031_A_village_near_the_coast_of_Sumatra_lays_in_ruin_after_the_Tsunami_that_struck_South_East_Asia.jpg
  5. Tephra: https://commons.wikimedia.org/wiki/File:Erosion_of_tephra_layers_-_Lanzarote_03.JPG
  6. Lava flow: https://commons.wikimedia.org/wiki/File:P%C4%81hoehoe_Lava_flow.JPG
  7. Pyroclastic: https://commons.wikimedia.org/wiki/File:Pinatubo91_marella_river_pyroclastic_flow_deposits_07-01-91.jpg
  8. Earthquake: https://en.wikipedia.org/wiki/Earthquake