(SEM1Q1, SCI) 1.1 - Types of Faults

What was one of the deadliest earthquakes in the Philippines in the span of 23 years?

Sagbayan, Bohol Earthquake (Oct 15, 2013 - Magnitude 7.2)

What causes earthquakes?

rapid release of energy

What are the stresses the energy stored in rocks are subjected to? (3)

expansion, compression, shearing

What happens when the strength of the rock is exceeded?

It breaks and causes vibrations.

Where do earthquakes happen?

along faults

What are faults?

a fracture in the Earth's lithosphere in which blocks of rocks move past each other

How is a fault formed?

rocks are pulled or pushed by the motion of the plates

What happens when the stress on the edge overcomes the friction?

The ground suddenly moves.

Why does the Philippines have many fault zones?

It is located within the Ring of Fire.

What is the pacific Ring of Fire?

a region in the pacific ocean prone to earthquakes and volcanic eruptions

What are the three types of faults according to movement?

normal, reverse, strike-slip

What is a normal fault?

block of rock above the fault plane slides down relative to the other rock

How is a normal fault created?

tension when rocks get stretched out or expands and is thinned in the middle

What is a reverse fault?

block of rock above the fault plane moves up relative to the other block

How is a reverse fault created?

created by the compression of the rock until it folds or breaks

What is a strike-slip fault?

vertical fractures where blocks move horizontally

How is a strike-slip fault created?

stress from shearing forces or pushing of rock in opposite directions

What is a left-lateral strike-slip fault?

block on the far side of the fault moves left

What is a right-lateral strike-slip fault?

block on the far side of the fault moves right

What is an active fault?

a fault that has generated earthquakes within the last 10,000 years

What is an inactive fault?

a fault that has not generated earthquakes in the last 10,000 years

How can you find the level of activity of a fault?

by checking the historical records

How is an inactive fault generated?

through rapid erosion or widespread urban development

What is another name for left-lateral strike-slip fault?

sinistral

What is another name for right-lateral strike-slip fault?

dextral

What are the 5 active faults in the Philippines?

(1) central philippine fault
(2) marikina valley fault
(3) western philippine fault
(4) eastern philippine fault
(5) southern mindanao fault

What is another name for the Marikina Valley Fault System?

Valley Fault System (VFS)

What is the Marikina Valley Fault system?

a dominantly dextral strike-slip fault system in Luzon

What is the hanging wall or headwall?

the upper or overlying block along the fault plane

What is the footwall?

the lower or underlying block along the fault plane

When the hanging wall of a fault slips downward in respect to the footwall, what kind of fault is produced?

normal fault

Deformation is the breaking, tilting, and folding of rocks caused by?

stress

What type of fault uplifts rock and creates fault-block mountains?

normal faults

How does stress affect Earth's crust?

It causes deformation and can deal damage.

What is the stress in the crust that results in the formation of folded mountains?

Compression

How are plateaus formed?

vertical faults push up a large flat block of rock

Stress causes compression that produces what kind of fault?

reverse fault

Stress causes tension that produces what kind of fault?

normal fault

Stress causes shearing that produces what kind of fault?

strike-slip fault