Earthquake and Faults

8/11/2019 Earthquake and Faults

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Earthquake and Faults


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Layers of the Earth

The interior structure of the Earthis

layered in spherical shells, like an onion.
http://en.wikipedia.org/wiki/File:Earth_poster.svg


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Layers of the Earth

Outer Silicate Crust

Mantle

Liquid Outer Core

Inner Core
http://en.wikipedia.org/wiki/File:Slice_earth.svg


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Layers of the Earth

Structure of Earth by Definition:

by Mechanical Properties

by Chemical Properties


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Layers of the Earth

By Mechanical Properties:

oLithosphere

oAsthenosphere

oMesopheric Mantle

oOuter CoreoInner Core


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Layers of the Earth

By Chemical Properties:

oCrust

oUpper Mantle

oLower Mantle

oOuter CoreoInner Core


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Layers of the Earth

DEPTH

Kilometers Miles Layer

060 037Lithosphere (locally varies between 5 and

200 km)

035 022 Crust (locally varies between 5 and

70 km)

3560 2237 Uppermost part of mantle

352,890 221,790 Mantle

100200 210-270 Upper mesosphere (upper mantle)

6602,890 4101,790 Lower mesosphere (lower mantle)

2,8905,150 1,7903,160 Outer core

5,1506,360 3,1603,954 Inner core


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Plate Tectonic

Plate tectonics(from

the Late Latin

tectonicus,

"pertaining to

building")

is a scientific theory that

describes the large-scalemotion of Earth's

lithosphere.


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Plate Tectonic

The geoscientific

community accepted the

Theory after the concepts of

seafloor spreading were

later developed in the late

1950s and early 1960s.
http://en.wikipedia.org/wiki/File:Farallon_Plate.jpg


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Plate Tectonic

Lithosphereis the rigid outermost shell of a

planet-on Earth, the crust and upper mantle, is

broken up into tectonic plates.

There are two types of lithosphere:

Oceanic lithosphere- associated by oceanic crust

Continental lithosphere- associated by continental

crust


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Plate Tectonic

Tectonic plates are

composed of oceanic

lithosphere andthicker continental

lithosphere, each

topped by its own

kind of crust.
http://en.wikipedia.org/wiki/File:Earth-cutaway-schematic-english.svghttp://en.wikipedia.org/wiki/File:Earth-cutaway-schematic-english.svghttp://en.wikipedia.org/wiki/File:Earth-cutaway-schematic-english.svghttp://en.wikipedia.org/wiki/File:Earth-cutaway-schematic-english.svg


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Plate Tectonic

Athenosphere- is the highly viscous,

mechanically weak and ductilely-deforming

region of the upper mantle of the Earth, lying

beneath the lithosphere.

The upper part of the asthenosphere is believed

to be the zone upon which the great rigid and

brittle lithospheric plates of the Earth's crust

move about.


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Plate Tectonic

It flows like a convection current, radiating heat

outward from the Earth's interior


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Plate Tectonic

PANGEA

The theory that the continents are once a whole.


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Plate Tectonic

The Earth have seven or eight major plates andmany minor plates.


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Plate Tectonic

The Earth have seven or eight major platesand many minor plates:

African South American

Antartic Pacific

Eurasian Indo-Australian

North American


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Plate Boundaries

Where plates meet, their relative motion

determines the type of boundary:

convergent, divergent, or transform.

Earthquakes, volcanic activity, mountain-

building, and oceanic trench formationoccur along plate boundaries.


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Plate Boundaries

Types of Plate Boundaries:

Convergent(Destructive) - occur where two platesslide toward each other to form either a subduction

zone (one plate moving underneath the other) or a

continental collision.


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Plate Boundaries


Transform(Conservative)- occur where two

lithospheric plates slide, or perhaps more accurately,

grind past each other along transform faults, whereplates are neither created nor destroyed. The

relative motion of the two plates is either sinistral

(left side toward the observer) or dextral (right side

toward the observer). Transform faults occur across a

spreading center. Strong earthquakes can occur

along fault.


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Plate Boundaries


Plate boundary zones-occur where the effects of the

interactions are unclear, and the boundaries, usually

occurring along a broad belt, are not well defined

and may show various types of movements in

different episodes.


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Plate Boundaries


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Where Earthquakes occur?

Earthquake-A sudden ground motion or

vibration produced by a rapid release of stored-

up energy.

Epicenter-The point on the Earth's surface

located directly above the focus of an

earthquake.

Focus-The location where the earthquake begins.The ground ruptures at this spot, then seismic

waves radiate outward in all directions


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Earthquakes occur repeatedly where faultlines are.

The shaking ortrembling caused by the

sudden release of energy

(also known as a quake

or tremor)


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80% of Earthquakes

occur in the circum-Pacific belt

Pacific Ring of

Fire


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Forces or Stress

Stressis the force per unit area acting on a

plane within a body. Six values arerequired to characterize completely the

stress at a point: three normalcomponents

and three shearcomponents.


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Forces or Stress

Applied

stressescan causerocks tobend andstretch

Eventually

rocks willbreakaway fromoneanother


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Forces or Stress

This

stressescauses the

Faults.


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Faults

Area in which the rocks break and move iscalled a fault

Vibrations produced is called an earthquake


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Faults

Rocks bend until thestrength of the rock

is exceeded


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Faults

Energy is released in

waves that radiate

outward from the

fault.

Energy

Energy


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Faults

The direction ofmovement along the

fault plane determines

the fault type.


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Faults

Types of Faults:

Normal faults

Reverse faults

Strike slip faults


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Faults

Normal faults- the cracks where one block of

rock is sliding downward and away from

another block of rock. These faults usually occur

in areas where a plate is very slowly splittingapart or where two plates are pulling away from

each other. A normal fault is defined by the

hanging wall moving down relative to thefootwall, which is moving up.


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Faults


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Faults

Reverse faultsare cracks formed where one

plate is pushing into another plate. They also

occur where a plate is folding up because it's

being compressed by another plate pushingagainst it. At these faults, one block of rock is

sliding underneath another block or one block is

being pushed up over the other. A reverse faultis defined by the hanging wall moving up

relative to the footwall, which is moving down.


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Faults


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Faults

Strike slip faults

are the cracks between two

plates that are sliding past each other. You can

find these kinds of faults in California. The San

Andreas fault is a strike-slip fault. It's the most

famous California fault and has caused a lot of

powerful earthquakes.


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Faults


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Tectonic Activities

Earthquake Locations and Depths


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Tectonic Activities

Recent Volcanic Activities


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Tectonic Activities

Tsunami

Tsunami are relatively rare events.

They are generated by submarine earthquakes,volcanic collapse, and coastal landslides, which

suddenly displace huge volumes of water

When a tsunami hits a coastline, the effect ismore like a devastating coastal flood than a

single breaking waves


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Tectonic Activities

EPICENTER


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Philippine Fault

The Philippine Fault System is an inter-

related system of faults throughout the

whole of the Philippine Archipelago,

primarily caused by tectonic forces

compressing the Philippines into what

geophysicists call the Philippine Mobile

Belt.


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Philippine Fault

The Philippine Sea Plateor Philippine Plateis a

tectonic plate comprising

oceanic lithosphere that

lies beneath the Philippine

Sea, to the east of the

Philippines. Most segments

of the Philippines,

including northern Luzon,

are part of the PhilippineMobile Belt, which is

geologically and

tectonically separate from

the Philippine Sea Plate.
http://en.wikipedia.org/wiki/File:Philippine_Sea_Plate_br.JPG


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Philippine Fault

Earthquake and Faults

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