Volcanic Hazards

Volcanoes

• Volcanoes are openings in Earth's crust that allow energy to escape to the surface
• Magma, composed of molten rocks from Earth's mantle, releases energy as lava, ash, and gas
• The Earth's crust is broken up into tectonic plates leading to volcanos
• Most volcanoes are found on the edges of tectonic plates where one plate connects to another
• There are more than 20 active volcanoes

Volcanic hazards

• Lahar: a mixture of water, pyroclastic materials, and rock fragments flowing down a volcano or river valley,
• Ash Fall: composed of bits and pieces of pulverized rock, minerals, and volcanic glass. Fragments measure 2mm
• Volcanic ash is usually spewed out from explosive eruptions when dissolved gases in magma expand
• Some ash forms clouds, especially during humid and dry weather
• Ash falls slowly and can destroy structures and buildings, destroy agricultural land, clog air filters of vehicles and machinery and wet ash can be slippery
• Airborne particles from ash can have adverse health effects
• Pyroclastic Flow: a fast-moving fluidized mass of rock fragments and gases, maintaining very high temperatures as it travels down a volcano. The flow from Mt. Pinatubo was 750C
• Gases with pyroclastic flow that can explode may even cause acid rain
• Ballistic Projectile: a rock fragment ejected from a volcano during an explosive eruption
• Volcanic projectiles can be bombs, launched in a partially molten or molten state, or be solid blocks
• Ballistic Projectiles can travel 5km or even further
• Volcanic Gas: consists of sulfur dioxide and hydrogen sulfide which are poisonous to organisms
• SO2 and H2S are constituents of magma during an eruption
• Excessive composition of volcanic gas can cause acid rain
• Elements exposed to volcanic gas can be prone to corrosion

Lava Flow

• Molten rock that pours down from the slopes of the volcano
• Lava flow is denser and moves more slowly
• It can kill vegetation, roads, and destroy properties
• Forest fires can be ignited by lava flow

Signs of an Impending Volcanic Eruption

• Occurrence of tremors or increase in the frequency of small earthquakes.
• Deformation in the ground manifested by changes in ground elevation (tilting) and formation of cracks or openings (ground fissuring).
• Increase in the amount of volcanic gases and in temperature, which may indicate that the magma has gone closer to the surface.
• Glow of volcanic crater due to the presence of magma.
• Increase in steam emission coming from volcanic openings, fissures, or hot springs.
• Thermal changes within the surroundings of the volcano.
• Change in the color of nearby vegetation and lakes.
• Landslides and rockfall not due to heavy rains.
• Drying up of springs and freshwater sources around the volcano

Interpreting Volcanic Hazard Maps

• Volcanoes are scattered from north to south of the Philippines.

Precautionary and Safety Measures Before a Volcanic Eruption

• Stay updated with the local news
• Learn about your community warning systems and emergency plans. Have a meeting with all family members to makes sure each member is informed of your plan and knows where the emergency supply kit is
• Prepare an emergency supply kit that should include the following: first-aid kit, clean clothes, food and water, flashlight with extra batteries, battery-operated radio, prescribed medicines, dust masks, goggles, and sturdy shoes
• Pack all important and essential items in light and waterproof containers
• Secure livestock in enclosed shelters
• Listen to public safety announcements of local authorities and evacuation instructions if they tell you to evacuate the area

During an Eruption

• Follow evacuation orders issued by local authorities and remind family members of your disaster plan. Stay in the evacuation center until further instructions are given
• If told to stay indoors, place a damp cloth over your windows and, if possible, over your doors. Make sure all windows, doors, and other vents are kept closed to prevent entry of ash and other materials spewed out by the volcano. The wet cloth will help keep fine volcanic particles from entering your house.
• Wear long-sleeved shirts and long pants
• Use goggles to protect your eyes
• Use a dust mask or hold a damp cloth over your face to prevent inhalation of ashes and other volcanic particles. This will also help you breathe easier
• Avoid low-lying regions and river areas near the volcano. Volcanic debris and ash will be carried by the wind and gravity
• Listen to a battery-operated radio for the latest emergency information.

After an Eruption

• Wait for the announcement from local authorities that it is safe to return to your house
• Inspect your house carefully for any damage before you enter it. Do not enter your house if you smell gas, lahar is present, or authorities have declared it unsafe
• If you or a family member has a respiratory ailment such as asthma or bronchitis, stay away from volcanic ash fall areas
• Wear a dust mask, gloves, and goggles while cleaning the debris and ash fall on the roof of your house to avoid further damage
• Check electrical wirings, appliances, and gas tanks before using them
• Boil water before drinking it as groundwater pipes may have been contaminated by volcanic particles
• Stay informed and listen for emergency updates and news