What feasible we might

go through if we are
situated near the
Pacific Ring of Fire?
 What is an
earthquake?
Earthquakes are ground movements
that occur when blocks of rock in Earth
move suddenly and release energy.

The energy is released as seismic waves

that cause the ground to move.
The place within
Earth where the first
motion occurs is
called the focus.

The place on Earth’s

surface above the
focus is called the
epicenter.
What causes earthquakes?
Most earthquakes occur near a tectonic
plate boundary, which is where two or
more tectonic plates meet.
The release of energy that accompanies
the movement of rock along a fault is
what causes an earthquake.
How to measure earthquake?
Earthquakes are recorded by a seismographic
network. Each seismic station in the network
measures the movement of the ground at that
site. The slip of one block of rock over another
in an earthquake releases energy that makes
the ground vibrate.
An instrument that
measures and
records details
of earthquakes,
such as force and
duration.
How to Find the Epicenter of an Earthquake
Scientists use triangulation to find the
epicenter of an earthquake. When seismic
data is collected from at least three different
locations, it can be used to determine the
epicenter by where it intersects. Every
earthquake is recorded on numerous
seismographs located in different directions.
Each seismograph records the times
when the first (P waves) and second (S
waves) seismic waves arrive. From that
information, scientists can determine
how fast the waves are traveling.
Knowing this helps them calculate the
distance from the epicenter to each
seismograph.
 Distance – Time Graph
A travel time curve is a graph of the time that it
takes for seismic waves to travel from the
epicenter of an earthquake to seismograph
stations at varying distances away. The velocity
of seismic waves through different materials
yield information about Earth's deep interior.
How do scientists use
a distance time graph
to study of
earthquakes?
The time difference between the P-
and S-waves tells us the distance the
earthquake is from the seismometer.
If we calculate the S minus P time to
determine distance from the
seismometer at three stations, we
can work out where the epicenter of
the earthquake is.
Sample #1
Sample #2
Plate Tectonic Theory
The theory of plate tectonics states
that the Earth’s solid outer crust, the
lithosphere, is separated into plates
that move over the asthenosphere,
the molten upper portion of the
mantle.
 Plate Tectonics is a theory
which suggests that Earth’s
crust is made up of plates that
interact with various ways, thus
producing earthquakes,
mountains, volcanoes and other
geologic features.
Tectonic Plates are rigid
sections of the lithosphere that
move as a unit. Most of the
Earth is covered by EIGHT
major plates and another
SEVEN are minor plates.
https://en.wikipedia.org/wiki/Plate_tectonics#/media/File:Plates_tect2_
 Basic Plate Tectonic Concepts
Earth’s crust and the uppermost layer of the
mantle are composed of rigid units called plates.
The movement of these plates is small, in the
order of millimeters per year.
Large-scale geological activities occur on or near
plate boundaries.
Areas farther from plate boundaries are less
prone to earthquakes.
Basic Plate Tectonic Concepts

The Philippine Sea plate,

which is oceanic, moves
northwestward, ranging
from as fast as 102
mm/year down around
54 mm/year.

https://en.wikipedia.org/wiki/Philippine_Sea_Plate#/
media/File:PhilippinePlate.png
Properties
Thickness OCEANIC CONTINENTAL
7-10 35-40
(km)
Density 3.0 g/cm³ 2.7 g/cm³
Rocks Basalt Granite
Age Younger Older
Under land
Found in Under oceans
continents
Major Key Concepts
The volcanoes, earthquake’s
epicenter, and major mountain
belts are distributed in close
proximity of the borders of the
tectonic plates. Once tectonic
plates moved in any possible
motion, it could create changes
leading to geologic features and
events.
Major Key Concepts
Most of the active volcanoes
nowadays are found in the so called
“Pacific Ring of Fire” which is
practically the border of the Pacific
Tectonic Plate.
Pacific Ring of Fire
• Argentina • Kiribati
• Belize • Malaysia
• Bolivia • Mexico
• Brazil • New Zealand
• Brunei • Nicaragua
• Canada • Palau
• Colombia • Papua New Guinea
• Chile • Panama
• Costa Rica • Peru
• Ecuador • Philippines
• East Timor • Russia
• El Salvador • Samoa
• Micronesia • Singapore
• Fiji • Solomon Islands
• Guatemala • Tonga
• Honduras • Tuvalu
• Indonesia • United States
• Japan https://www.quora.com/What-countries-are-in-the-Pacific-Ring-
of-Fire
Major Key Concepts
The earthquake epicenters are not
found only in a specific place, but
they are found everywhere where
there's a border between two or more
tectonic plates. It doesn't matter if
they collide, move away from each
other, or subduct, the earthquakes will
Major Key Concepts
The major mountain belts are
found in places where tectonic
plates of the same density
collide, so instead some of
them go and be subducted,
they push against each other
and lift the area up.
Remember:
Places on earth where most of the
earthquakes originated or some
mountains and volcanoes were formed
mark the boundaries of each
lithospheric plate.
Each plate is slowly moving relative to
each other, causing geologic events to
happen along their boundaries.
Remember:
Plates are large pieces of the upper few
hundred kilometers of Earth that move
as a single unit as it floats above the
mantle.
As plates interact along their margins,
important geological processes take
place,
such as the formation of mountain
belts, earthquakes, and volcanoes.
Types of Waves
Compression wave
Transverse Wave
Seismic Wave
Body Waves
Primary or p-wave
Compression wave
Secondary or s-wave
Transverse wave
Surface
Love wave
Rayleigh wave
Seismic Wave
Seismic waves are the waves of energy
caused by the sudden breaking of rock within
the earth or an explosion. They are the
energy that travels through the earth and is
recorded on seismographs.
There are several different kinds of seismic
waves, and they all move in different ways.
The two main types of waves are body waves
and surface waves.
Body Waves
P Waves (compression wave)
The first kind of body wave is the P wave or
primary wave. This is the fastest kind of seismic
wave. The P wave can move through solid rock
and fluids, like water or the liquid layers of the
earth. It pushes and pulls the rock it moves
through just like sound waves push and pull the
air.
Stop and Think
Have you ever heard a big clap of
thunder and heard the windows rattle
at the same time?
The windows rattle because the sound
waves were pushing and pulling on the
window glass much like P waves push
and pull on rock. Sometimes animals can
hear the P waves of an earthquake.
Usually we only feel the bump and rattle
of these waves.
Body Waves
S wave (transverse wave)
The second type of body wave is the S wave or
secondary wave, which is the second wave you
feel in an earthquake. An S wave is slower than a P
wave and can only move through solid rock. This
wave moves rock up and down, or side-to-side.
Which leads scientists to believe that
Earth's inner core is solid?
What leads scientists to believe that Earth's
inner core is solid is the observation that
seismic waves (waves that travel through the
Earth's interior) move at different speeds as
they pass through different layers of the
Earth. The inner core is made of solid iron
and nickel due to its high pressure and
temperature.
Surface Waves
Love Waves
The first kind of surface wave is called a Love
wave, named after A.E.H. Love, a British
mathematician who worked out the mathematical
model for this kind of wave in 1911. It's the fastest
surface wave and moves the ground from side-to-
side. Most damaging type among surface waves.
Surface Waves
Rayleigh Waves
The other kind of surface wave is the Rayleigh wave, named
for John William Strutt, Lord Rayleigh, who mathematically
predicted the existence of this kind of wave in 1885. A
Rayleigh wave rolls along the ground just like a wave rolls
across a lake or an ocean. Because it rolls, it moves the
ground up and down, and side-to-side in the same direction
that the wave is moving. Most of the shaking felt from an
earthquake is due to the Rayleigh wave, which can be much
larger than the other waves.
 In geology the word "discontinuity" is used for a
surface at which seismic waves change velocity.

The various discontinuities of the earth are as follows.

1. Conrad Discontinuity: The Conrad Discontinuity
separates the upper and lower crust. (Victor
Conrad)
2. Mohorovicic Discontinuity: This is the transition
zone between the crust and the mantle.
3. Repetti Discontinuity: This separates the upper
mantle from the lower mantle. (William C. Repetti)
4. Gutenberg Discontinuity: This is the transition
zone between the lower mantle and the outer core.
5. Lehmann Discontinuity: This is the layer
separating the outer core from the inner core.
This discontinuity was
identified by Weichert
Gutenberg in 1912 at a depth
of 2900 kilometers beneath
the earth's surface. The
velocity of seismic waves
changes abruptly in this zone.
At this depth, the velocity of
the P wave diminishes, and
the S wave vanishes
completely.
In 1929, while examining
seismograph data collected after a
large earthquake in New Zealand,
Lehmann noticed that seismographs
stationed in the Russian cities of
Swerdlowsk (Yekaterinburg) and
Irkutsk collected seismic waves with
amplitudes that were higher than
she had expected. She also
discovered that some waves
traveling away from the
earthquake’s focus appeared to have
been “bent.”
LOVE THE MOMENT
AND THE ENERGY
OF THAT MOMENT
WILL SPREAD
BEYOND ALL
BOUNDARIES.