earthquake hazards and risk reduction methods

fault

a fracture in the rocks that make up the earth’s crust

epicenter

surface of the earth directly above the focus

focus

the point within the earth where an earthquake rupture starts

tectonic plate

massive rocks that make up the outer layer of the earth’s surface and where movements along faults triggers earthquakes

seismic waves

waves that transmit the energy released by an earthquake

earthquake hazards

refers to earthquake agents which have potential to cause harm to vulnerable targets which can either be humans, animals, or even the environment

• primary

• secondary

types of earthquake effects

primary effects

are permanent features an earthquake can bring out

ex: fault scraps, surface ruptures, and offset of human-constructed objects

secondary effects

it happen when ground movement results to other type of destruction

ex: landslides, tsunami, liquefaction, and fire

• effective recording and interpretation of ground motion

• constructing seismic hazard maps

• developing resistant structures

most common methods of reducing earthquake risk

the pacific ring of fire

an area recognized to have frequent and active earthquakes and volcanic eruptions where the philippines is situated

western edge or the western boundary

another geological explanation why the philippines is prone to ground movement is that the _______________________ of the philippine plate runs along the midsection of the philippines

200 to 250 earthquakes

how many earthquakes does the philippines experience every year?

ground shaking

the shaking of the ground is caused by the passage of seismic waves (forms of energy) that travel through the different layers of earth caused by vibration or movement

ground rupture

this occurs when ground movement happens on a fault line and breaks through to the surface, this may happen in an instant during an earthquake

liquefaction

this occurs when seismic shaking causes loose materials in the soil to mix with groundwater or soil saturated with water, eventually, the soil behaves like a quicksand that has lost its strength to hold and support objects on top of it

earthquake-induced ground subsidence

is the lowering of land due to various causes, one of which is the earthquake on a fault line, the movement of the ground during an earthquake could be horizontal, vertical, or both

harbor wave

what does the japanese word “tsunami” means

tsunami

used to describe a series of waves that are generated by a sudden displacement on the ocean floor caused by large-scale undersea landslide or earthquake, submarine volcanic eruption, or even a large meteor crash at sea

earthquake-induced landslide

may happen during or after an earthquake when a weakened section of landfalls off primarily due to gravity

• deforestation

• excavation

• mining

• quarrying or sudden breakup of soil due to thunder

reasons why land becomes weak

seismometer

is an instrument used to measure movements in earth’s surface that can detect vibrations from seismic waves generated by earthquakes and volcanic eruptions