Faults Flashcards
(23 cards)
Fracture or break in the earth’s crust where earthquakes are most likely to occur repeatedly.
FAULT
How are faults formed?
Rocks of the crust are compressed or stretched by plate movement
Are numerous or many faults spread over a wide area.
fault zones
FORCE APPLIED TO ROCKS
STRESS
Rocks that are stretched AWAY from each other
TENSIONAL-ROCKS
Rocks that are Pushed TOWARDS each other.
COMPRESSIONAL-ROCKS
Rocks that are Pushed TOWARDS each other but not in the same axis; can cause masses of rocks to slip
SHEAR-ROCKS
When rocks are stretched or compressed along the horizon, they break and from a fault plane at an angle to the horizon.
DIP-SLIP FAULTS
Are dip-slip faults where the block that sits on the fault plane called hanging wall has MOVED DOWNWARD
Normal Faults
Are dip-slip faults formed when rocks are compressed where the hanging wall MOVES UP
Reverse faults
Rocks are made to shear, they break along a fault plane that forms in the direction of the shear.
It slips in the direction of the strike
STRIKE-SLIP FAULTS
Left block moves toward you and the right block moves away
Left-lateral
Strike slip faults
Right block moves toward you and the left block moves away
RIGHT-LATERAL STRIKE-SLIP FAULTS
When shearing and tension combine. They move along both the dip and strike directions
OBLIQUE-SLIP FAULTS
Are known to have recently generated earthquakes within the last 10,000 years and may still continue to generate earthquakes.
ACTIVE FAULTS
The most extensive fault system and cuts through the entire archipelago
Affected areas: Ilocos Norte, Aurora, Quezon, Masbate, Eastern Leyte,
Southern Leyte, Agusan Del Sur, Davao Del Norte.
Left lateral strike slip type that moves 2-3cm Per year
(PFZ) PHILIPPINE FAULT ZONE
Is the most geologically active fault line in the Philippines.
Affected Areas: Montalban, San Mateo, Marikina, Pasig, Taguig, Muntinlupa, San Pedro, Binan, Carmona, Santa Rosa, Calamba, Tagaytay, Oriental Mindoro
4 significant earthquake events in the last 1500 years
WEST VALLEY FAULT
A left-lateral strike-slip fault along Verde Island passage but becomes an oblique slip as it runs closer to the Manila Trench
Lubang Fault
Marked by a break in slope between the mountains of western Mindoro and flatlands of eastern mindoro.
Right-lateral strike-slip fault but is also normal dip-slip movement
Caused 1994 magnitude 7.1 earthquake
CENTRAL MINDORO FAULT
Are faults that do not show signs of ever having generated an earthquake in the last 10,000 years but may possibly still generate an earthquake in the future
INACTIVE FAULTS
Stored energy on materials that can be compressed or stretched.
Elastic Potential Energy
Kinetic energy released when rocks break along a fault
Seismic Energy
Seismic energy passing through rocks and spread from their point of origin towards the earth’s surface
Seismic Wave
