Earthquake Lecture
Earthquake Lecture
Earthquake Lecture
Earthquake is the sudden shaking of the ground that we feel when rock layers of Earth suddenly
slip past one another
The fracture in the surface of the crust where the two blocks of rocks slip is called the Fault
Faults
Active faults are areas along which all shallow earthquakes occur
Inactive faults are areas which have not displayed any seismic activity for more than thousands
of years
Types of Faults
Earthquake
Among the layers of the Earth, an earthquake originates somewhere between the crust and the
mantle
The upper mantle or the asthenosphere consists of semi-fluid materials and partially molten
rocks
The entire crust extending to the uppermost portion of the mantle is called the lithosphere
Lithospheric plates are constantly moving and because of the friction and of the rigidity of the
rocks, they cannot flow past each other
Where Does An Earthquake
Occur?
Plate Boundaries
Divergent Boundaries
A feature that exists when two tectonic plates move away from each other
Convergent Boundaries
Transform Boundaries
Mercalli Scale
Richter Scale
Effects of Earthquake
Earthquakes pose great danger and destruction because they do not happen at once
Foreshock
Aftershock
Tsunami
Tsunamis can also be produced by other natural phenomena aside from an undersea
earthquake:
a. underwater landslide
b. volcanic eruptions
c. very rarely by large meteorite impacts
Not all earthquakes can produce tsunamis. Below are the three things that will allow to generate
tsunamis:
1. Marikina Valley Fault (Montalban – San Mateo – Marikina – Pasig – Taguig – Muntinlupa – San
Pedro – Biñan – Carmona – Sta. Rosa – Calamba – Tagaytay – Oriental Mindoro)
2. Western Philippine Fault (Luzon Sea – Mindoro Strait – Panay Gulf – Sulu Sea)
3. Eastern Philippine Fault (Philippine Sea)
4. Southern Mindanao Fault (Moro Gulf – Celebes Sea)
5. Central Philippine Fault (Entire Ilocos Norte – Aurora – Quezon – Masbate – Eastern Leyte –
Southern Leyte – Agusan Del Norte – Agusan Del Sur – Davao Del Norte)
Magnitude 7.7 earthquake struck and seriously damaged Central Luzon and Baguio
The event was a result of strike-slip movements along the Philippine Fault and the Digdig Fault
Magnitude 7.2 earthquake affects the whole Central Visayas, particularly Bohol and Cebu
Generated by the North Bohol Fault
By December 6, 4,026 aftershocks were recorded, 114 of which were felt
1976 Moro Gulf Earthquake
Earthquake Preparedness
Before An Earthquake
1. Examine every part of the house – know the safe and dangerous spots
2. Repair any deep cracks in ceilings or walls
3. Bolt or fix heavy furniture to the walls
4. Have a regular inspection of the stability of hanging objects
5. Easy-to-break objects must be placed securely
6. Keep the dangerous chemicals outside the house, in the garage or outside shed
7. Turn off the gas tanks when not in use
8. Prepare a bag filled with emergency supplies and basic needs
9. Learn and practice first aid
10. Always recharge the cellphones if it is needed
11. Participate in earthquake drills
12. Unplug the appliances if not in use
13. If possible, make fire extinguisher available and put it in a safe place
14. Be familiar with the doorways or emergency exits
During An Earthquake
If indoors:
1. Stay inside, be calm and do the “Drop, Cover, and Hold”
2. Stay away where there are glass windows, shelves, cabinets, and other heavy objects
3. Be alert and keep your eyes open
4. Do not stand in doorways
5. Do not use elevators
If outdoors:
1. Move to an open area
2. If driving, do not attempt to cross bridges, overpass, or flyovers
3. If you are near the shore, go immediately to higher places
4. If you are in a crowded place, stay calm and do not rush for the doors
After An Earthquake