NATURAL HAZARDSEarthquake and Volcanic

The minimal to rapid shaking of the ground due to the movement of rocks

along fractures known as faults.

EARTHQUAKEHAZARDS

There are so many things that can happen

during or after an earthquake

Specifically disasters or ‘hazards’

WHAT ARE THOSE?

SURFACE RUPTURE AND PHYSICAL DAMAGE

• Is the most obvious hazard of an Earthquake

• Breaking of the ground, (Uplift and Subsidence); and

• Buildings collapsing

Earthquakes with higher energy create stronger ground motion

LIQUEFACTION

• Is the mixing of sand or soil and groundwater (underground water) during the

shaking of an Earthquake.

• Buildings can even sink into the ground if soil liquefaction occurs.

It is a hazard specially in areas that have groundwater near the surface and sandy soil

Liquefaction

+

Subsidence

HOW DOES

HAPPEN?

• When the water and soil are mixed, the ground becomes very soft and

acts similar to quicksand

If liquefaction occurs under a building, it may start to lean, tip over, or sink several feet.

• The ground firms up again after the earthquake has past and the

water has settled back down it usual place deeper in the ground.

• It can break out during or after an earthquake when damage happen along electric

power lines, substations, and power plants.

Fire after earthquake in Biratnagar, Nepal

• It can also occur when Ground Rupture creates gas leaks

• Also called harbor wave, is an earthquake hazard that is generated when

earthquakes occur on the seafloor.

• Occurs when there is too much shaking of the ground, which loosens the soil,

facilitating its downward movement.

Landslide may occur as a result of broken off pieces of land.

Most of the hazards to people come from man-made structures

themselves and the shaking they receive from the earthquake. The real

dangers to people are being crushed in a collapsing building, drowning

in a flood caused by a broken dam or levee, getting buried under a

landslide, or being burned in a fire.

Although landslide is an Earthquake hazard, it could also be triggered by other factors

such as heavy rainfall, deforestation, human activities, and etc.

VOLCANICERUPTIONS

+ HAZARDS

QUICK FACT

Earthquakes are sometimes used in predicting

volcanic eruptions

It alerts the authorities to observe a nearby volcano.

Active volcanoes are the ones that are usually closely monitored by Volcanologist.

Two types of

*Depending on the magma composition.

BASED ON MAGMA COMPOSITION

Explosive Type

• Highly viscous magma

• Contains large amounts of dissolved

gases.

Hawaiian / Non-Explosive Type

• Low viscous magma

• Contains low amount of dissolved gases.

Magma could not easily get out, that’s why it

builds up pressure resulting to an explosion.

VISCOSITY?

Viscosity determines the ability of magma to flow

The lower viscosity, the easier it is for the magma to flow.

• The viscosity of magma is affected by and

Silica

Content

TemperatureSilica

Content Temperature

High Viscosity Low Viscosity

Explosive Type Non-Explosive Type

Explosive volcanic eruptions release pyroclastic flows and materials that are

considered to pose the greatest threat.

• Pyroclastic flows often render people unable to run since they become overwhelmed with what

they are seeing.

Pyroclastic Flow

• Too much pyroclastic material, may bury people and severely damage the

agricultural land and livestock; and somehow lead to FAMINE.

• After an eruption, pyroclastic material that have settled along the slope of the

volcano get mixed with rainwater… Starting a mudflow or LAHAR.

Lahar moving at high speed and destroying everything along its path.

• Poisonous gases are also released by volcanoes.

• Volcanic eruption can also happen underwater, which can trigger a

Earthquake Hazards

Volcanic Eruption + Hazards

Earthquake HazardsSurface Rupture & Physical Damage

Liquefaction

Fires

Tsunami

Landslide

Volcanic EruptionTwo Types; based on magma comp.

1. Explosive Eruption

2. Non-Explosive Eruption

Volcanic HazardsPyroclastic Flows and Materials

People unable to run

Bury people and agriculture

Mudflow or LAHAR

Poisonous gases

Tsunami

MITIGATIONAND

ADAPTATION

MITIGATION

Is the effort to reduce loss of life and property by lessening the impact of disasters.

• In order for mitigation to be effective, we need to take action now before the next

disaster – to reduce human and financial consequences later.

ADAPTATION

Is to reduce our vulnerability to the harmful effects of natural disasters.

• Adapting to life in case of disasters involves adjusting to actual or expected future disasters.

The Philippines is located in a disaster risk area, and hazards will always be present.

HAZARD MAPS

• One of the government’s response to mitigate and adapt to the hazards.

• Developed to indicate the places where most of the natural disasters usually occur

and will most likely occur.

With this, people can be informed and can create an emergency response plan.

There can be reduction and mitigation of the dangers of these natural disasters to life and property

Flood Hazard Map in Marikina Earthquake Hazard | Risk in MM

Aside from Hazards Maps to mitigate and adapt to natural disasters,

Action plans should be conceptualized to identify the priorities for action and plan

for the possible impacts affecting the country.

Local Programs should also be established to help the people who are most affected

by natural disasters to recover from their losses and also train them think out of the

box.

Education | Knowledge is also a means for people to mitigate and adapt to

natural disasters.

In preparation for natural disasters, information regarding what to do before, during,

and after a natural disaster is disseminated all over the country.

Before During After

Be aware of the earthquake

evacuation plans for all the

buildings you occupy regularly

Duck under a sturdy desk

or table and hold onto it.

Protect your head with

your arms.

Check yourself and

others for injuries.

Before During After

Prepare an emergency

disaster plan for you and

your family

Do not panic; stay calm. Check your house for

damage.

Before After

Be aware of landslide-susceptible areas

in your neighborhood.

Stay away from the slide area since the

land may still be loose and it may still

occur.

Earthquake

Landslide

Volcanic

Eruption

END OF PRESENTATION

INDEX

• by the shaking itself or by the ground beneath them settling to a different level than

it was before the earthquake (subsidence) or (uplift).

• Subsidence is the motion of a surface (usually, the Earth's surface) as it shifts

downward relative to a datum such as sea-level.

• A fault is a fracture or zone of fractures between two blocks of rock. Faults allow the

blocks to move relative to each other.

• Philippines experience a lot of Earthquakes because it is located in the Circum-

Pacific Belt, situated in the Pacific Ring of Fire

• Pacific Ring of Fire is term used for VOLCANOES only.

TWO TYPES OF VOLCANO

• The viscosity of the magma is affected by Silica content and temperature

HAZARD MAPS

• The Department of Environment and Natural Resources (DENR) are responsible for

Hazard Maps.

INDEX