TRAINING ON EARTH AND SPACE SCIENCE

19-28 July 2016 - Marbella Suites Hotel, Jl. Sentra Dago Pakar, Bandung

The Earth Interior

in Plate Tectonics Perspective

Asep Saepuloh, Dr. Eng.

Assistant Professor
Faculty of Earth Sciences and Technology
Bandung Institute of Technology (ITB)
Email: saepuloh@gc.itb.ac.id
http://www.asepsaepuloh.com/
Fig. 10.7
 Before we get going, let’s review…

• Plate
• Lithosphere
• Asthenosphere
• Radioactive Decay
• Convection
The Layers of the Earth

© Copyright 2006. M. J. Krech. All rights reserved.

The Four Layers
The Earth is composed of four
different layers. The crust is
the layer that you live on, and
it is the most widely studied
and understood. The mantle
is much hotter and has the
ability to flow. The outer
core and inner core are
even hotter with pressures so
great you would be squeezed
into a ball smaller than a
marble if you were able to go
to the center of the Earth!
The Crust
The Earth's Crust is like
the skin of an apple. It is
very thin in comparison to
the other three layers. The
crust is only about 3-5
miles (8 kilometers) thick
under the oceans (oceanic
crust) and about 25 miles
(32 kilometers) thick
under the continents
(continental crust).
 The Lithospheric Plates

The crust of the Earth is broken into many pieces called

plates. The plates "float" on the soft, semi-rigid
asthenosphere.
The Asthenosphere

The asthenosphere is the semi-

rigid part of the middle mantle
that flows like hot asphalt under a
heavy
weight.
 The Lithosphere
The crust and the upper layer of the mantle
together make up a zone of rigid, brittle rock
called the Lithosphere.
 The Crust

The crust is composed of two rocks. The continental

crust is mostly granite. The oceanic crust is basalt. Basalt
is much denser than the granite. Because of this the less
dense continents ride on the denser oceanic plates.
The Mantle
The Mantle is the
largest layer of the Earth.
The middle mantle is
composed of very hot
dense rock that flows like
asphalt under a heavy
weight. The movement of
the middle mantle
(asthenosphere) is the
reason that the crustal
plates of the Earth move.
Convection Currents

The middle mantle "flows"

because of convection
currents. Convection
currents are caused by the
very hot material at the
deepest part of the mantle
rising, then cooling and
sinking again --repeating
this cycle over and over.
Convection Currents

The next time you heat anything like

soup or water in a pan you can watch
the convection currents move in
the liquid. When the convection
currents flow in the asthenosphere
they also move the crust. The crust
gets a free ride with these currents,
like the cork in this illustration.

Safety Caution: Don’t get your face

too close to the boiling water!
The Outer Core

The core of the Earth

is like a ball of very
hot metals. The
outer core is so
hot that the metals
in it are all in the
liquid state. The
outer core is
composed of the
melted metals of
nickel and iron.
The Inner Core

The inner core of the

Earth has
temperatures and
pressures so great that
the metals are
squeezed together
and are not able to
move about like a
liquid, but are forced
to vibrate in place like
a solid.
 EXCERCISE

Find a pair or trio and answer

this question:

Have we ever seen

part of the Mantle?
Explain.

© Copyright 2006. M. J. Krech. All rights reserved.

Exploring the interior with seismic waves

 Paths of seismic waves

 Wave bending (refraction)
 Shadow zones (P and S)
 Reflection at internal boundaries
P-wave
paths
S-wave
paths
P- and
S-wave
paths
from an
earthquake
P-, S-, and surface wave
paths: from focus to seismograph
P-, S-, and surface waves
recorded on a seismograph
Mantle structure
Mantle structure
Mantle structure
Teori Pengapungan Benua (1912)
Alfred Wegener (1880-1930)

The main features of plate tectonics

are:
•The Earth's surface is covered by a
series of crustal plates.
•The ocean floors are continually
moving, spreading from the center,
sinking at the edges, and being
regenerated.
•Convection currents beneath the plates move the crustal
plates in different directions.
•The source of heat driving the convection currents is
radioactivity deep in the Earths mantle.
Penelitian Gravity Vening Meinesz
ahli Geofisika Belanda 1940 - 1959
• Menemukan anomali gaya berat di Palung
Sumatra (pantai barat Sumatera)

• 1962 (Harry Hess) : arus konveksi dari

penelitian di dasar Samudera Atalantik 
• Sea Floor Spreading
 A Combination of Two Ideas
• Continental Drift
• Sea-Floor Spreading
 Plate Tectonic Environments
• Extensional (Divergent)
• Convergent (Compressional)
• Transform
ekstensional konvergen

transform
EQ 1906

EQ 1984
Pinatubo Kanaga
1990-an

St. Helen 1980

Krakatau 1883 Merapi 2006

Perkembangan Tektonik Kepulauan Indonesia sejak 50 juta th.yl.