WHAT’S INSIDE THE

EARTH? Prepared by:SIR NICKOLE

ORDIALES

SEISMIC ANATOMYWe are used to

seeing x-ray images of our

bones, such an image does not

show skin, blood, veins or even cells, but they

are still there in spite of the x-ray

only imaging bones.

Similarly seismic does not show everything, it

only shows surfaces that

reflect seismic waves.

Most of what we know about the interior has been deduced from seismic wave data rather than direct measurement.

When an earthquake occurs, it sends waves through the earth that reappear at the surface.

The way these waves are modified in their travels through the center of the earth can be used to tell what the interior is like.

P-waves

ACTIVITY TIME!!!!

The nature of the core (type of

material, liquid or solid) can be

studied by seeing how the P-waves

are refracted.The inner, solid core is deduced

from refraction of P-waves due to

their much higher velocity in the

solid than in the liquid

S-waves

ACTIVITY TIME!!!!

Liquids cannot support the side-to-side motions that make S-waves. S-waves disappear upon reaching the outer core.P-waves can travel through both liquids and solids.

The seismic waves that make the image are those produced by our seismic source. These travel from the source down through the earth and are changed by the earth as they go. The speed at which the wave travels depends on the properties of the material it is travelling through. This speed is measured as the seismic velocity. Because each rock is different, its seismic velocity will be different, and it is where the velocity changes that a reflection or refraction will take place.

At depth we can find higher density materials.

Material Typical seismic velocity (m/s)

Air 330Water 1400-1500Sandstone 1400-4300Limestone 5900-6100Clay 1000-2500

Things that affect the velocity at which the seismic wave can travel through a rock may be: (a) degree of compaction, (b)the presence of fluid and (c) the type of fluid.

Such studies show that Earth consists of:1. a rocky crust ~ 100 km thick2. a mantle, denser than the crust, and "plastic" meaning that it can flow. Extends to ~2900 km below the surface3. an outer core that is a liquid iron/nickel mixture4. an inner core that is a solid iron/nickel mixture

Looking outward to the blackness of space, sprinkled with the glory of the universe of lights, I saw majesty - but no welcome. Below was a welcoming planet. There, contained in the thin, moving, incredible fragile shell of the biosphere is everything that is dear to you, all the human drama and comedy. That's where life is; that's where all the good stuff is.

 -Loren Acton, solar physicist and astronaut

TEST YOUR UNDERSTANDING!

I. COMPLETE THE DATA.

EARTH’S LAYER COMPOSITION WHAT HAPPENS TO THE WAVE?

CRUST

MANTLE

OUTER CORE

INNER CORE

II. TRUE OR FALSE1.When an earthquake occurs, it sends waves through the earth that reappear at the surface.2. Liquids can support the side-to-side motions that make S-waves.3. P-waves disappear as it reaches the core.4. P-waves can’t travel in both liquids and solids material.5. As we go deeper to Earth’s interior the density gets higher.

III. EXPLANATION. Explain briefly.

1. What significant finding does the scientist discover by studying 

earthquake waves?

CHECK YOUR UNDERSTANDING!

I. COMPLETE THE DATA.

EARTH’S LAYER COMPOSITION WHAT HAPPENS TO THE WAVE?

CRUSTSOLID ROCK WAVES TRAVEL FASTER 

MANTLEPARTIALLY MOLTEN ROCKS/SEMI-LIQUID 

WAVES SLOW DOWN

OUTER CORELIQUID (MIXTURE OF IRON/NICKEL)

S-WAVES STOP, P-WAVES CONTINUE TO TRAVEL

INNER CORESOLID IRON/NICKEL P-WAVES ARE REFRACTED

II. TRUE OR FALSETRUE 1.When an earthquake occurs, it sends waves through the earth that reappear at the surface. FALSE 2. Liquids can support the side-to-side motions that make S-waves.FALSE 3. P-waves disappear as it reaches the core.FALSE 4. P-waves can’t travel in both liquids and solids material.TRUE 5. As we go deeper to Earth’s interior the density gets higher.

III. EXPLANATION. Explain briefly.

1. What significant finding does the scientist discover by studying earthquake waves?

By studying seismic waves produced during an earthquake scientist are able to understand the composition of the Earth’s interior. They 

find out that the Earth is layered.

TAKE HOME TASK.

1. Research one typhoon that hits our country. Make a report about it. You can cut from newspaper and paste it in a short bond paper or you can browse the internet.

NO DUPLICATION OF TYPHOON!