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PHIVOLCS

• philippine institute of volcanology and seismology

• provides info on earthquakes and volcanic activity

Earthquakes

• the shaking of earth

• caused by waves on and below the earth's surface

Epicenter

• point on the earth’s surface above focus

Focus

• point at which the earthquake rupture begins

Magnitude

• measure of energy release 

• earthquakes only have ONE magnitude

• measured by Richter Scale

Intensity

• measure strength of shaking produced by the earthquake

• the damaged caused

• measured by Mercalli Scale

Ground Shaking

• primary cause of earthquake damage to man-made structures

• damage depends on

  • topography

  • geologic conditions

  • bedrock

  • location of fault

  • distance to epicenter

• how is it measured

  • from logarithm of amplitude waves recorded by seismographs

• impacts

  • damaged structures

  • injuries

  • loss of lives

• how to reduce vulnerability

  • understanding how damage occurs

  • evaluation earthquake-resistant design strategies

Earthquake Induced Ground Subsidence

• lowering of the land surface

• impacts

  • cracked infrastructures

  • changes in elevation

  • broken pipes and utility

  • disrupted drainage

  • injury/death

• how is it measured

  • elevation change

  • interferometric sysnthetic aperture radar

  • continuous gps measurements

  • campaign global positioning system surveying

  • spirit-leveling surveying

• how to reduce vulnerability 

  • public information programs

  • maps

  • land-use management

Landslide

• movement of land, earth, rock, or debris downslope due to gravity

• impacts

  • damage to property

  • disruption of transportation

  • loss of agricultural sources

  • death

• how is it measures

  • by movement of land mass monitored by GPS

• how to reduce vulnerability

  • identity prone areas

  • engineering solutions

  • vegetation and landscaping

  • water management

  • regulation and zoning

Liquefaction

• water saturated soil loses its strength and acts like quicksand

• causes sinking and tilting of building

• how to reduce vulnerability

  • ground improvement engineering

  • select areas where soil is not predominantly sand

Tsunami

• displacement of large body of water surging over land

• sings

  • strong ground shaking

  • unusual sea-level fluctuations

  • abnormally huge wave

  • loud ocean roar

• how is it measured

  • tsunami buoys collect data about changeed in water levels

• causes of damage

  • high velocity impact

  • inland distance of wave runup

  • vertical distance of wave runup

  • inadequate resistance of buildings

  • flooding inadequate horizontal and vertical evacuation

  • proximity to source of tsunami

• impacts

  • damage to: properties, infrastructures

  • death due to drowning

• how to reduce vulnerability

  • land use management

  • planting and environmental preservation

  • structural designs

  • hazard awareness

  • tsunami warning

Faulting/Ground Rupture

• movement of ground along on side of a fault

• how it is measured

  • in distance/area

  • rupture area of fault increases with magnitude

• impacts

  • damage to: structures, infrastructures

  • broken pipes and utility

  • injuries and death

• how to reduce vulnerability

  • select location far from fault line

  • government should provide zones

  • engineering designs

Summary

• groundshaking

• earthquake induced ground subsidence 

• landslides

• liquefaction

• tsunami

• ground ruptures

Local Strategies

• be aware of earthquake risks

• live in earthquake resistant house

• sources of open flame and appliances must be stable and safe

• earthquake drills

• first-aid training groups

General Strategies

• construction must be have higher standard of quality

• implement location planning to reduce urban density

Before an Earthquake

• prepare emergency kits

• secure heavy objects

• reinforce structure

During an Earthquake

• drop, cover, and hold

• stay indoors

• stay away from hazards

• if outdoors, move to open area

After an Earthquake

• check for injuries

• be prepared for aftershocks

• evacuate if necessary

• listen to official instructions

• check utilities and document damages

Seismology

• study of earthquakes and seismic waves

Seismic Waves

• vibrations made by sudden impulse in the earth

Seismograph

• records ground movement using seismometer

Seismometer

• main component of siesmograph that records ground motion caused by seismic waves

Surface Waves

• waves recorded on the surface of of the earth

• slower than body waves 

• does the damage in earthquakes

Types of Surface Waves

• rayleigh waves

  • shakes the ground like rolling ocean waves

• love waves

  • shakes the ground side-to-side in an S shape

Body Waves

• waves recorded in the interior of the earth

Types of Body Waves

• primary (p-waves)

  • fastest

  • cause matter to move forward and backward

  • has a PUSH-PULL motion (compression and dilation)

• secondary (s-waves)

  • cause matter to oscillate side to side (perpendicular to the motion)

  • shears the rock that they pass through