three worlds to explore look up? (astronomy) look down? (geophysics) look at surface? (geology)

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Three Worlds to Explor e Look Up? (Astronomy) Look Down? (Geophysics) Look at Surface? (Geology)

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Page 1: Three Worlds to Explore Look Up? (Astronomy) Look Down? (Geophysics) Look at Surface? (Geology)

Three Worlds

to Explore

Look Up?(Astronomy)

Look Down?(Geophysics)

Look at Surface?(Geology)

Page 2: Three Worlds to Explore Look Up? (Astronomy) Look Down? (Geophysics) Look at Surface? (Geology)

The Earth’s Interior

Deep wells and boreholes(4 to 12 km)

Page 3: Three Worlds to Explore Look Up? (Astronomy) Look Down? (Geophysics) Look at Surface? (Geology)

The Earth:

What’s it made

of?

Gravity

Seismology

Magnetism

S

N

Heat Flow

Astronomical Observations

Page 4: Three Worlds to Explore Look Up? (Astronomy) Look Down? (Geophysics) Look at Surface? (Geology)

Crust2.6-3.1 gm/cm3

Mantle3.3-5.7 gm/cm3

Outer Core10-12 gm/cm3

Inner Core13-14 gm/cm3

Density of Water1 gm/cm3

Page 5: Three Worlds to Explore Look Up? (Astronomy) Look Down? (Geophysics) Look at Surface? (Geology)

The primary “tool” for investigating the physical properties of the Earth’s interior is seismology.

Seismology

Page 6: Three Worlds to Explore Look Up? (Astronomy) Look Down? (Geophysics) Look at Surface? (Geology)

What is a Seismic Wave?

• Seismic waves are vibrations that travel through the Earth carrying the energy released during an earthquake.

• Seismic waves travel outward in all directions, like ripples in a pond.

Epicenter

Seismic Waves

Page 7: Three Worlds to Explore Look Up? (Astronomy) Look Down? (Geophysics) Look at Surface? (Geology)

Seismology = The study of seismic waves.

Seismograph = Instrument that records seismic waves.

Seismogram = The record of ground motion that is produced by a seismograph.

Page 8: Three Worlds to Explore Look Up? (Astronomy) Look Down? (Geophysics) Look at Surface? (Geology)
Page 9: Three Worlds to Explore Look Up? (Astronomy) Look Down? (Geophysics) Look at Surface? (Geology)
Page 10: Three Worlds to Explore Look Up? (Astronomy) Look Down? (Geophysics) Look at Surface? (Geology)
Page 11: Three Worlds to Explore Look Up? (Astronomy) Look Down? (Geophysics) Look at Surface? (Geology)

Two main groups of seismic waves.

Body waves travel through the Earth’s interior.

Surface waves are guided by the outer layers of the Earth.

Page 12: Three Worlds to Explore Look Up? (Astronomy) Look Down? (Geophysics) Look at Surface? (Geology)

Two types of body waves.

P-waves = Primary Waves = first arrival

S-waves = Secondary Waves = second arrival

Page 13: Three Worlds to Explore Look Up? (Astronomy) Look Down? (Geophysics) Look at Surface? (Geology)

P-waves and S- waves are distinguished from each other by the way they propagate through the Earth.

P-waves push (compress) and pull (dilate) rocks in the direction the wave is traveling.

Page 14: Three Worlds to Explore Look Up? (Astronomy) Look Down? (Geophysics) Look at Surface? (Geology)
Page 15: Three Worlds to Explore Look Up? (Astronomy) Look Down? (Geophysics) Look at Surface? (Geology)

S-waves “shake” the material at right angles to their direction of travel.

Page 16: Three Worlds to Explore Look Up? (Astronomy) Look Down? (Geophysics) Look at Surface? (Geology)
Page 17: Three Worlds to Explore Look Up? (Astronomy) Look Down? (Geophysics) Look at Surface? (Geology)
Page 18: Three Worlds to Explore Look Up? (Astronomy) Look Down? (Geophysics) Look at Surface? (Geology)

Slide courtesy of Seth Stein

Page 19: Three Worlds to Explore Look Up? (Astronomy) Look Down? (Geophysics) Look at Surface? (Geology)

Slide courtesy of Seth Stein

Page 20: Three Worlds to Explore Look Up? (Astronomy) Look Down? (Geophysics) Look at Surface? (Geology)

Slide courtesy of Seth Stein

Page 21: Three Worlds to Explore Look Up? (Astronomy) Look Down? (Geophysics) Look at Surface? (Geology)

Slide courtesy of Seth Stein

Page 22: Three Worlds to Explore Look Up? (Astronomy) Look Down? (Geophysics) Look at Surface? (Geology)

P-waves can travel through solids, liquids, and gases because matter in all three of these states resists being compressed and will elastically spring back once the force is removed.

S-waves can only travel through solids, because fluids do not resist shearing motion. So, fluids do not transmit S-waves.

Page 23: Three Worlds to Explore Look Up? (Astronomy) Look Down? (Geophysics) Look at Surface? (Geology)

The Earth’s Interior

Deep wells and boreholes(4 to 12 km)

Page 24: Three Worlds to Explore Look Up? (Astronomy) Look Down? (Geophysics) Look at Surface? (Geology)
Page 25: Three Worlds to Explore Look Up? (Astronomy) Look Down? (Geophysics) Look at Surface? (Geology)

Two main groups of seismic waves.

Body waves travel through the Earth’s interior.

Surface waves are guided by the outer layers of the Earth.

Page 26: Three Worlds to Explore Look Up? (Astronomy) Look Down? (Geophysics) Look at Surface? (Geology)

Two types of body waves.

P-waves = Primary Waves = first arrival

S-waves = Secondary Waves = second arrival

Page 27: Three Worlds to Explore Look Up? (Astronomy) Look Down? (Geophysics) Look at Surface? (Geology)
Page 28: Three Worlds to Explore Look Up? (Astronomy) Look Down? (Geophysics) Look at Surface? (Geology)

Two types of surface waves.

Rayleigh waves: Discovered by Lord Rayleigh (1887).

Love waves: Discovered by A.E.H. Love (1911).

Page 29: Three Worlds to Explore Look Up? (Astronomy) Look Down? (Geophysics) Look at Surface? (Geology)
Page 30: Three Worlds to Explore Look Up? (Astronomy) Look Down? (Geophysics) Look at Surface? (Geology)

Slide courtesy of Seth Stein

monthsweeksdayshoursminutes

Page 31: Three Worlds to Explore Look Up? (Astronomy) Look Down? (Geophysics) Look at Surface? (Geology)

Slide courtesy of Seth Stein

monthsweeksdayshoursminutes

Page 32: Three Worlds to Explore Look Up? (Astronomy) Look Down? (Geophysics) Look at Surface? (Geology)

Data from station MBWA (Marble Bar, Western Australia)

last updated at Thu 10/30/03 12:53 GMT

Page 33: Three Worlds to Explore Look Up? (Astronomy) Look Down? (Geophysics) Look at Surface? (Geology)

Magnitude 7.1 Earthquake in Taiwan - December 26, 2006

Page 34: Three Worlds to Explore Look Up? (Astronomy) Look Down? (Geophysics) Look at Surface? (Geology)

Magnitude 7.1 Earthquake in Taiwan - December 26, 2006

Page 35: Three Worlds to Explore Look Up? (Astronomy) Look Down? (Geophysics) Look at Surface? (Geology)
Page 36: Three Worlds to Explore Look Up? (Astronomy) Look Down? (Geophysics) Look at Surface? (Geology)
Page 37: Three Worlds to Explore Look Up? (Astronomy) Look Down? (Geophysics) Look at Surface? (Geology)

Slide courtesy of Seth Stein

Radial

Transverse

Vertical

Rayleigh

Love

Rayleigh

Page 38: Three Worlds to Explore Look Up? (Astronomy) Look Down? (Geophysics) Look at Surface? (Geology)

In the case of surface waves, the ground motion is concentrated near the surface of the Earth, and the wave motion is similar to that of water waves in the ocean.

Page 39: Three Worlds to Explore Look Up? (Astronomy) Look Down? (Geophysics) Look at Surface? (Geology)

In the case of water waves, a particle of water (or a toy boat) at the surface moves in a circular pattern, but stays at the same location.

At greater depth, the water particles also move in circles, but the circles are smaller.

Page 40: Three Worlds to Explore Look Up? (Astronomy) Look Down? (Geophysics) Look at Surface? (Geology)

Rayleigh wave motion is similar to water wave motion, except that for Rayleigh waves, the circles are “retrograde”.

<>

Page 41: Three Worlds to Explore Look Up? (Astronomy) Look Down? (Geophysics) Look at Surface? (Geology)
Page 42: Three Worlds to Explore Look Up? (Astronomy) Look Down? (Geophysics) Look at Surface? (Geology)

Love waves have side-to-side ground motion, similar to S-waves, except that the ground motion decays with depth in a manner similar to Rayleigh waves and water waves.

Page 43: Three Worlds to Explore Look Up? (Astronomy) Look Down? (Geophysics) Look at Surface? (Geology)
Page 44: Three Worlds to Explore Look Up? (Astronomy) Look Down? (Geophysics) Look at Surface? (Geology)
Page 45: Three Worlds to Explore Look Up? (Astronomy) Look Down? (Geophysics) Look at Surface? (Geology)

Differences in density and other physical properties affect the velocity of seismic waves.

Granite (and Average Continental Crust)

6.0 km/sec

3.5 km/sec

2.5 km/sec

3.0 km/sec

Page 46: Three Worlds to Explore Look Up? (Astronomy) Look Down? (Geophysics) Look at Surface? (Geology)

Continental Crust:P-wave Velocity = 6 km/sec“Granite”

Oceanic Crust:P-wave Velocity = 7 km/sec“Basalt”

Page 47: Three Worlds to Explore Look Up? (Astronomy) Look Down? (Geophysics) Look at Surface? (Geology)

Crust2.6-3.1 gm/cm3

Mantle3.3-5.7 gm/cm3

Outer Core10-12 gm/cm3

Inner Core13-14 gm/cm3

Density of Water1 gm/cm3

Page 48: Three Worlds to Explore Look Up? (Astronomy) Look Down? (Geophysics) Look at Surface? (Geology)

Crust6-7 km/sec

Mantle8-13 km/sec

Outer Core8-10 km/sec

Inner Core10-11 km/sec

P-wave Velocitie

s

Page 49: Three Worlds to Explore Look Up? (Astronomy) Look Down? (Geophysics) Look at Surface? (Geology)