Activity 1

FAULTS and EARTHQUAKES

DIRECTIONS: Use the Diagrams and Word bank to fill in the paragraph below.

Diagram 1 Diagram 2

WORD BANK

Fault Focus
Strike -Slip Fault Epicenter
Normal Fault Footwall
Reverse Fault Hanging Wall
Oblique Fault Seismic Waves

As a result of plate motion, the accumulated stress on the rocks of the lithosphere may cause great warps or folds in
rock layers. Where rock is strained beyond its limit, it will fracture, and the rock mass on either side will move
abruptly.
Most _______________ occur on faults. A _______________ is a thin zone of crushed rock between two blocks of
rock, and can be any length, from centimeters to thousands of kilometers. When an earthquake occurs on a fault,
the rock on one side of the fault slips with respect to the other. The fault surface can be vertical, horizontal, or at
some angle to the surface of the earth. Faults are categorized into three general groups based on the sense of slip or
movement.
Where the crust is being pulled apart, _______________ forms, in which the overlying (hanging-wall) block
moves down with respect to the lower (foot wall) block. 
Where the crust is being compressed, _______________ forms, in which the _______________ block moves up
and over the _______________ block – reverse slip on a gently inclined plane is referred to as thrust faulting. 
Crustal blocks may also move horizontally or sideways past each other. This ______________ movement is
described as sinistral when the far side moves to the left, and dextral, when the far side moves to the right. 
An _______________ involves various combinations of these basic movements, which included both reverse and
dextral movement.
All earthquakes start beneath Earth’s surface. The _______________ of an earthquake is the point underground
where rocks first begin to move. Seismic waves travel outward from the earthquake’s focus. The
_______________ is the point on Earth’s surface directly above the focus.
In general, if two earthquakes of equal strength have the same epicenter, the one with the shallower focus causes
more damage. _______________ from a deep-focus earthquake lose more of their energy as they travel farther up
to Earth’s surface.

Answer the following questions:

1. What is an earthquake?
2. What is fault?
3. What happens to a fault when an earthquake occurs?
4. How do faults move?
5. How movement along faults generate earthquake?
6. What is the relationship between faults and earthquakes?
 Activity 2
WHERE DOES AN EARTH QUAKE?

Directions: Read the concept background and study the map to answer the questions below.

Plate boundaries are found at the edge of the Earth’s crustal plates. There three types, collisional (convergent),
spreading ridges (divergent) and transform (conservative). The three boundaries are characterized by their distinct
motions.

Most earthquakes occur near plate boundaries, where stresses between adjacent plates can build up. When
suddenly released, a sudden shock occurs in the crust – what we experience as an earthquake.
At spreading ridges, earthquakes are shallow, and occur along the axis of spreading. Earthquakes at spreading
ridges tend to be smaller than magnitude 8.
At transforms, earthquakes are shallow, running as deep as 25 km. Transforms tend to have earthquakes smaller
than magnitude 8.5.
At collisional boundaries, earthquakes are found in several settings ranging from the very near surface to several
hundred kilometers depth. The coldness of the subducting plate permits brittle failure down to as much as 700 km.
Collision boundaries host Earth's largest quakes, with some events at subduction zones in Alaska and Chile having
exceeded magnitude 9.

This map shows the plates of the Earth’s crust. The yellow dots show where earthquakes have happened over the
last 40 years.

Answer the following questions:

1. What do you notice about where Earthquakes happen?

2. Why do you think this is?
3. How far is Ireland trom the nearest earthquake zone?
4. Do you think there are more earthquakes in areas where the Earth’s plates are moving towards each other, or
where the plates are moving apart? Why do you think this is?
 Activity 3
TSUNAMI ALERT

Directions: Read the concept background and study the diagrams to answer the questions below.

A Tsunami is a series of sea waves commonly generated by under-the-sea earthquakes and whose heights could
be greater than 5 meters. It is erroneously called tidal waves and sometimes mistakenly associated with storm
surges.
Tsunamis can occur when the earthquake is shallow-seated and strong enough to displace parts of the seabed and
disturb the mass of water over it.
The most destructive tsunamis are generated from large, shallow earthquakes with an epicenter or fault line
near or on the ocean floor. These usually occur in regions of the earth characterized by tectonic subduction along
tectonic plate boundaries.
The term tsunami from the Japanese and means "Big wave in the port". The term was coined by fishermen who
returned to their ports in the evening after their villages and cities had been devastated by a giant wave although
they had not seen any waves on the open sea.
Tsunamis arise from the sudden displacement of gigantic water masses due to earthquakes on the sea bed, Volcanic
eruption above and under water, landslides or meteorite impacts. About 86 % of all Tsunamis result from so-called
seaquakes.
In order for a tsunami caused by seaquakes to occur, three things have to be happen:
1: The Earthquake must measure at least 7,0 on the Richter scale. Only from this intensity upwards is there enough
energy released to rapidly displace enough water to create the tsunami.
2: The sea bed must be lifted or lowered by the earthquake. If the sea bed is displaced side wards, no tsunami will
occur .
3: The epicenter of the earthquake must be near to the earth's surface.

Diagram 1 Diagram 2 Diagram 3

Answer the following questions:

1. What is Tsunami?___________________________________________________________________________
____________________________________________________________________________________________
2. How it is generated? _________________________________________________________________________
____________________________________________________________________________________________
3. What cause tsunami and how it is form? ________________________________________________________
____________________________________________________________________________________________
4. Name a few trenches that you observe or see in diagram 3 ___________________________________________
____________________________________________________________________________________________
5. Determine the areas in the Philippines that are prone to tsunami. ______________________________________
____________________________________________________________________________________________
6. Why is it important to know the location of Philippines trenches and tsunami prone areas in the country? ______
____________________________________________________________________________________________
____________________________________________________________________________________________
2. How it can be of help when we know that our place is included in the tsunami prone area? _________________
____________________________________________________________________________________________
 Activity 4
ACTIVE AND INACTIVE FAULT

Directions: Read the concept background and study the diagrams to answer the questions below.

Faults may be classified according to their level of activity.

Active faults are structure along which we expect displacement to occur. By definition, since a shallow earthquake
is a process that produces displacement across a fault, all shallow earthquakes occur on active faults.
Inactive faults are structures that we can identify, but which do not have earthquake. As you can imagine, because
of the complexity of earthquake activity, judging a fault to be inactive can be tricky, but often we can measure the
last time substantial offset occurred across a fault. If a fault has been inactive for millions of years, it's certainly
safe to call it inactive.
Reactivated faults form when movement along formerly inactive faults can help to alleviate strain within the crust
or upper mantle.
The Philippine Fault System is a major inter-related system of faults throughout the whole of the Philippine
Archipelago.
The Philippine Fault Zone (PFZ) extends 1200 km across the Philippine archipelago behind the convergent
boundary of the Philippine Trench and the subduction of the Philippine Sea Plate. This left-lateral strike-slip fault
extends NW-SE (N30 – 40 W) accommodating the lateral oblique motion of the subducting Philippine Sea Plate
with respect to the Philippine Trench. It extends from Davao Gulf in the south, bisects the Caraga region at the
Agusan River basin, crosses to Leyte and Masbate islands, and traverses Quezon province in eastern Luzon before
passing through Nueva Ecija up to the Ilocos region in northwest Luzon. The northern and southern extensions of
the PFZ are characterized by branching faults due to brittle terminations. These horsetail faults are indicative of the
lateral propagation and further development of the PFZ. The fault's current activity can be observed in Holocene
sandstone outcrops on the Mati and Davao Oriental islands. The fault experiences a slip rate of approximately 2-
2.5 cm/year.

DIAGRAM 1

DIAGRAM 2 DIAGRAM 3

Answer the following questions:

1. Name some at least 10 active faults in the Philippines.
2. What is an active Fault and how does it differ in inactive fault?
3. Will there be a possibility that an inactive fault may be active again? What is reactivated fault?
4. Is there a place in the Philippines where there is no traces of fault?
5. Would it mean that it is safe to live in that place?
6. Why is it important to locate the active fault near in our area?
7. If we found out that an active fault is near to our place, what should we do?
8. Is your place located along the fault lines?
9. What's your plan if you are aware that the fault will move any time or if an earthquake will hit your place and
destroy your home?
 Activity 5
SEISMIC WAVES

Directions: Read the concept background and study the diagrams to answer the questions below.

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
Types of Seismic Waves
A. BODY WAVES Traveling through the interior of the earth, body waves arrive before the surface waves emitted
by an earthquake. These waves are of a higher frequency than surface waves.
B. SURFACE WAVES Travelling only through the crust, surface waves are of a lower frequency than body
waves, and are easily distinguished on a seismogram as a result. Though they arrive after body waves, it is surface
waves that are almost enitrely responsible for the damage and destruction associated with earthquakes. This
damage and the strength of the surface waves are reduced in deeper earthquakes.

Diagram 1
Diagram 2
Diagram 3

Diagram 4

Identify the type of wave that can be

found on specific areas in the earth’s crust.

Answer the following questions:

1. What is a seismic wave?
2. How it is recorded?
3. How many types of seismic waves do you see?
4. How do they differ?
5.How does P waves differ from S waves?
6. How does Love waves differ from Reyleigh Waves?
7. How do scientists visualize the earth’s interior?
Activity 6
 SEISMIC WAVES

Directions: Read the concept background and study the diagrams to answer the questions below.

A seismometer detects the vibrations caused by an earthquake which are plotted by a seismograph.
The earthquake and its impact is measured either by using the Mercalli scale or the Richter Scale. The two scales,
however, each have different applications as well as measurement techniques.
The Mercalli scale has been in existence longer dating back to the 19th century. Its name comes from the
modifications made to it in the 1890s by an Italian volcanologist, Giuseppe Mercalli.
The Richter scale was developed in 1935 by Charles Richter, along with his associate, Beno Gutenberg, and today
it is the commonly used scale in earthquake measurement.
Magnitude and Intensity measure different characteristics of earthquakes. Magnitude measures the energy released
at the source of the earthquake. Magnitude is determined from measurements on seismographs. Intensity measures
the strength of shaking produced by the earthquake at a certain location. Intensity is determined from effects on
people, human structures, and the natural environment.
The PHIVOLCS Earthquake Intensity Scale (PEIS) is a seismic scale used and developed by the Philippine
Institute of Volcanology and Seismology (PHILVOLCS) to measure the intensity of an earthquake.
It was developed as a response to the 1990 Luzon earthquake. PHILVOLCS cites seismic scale specifically
developed for the Philippine setting, the different geography of each country and other "geological considerations"
led to the development of PEIS. The scale measures the effect of an earthquake on a given area based on its relative
effect to people, structures and objects in the surroundings.
The PEIS was adopted in the Philippines in 1996 replacing the Rossi-Forel scale.

Diagram 1 – Table Comparing Diagram 2 – Table Comparing

Magnitude and Intensity Richter and Mercalli Scale
Diagram 3 Table of Philvolcs Earthquake Intensity Scale (PEIS)

Answer the following questions:

1. How can we tell the strength of an earthquake?
2. How do we measure Earthquake?
3. What are other ways to determine the strength of an earthquake?
4. Which scale measures Magnitude? Which measure intensity?
5. How does magnitude different from intensity?
6. How does Richters, Mercalli and Philvocs Measures Earthquake Intensity and Magnitude?
 Activity 7
UNDESRTANDING TYPHOON

Directions: Read the concept background and study the diagrams to answer the questions below.

The Philippines is a tropical country geographically located along the Pacific region near the Equator. The country
is surrounded by large bodies of water and facing the Pacific Ocean where 60% of the world's typhoons are made
It lies along the west pacific basin, which is considered the world’s busiest typhoon belt, bounded on the west by
the West Philippine Sea, on the east by the Pacific ocean, on the north of Bashi channel, and on the south by the
Sulu and Celebes Seas.
Approximately twenty tropical cyclones enter the Philippine area of responsibility yearly, an area which
incorporates parts of the Pacific Ocean, South China Sea and the Philippine Archipelago (with the exception of
Tawi-Tawi province). Among these cyclones, ten will be typhoons, with five having the potential to be destructive
ones. In the Philippine languages, tropical cyclones are generally called bagyo.
Typhoons can hit the Philippines any time of year, with the months of June to September being most active, with
August being the most active individual month and May the least active. Typhoons move east to west across the
country, heading north as they go.
Tropical cyclones entering the Philippine Area of Responsibility are given a local name by the Philippine
Atmospheric, Geophysical and Astronomical Services Administration (PAGASA), which also raises public storm
signal warnings as deemed necessary.
Typhoon is one of the most destructive and life-threatening natural calamities in the Philippines. It is a very big
mass of whirling moist air formed in warm seas. It brings heavy rains, strong winds, coastal floods and dangerous
waves. Typhoons are also known as storm, hurricanes, and tropical cyclones.

Answer the following questions:

1. Where is the Philippines located?

2. What surrounds the Philippines?
3. How do the location and surrounding bodies affect the Philippines?
4. What do you commonly experience during typhoons?
 Activity 8
TYPHOON? HURRICANE? CYCLONE? WHAT’S THE DIFFERENCE ?

Directions: Read the concept background and study the diagrams to answer the questions below.

Hurricanes, cyclones, and typhoons are all the same weather phenomenon; we just use different names for these
storms in different places. In the Atlantic and Northeast Pacific, the term “hurricane” is used. The same type of
disturbance in the Northwest Pacific is called a “typhoon” and “cyclones” occur in the South Pacific and Indian
Ocean.
A tropical cyclone is a generic term used by meteorologists to describe a rotating, organized system of clouds and
thunderstorms that originates over tropical or subtropical waters and has closed, low-level circulation. Once a
tropical cyclone reaches maximum sustained winds of 74 miles per hour or higher, it is then classified as
a hurricane, typhoon, or cyclone depending upon where the storm originates in the world.
Tropical cyclones rotate counterclockwise in the Northern Hemisphere.
Diagram of Weather Phenomenon and their names around the world.

Answer the following questions:

1. What is a hurricane, typhoon, or tropical cyclone?
2. Where Do Hurricanes, Typhoons, and Cyclones Form?
3. Are they the same or different?
4. How do they differ?

Complete the Table

Name of weather phenomenon Where it come from? How does it move?

1.

2.

3.

Activity 9
TYPHOON CATEGORY
Directions: Read the concept background and study the diagrams to answer the questions below.
Tropical cyclones are ranked on one of five tropical cyclone intensity scales, according to their maximum
sustained winds and which tropical cyclone basin(s) they are located in. Only a few scales of classifications are
used officially by the meteorological agencies monitoring the tropical cyclones, but some alternative scales also
exist, such as accumulated cyclone energy, the Power Dissipation Index, the Integrated Kinetic Energy Index, and
the Hurricane Severity Index.
Storms that form around the United States in either the North Atlantic or the Northeast Pacific are classified using
the Saffir-Simpson Hurricane Scale, which uses the Category 1-5 rankings. In the Western Pacific, the US
military's Joint Typhoon Warning Center (JTWC) uses a scale that includes the Super Typhoon label. The
Japanese Meteorological Agency (JMA) and the Regional Specialized Meteorological Center (RSMC) in Tokyo
also have their own scale. 
The Saffir-Simpson Hurricane Scale ranks strong storms from
Category 1 to Category 5, with Cat 5 being reserved for the real
monsters.  Technically this scale only applies to Hurricanes affecting
North America. It is based on wind speed measurements averaged over
a 1-minute period at that same height. 
Tropical cyclone that develops within the North Indian Ocean between
100°E and 45°E is monitored by the India Meteorological Department
(IMD, RSMC New Delhi).Within the region a tropical cyclone is
defined as being a non-frontal synoptic scale cyclone, that originates
over tropical or subtropical waters with organized convection and a
definite cyclonic surface wind circulation.

Any tropical cyclones that occur within the Northern Hemisphere between
the anti-meridian and 100°E, are officially monitored by the Japan
Meteorological Agency (JMA, RSMC Tokyo) The JMA scale used by the
RSMC in Tokyo is completely different from the other two scales. The
Japanese use these classifications: Tropical Depression, Tropical Storm,
Severe Tropical Storm, Typhoon, Very Strong Typhoon, and Violent
Typhoon.
Tropical cyclones entering the Philippine Area of Responsibility are
classified based on wind intensity by the Philippine Atmospheric,
Geophysical and Astronomical Services Administration (PAGASA), which
also raises public storm signal warnings as deemed necessary.

Answer the following questions:

1. How are tropical cyclones

classified?
2. What is/are the basis of
classifying tropical cyclone?
3. What agencies monitored the
movement of tropical cyclone
from the different part of the
world?
4. In the Philippines, how is the tropical cyclone classified?
5. What is/are the role/roles of PAGASA?