DRRR | Volcanic Hazards

Volcano

opening or rupture in the earth’s surface or crust that allows pyroclastic materials and gases to escape below the surface and generally found where tectonic plates are diverging or converging

Why does the Philippines have many volcanoes

We are at the boundary of the Philippine Sea plate and the Eurasian plate, which subduct beneath the archipelago. We are also located on the Pacific Ring of Fire.

Volcanic Hazards Directly Caused From Eruptions

• lahar

• pyroclastic flow/lava flow

• tephra falls/ash fall

• lateral blast/ballistic projectiles

• volcanic gases

Volcanic Hazards Indirectly Caused From Eruptions

• debris avalanche/landslide

• volcanic tsunami

• ground deformation, subsidence, fissuring

• secondary explosion

Lahar

“mudflows” or volcanic debris flows, are mixtures volcanic debris and water

Primary

“hot” lahar, from direct volcanic eruption

Secondary

“cold” lahar, caused by heavy rainfall

Impacts of Lahar

• can crush, abrade, bury, or carry away what is it in paths

• buildings and valuable land may be partially or completely buried

Ash fall

Purmice, scoria, and dense lithic materials propelled through the atmosphere in an eruption plume or an eruption column eventually falls or gravitationally settle over areas downwind of an eruption volcano, forming blankets of tephra fall or ash fall

Impacts of Ash fall

• damages vehicles and buildings

• contaminates water supplies

• disrupts sewage and electrical and sewage systems

• damages/kills vegetation

Pyroclastic Flow/Lava Flow

hot dry masses of fragmented volcanic materials that move along the slope and in contact with the ground surface

Basal flow

the pyroclastic flow itself along the ground

Ash cloud

the towering column of cloud during pyroclastic flows

Lava flow

rivers of incandescent molten rock or lava moving downslope or away from a volcanic event

Impact of Pyroclastic Flow

• asphyxiation

• live-burial

• incineration

• impact injury

• damage

• death

Ballistic Projectiles

combination of pyroclastic flows and surges with a strong laterally-directed thrust

Impact of Ballistic Projectiles

can damage infrastructures due to speed, size, and high temperatures of the material

Volcanic Gases

in the form of water vapor, hydrogen sulfide, sulfur dioxide, carbon monoxide, hydrogen chloride, hydrogen fluoride

Impact of Volcanic Gases

At 3% CO2 ratio:

• headaches

• dizziness

• increased heart rate

• difficulty breathing

• unconsciousness and death at 15%

Signs of Eruptions

• increased incidence of seismic activities

• crater ablaze due to magma

• tilting, fissuring, and inflation of the ground due to the incursion of magma

• occurrence of landslides and rockfalls not related to rain

• prevalence of dying plants/volcano near the volcano

• increased temperature of hot springs, crater lakes, and other nearby bodies of water

• springs or wells around the volcano rapidly evaporates

Volcano Alert Level 1

• low level unrest

• no eruption imminent

• activity is only within the crust

• activity may be hydrothermal, magmatic, or tectonic in origin

• no entry in the 6-km radius PDZ

Volcano Alert Level 2

• moderate unrest

• could eventually lead to eruption

• 6-km radius danger zone may be extended by 7 km in the sector where the crater rim is low

Volcano Alert Level 3

• relatively high unrest

• eruption is possible within weeks

• extension of danger zone in the sector where the crater rim is low will be considered

Volcano Alert Level 4

• intense unrest

• hazardous eruption is possible within days

• extension of danger zone in the sector to 8km where the crater rim is low will be recommended

Volcano Alert Level 5

• hazardous eruption ongoing

• pyroclastic flows may sweep down along gullies and channels especially along those fronting the low parts of the crater rim

• additional danger areas may be identified as he eruption progresses

• danger to the aircraft by way of ash cloud encounter, depending on height of eruption column or wind drift

Managing Volcanic Hazards

• predictions

• hazard maps of past eruptions

• monitoring

• evacuation plans

• post disaster relief operations

• education

Monitoring Methods

• visual observation (gas emissions, thermal anomalies, and eruptive behavior

• seismic monitoring (quakes and tremors)

• sulfur dioxide emission rate (COSPEC-correlation)

• water-level monitoring (changes on water levels and chemistry)

• ground deformation (precise leveling, tiltmeter, GPS)

Tiltmeter for Volcanoes

measures subtle changes on the surface of the volcano to search for changes in shape

GPS for Volcanoes

multiple GPS devices are placed across the volcano and the measurement changes between them are used to measure for changes between the slope

Monitoring an Active Volcano

a device called the spider monitors the seismicity (frequency of earthquakes), infrasound (sound waves from wooshing that are too low in frequency below human audibility), and volcanic lightning. It gets dropped to the crater of the volcano

COSPEC-Correlation Spectrometer

• measures SO2 emission rate

• originally developed to measure the pollution coming out of the factor smoke stacks

• makes vertical traverses through a volcanic plume

• compares the spectrum of natural light shining through clear air and the plume

What to do Before Volcanic Eruptions

• learn about your community, warning system, and emergency plans

• make evacuation plans

• develop an emergency communication plan

• prepare survival kit

What to Do During Volcanic Eruptions

• follow evacuation orders from authorities

• avoid areas downstream of the volcano

• listen to radio or TV for latest emergency information

• close all windows, doors, and dampers

• seek shelter indoors

• when caught in a rock fall, roll into a ball to protect your head

• be aware of mud flows if near a stream

What to Do After Volcanic Eruptions

• cover mouth and nose to avoid irritation of respiratory system

• wear goggles to protect your eyes

• keep skin covered to avoid irritation from contact with ash

• clear roof of ash fall

• avoid driving in heavy ash fall

• avoid contact with any amount of ash, especially if you have a respiratory ailment

• stay indoors until local health officials advise it is safe to go outside

• help vulnerable members in your community

What to Do Before Volcanic Ash Fall

• Listen to radio for updates.

• Prepare emergency supply kit.

• Prepare dust masks or clean cloth for covering the nose and goggles for eye protection.

• Prepare cleaning supplies like brooms, vacuum cleaners, spare bags, filters, and a shovel.

• Store emergency supplies in your vehicles.

• Have food and water provisions for pets, poultry, and livestock.

• Know location of evacuation area.

• Know school’s emergency plan and have indoor games/activities ready for children.

What to Do During Ash Fall

• Stay calm.

• Stay indoors.

• Cover nose and mouth with a clean and damp cloth/dust mask.

• Close all windows and doors of your house and car.

• Place damp cloth or towels near openings and doors.

• Cover all food and water containers.

• Wash all produce thoroughly before eating.

• Listen to the radio for updates.

• Keep pets inside to prevent them from inhaling ash.

• If driving, pull to the side of the road and stop as ash can cause poor visibility.

• If outside, look for shelter and wear glasses.

What to Do After Ash Fall

• Wash grass before feeding animals.

• Boil water before drinking.

• Use powder detergent when washing clothes covered with ash.

• Cover nose and mouth while cleaning ash.

• Remove ash from roof and clean with water.

• Remove ash from car doors and windows. Wash with lukewarm water and soap.

• Collect ashes and put them away from water drainage.

• Use a vacuum cleaner or clean furniture to clean ash from it.