Causes of Earthquakes
Earthquakes occur from the deformation of outer, brittle portions of "tectonic plates," the earth's outermost layer of crust and upper mantle. Due to the heating and cooling of the rock below these plates, the resulting convection causes the adjacently overlying plates to move, and, under great stresses, deform. The rates of plate movements range from about 2 to 12 centimeters per year. Sometimes, tremendous energy can build up within a single, or between neighboring plates. If the accumulated stress exceeds the strength of the rocks making up these brittle zones, the rocks can break suddenly, releasing the stored energy as an earthquake. An earthquake begins when the plates push against earth other and the pressure builds. Cracks start to appear in walls and roads. The ground may shiver (tremor). Where the rocks snap setomic waves (body waves) make the ground move. The first ones (primary) travel through rock, volcanic lava, water and even air.
There are three main plate tectonic environments: extensional, transform, and compressional. Plate boundaries in different localities are subject to different inter-plate stresses, producing these three types of earthquakes. Each type has its own special hazards.
What to do?
-Before
-During
-After
an EARTHQUAKE
What to do Before
- Determine if site is along an active fault or prone to liquefaction or landslides
- If you need help, consult PHIVOLCS
- Make sure that proper structural design and engineering practice is followed when constructing a building or house
- Check the integrity of your building;
Secure structural plan of the building
Identify structural elements
Determine condition of each structural elements
Familiarize yourself with places you're frequent
Know exit areas
- Identify safe spots:
Under a sturdy desk or table
In a strong supported doorway
In an inside corner of the room
- Identify danger zones
Glass windows and glass panels
Book shelves, machinery, cabinets and furniture that may topple or slide
Any kind of hanging objects
- Prepare place of work/residence for the event
Secure all hanging and heavy objects
Store breakables items, harmful chemicals, flammable materials in lowermost shelves and secure.
Keep heavy materials in lower shelves
Turn off gas tanks when not in use.
- Prepare
Earthquake Plan
Earthquake Survival Kit
First Aid Kit with Water Purification Tablets
AM/FM Radio
Water & High-energy Food
Tools & Ropes
Candles & Flashlights
Blankets
Tissue Paper & Waste Bags
Pencil and Paper
What to do During
- Secure an exit
When you feel an earthquake, open a door right away. This ensures an escape route after the earthquake is over.
- Do not rush
Usually a strong earthquake will end within a minute or so. Seek shelter in the room you're in and stay there until it's over.
- Go to spots
- Protect your head from falling debris
- Get away from power lines, posts, walls, other structures that may fall or collapse.
- Stay away from buildings with glass panes.
- When driving a vehicle pull to the road and stop. Do not attempt to cross bridges or overpasses which may have been DAMAGED.
- If along the shore and you feel an earthquake strong enough to make standing difficult, it is best to assume that a tsunami has been triggered. Run away from the shore toward higher ground.
What to do After
- Take emergency kit
- Get out calmly in an orderly manner. Go to an open area.
- Use the stairs. Do not use elevator.
- Check for and attend to injuries.
- Check surrounding
Check for fire and if any, have it controlled.
Clean up chemical spills, toxic and flammable materials to avoid any chain of unwanted events.
Check water, gas and electrical lines for defects. If any damage is suspected, turn the system off in the main valveor switch.
- Use flashlights; never light a match.
- Help reduce number of casualties
Don't enter partially damaged building, strong aftershocks may cause further collapse.
Gather information and disaster prevention instruction from battery-operated radios.
Obey public safety precautions/instructions
Telephone Calls
- Document observation
Damaged parts of building
Damaged utilities
Fires
School record/security logbook
Different types of Collapse
-V-Shape
-Lean To
-Pancake
