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Earthquake - a sudden and rapid shaking of Seismic Belt - narrow geographic zone on
the ground due to passage of vibrations the earth's surface along which most
beneath caused by transient disturbance of earthquake activity occurs.
elastic or gravitational equilibrium of rocks
Three main seismic belts in the world
- - measured using observations from
1. Circum-Pacific seismic belt
seismometers.
2. Alpine-Himalayan seismic belt
Seismology- Scientific study of earthquakes 3. Ridge seismic belt.
seismic waves are recorded on instruments The point on a fault within earth's crust where
called Seismograph the fracturing begins and most slippage
occurs is called the FOCUS or hypocenter.
Time, location, magnitude of an earthquake
can be determined from the data recorded by The point on the earth's surface directly
seismograph stations above the focus is the Epicenter.
Shifting tectonic plates - send vibrations or Earthquakes originate within the earth.
shock waves through the ground
Two types of body waves
Shock waves - grow fainter farther from the
1. P- waves
epicenter, and destruction on Earth's surface
2. S-waves
is less severe.
P waves (Primary waves) - the fastest
- travel outward from the focus
seismic waves and are the first to be detected
Richter magniture scale was developed in once an earthquake has occurred.
1935 by Charles F. Richter
- travel through the earth's interior many
micro earthquakes - earthquakes with times faster than the speed of a jet
magnitude of about 2.0 or less airplane.
- predominantly compressional waves.
Great earthquakes - have magnitudes of 8.0
As it passes, material compresses in
or higher
the same direction the wave is moving,
Natural Causes of earthquake and then extends back to its original
thickness once the wave has passed.
1. Tectonic Movement
2. . Volcanic Activity The speed at which P-waves travel through
3. Pressure of gases in the interior material is determined by:
4. Landslides and avalanches
▪ rigidity
5. Faulting and folding in the rock beds
▪ compressibility
are responsible for causing minor
▪ density
earthquakes
Man-made earthquakes- The impounding of 1. Rigidity - how strongly the material resists
large quantities of water behind dams being bent sideways and is able to
disturbs the crustal balance. straighten itself out once the shearing force
has passed - the more rigid, the faster the
- The shock waves through rocks set up P-waves
by the underground testing of Atom 2. Compressibility - how much the material
bombs or hydrogen bombs may be can be compressed into a smaller volume
severe to cause earthquake. and then recover its previous volume once
the compressing force has passed; the
more compressible, the faster the P-waves
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3. Density - how much mass the material magnitude of an earthquake - is a number

contains in a unit of volume; the greater the that allows earthquakes to be compared with
density, the slower the P-waves each other in terms of their relative power.
S waves (secondary waves) - the second- earthquake magnitudes were calculated
fastest seismic waves and the second type to based on a method first developed by Charles
be detected once an earthquake has occurred. Richter a seismologist based in California.
▪ shear waves as They move by material Richter used seismograms of earthquakes
flexing or deforming sideways that occurred in the San Andreas fault zone
(shearing) from the direction of wave to calibrate his magnitude scale.
travel, and then returning to the original
Richter scale has been replaced by the
shape once the wave passes.
moment magnitude scale
Elastic rebound theory - description of how
moment magnitude scale - broadly similar to
earthquakes occur
the Richter scale, but it takes more factors into
▪ stresses build on both sides if a fault, account, including the total area of the fault
causing the rocks to deform plastically that moves during the earthquake, and how
(Time 2). When the stresses become much it moves.
too great, the rocks break and end up in
Earthquake intensity - is a ranking based on
a different location. This releases the
the observed effects of an earthquake in each
builtup energy and creates an
particular place.
earthquake.
❖ shallow earthquakes - it causes the most The most commonly used earthquake
damage because the focus is near where intensity scale is the Modified Mercalli
people live. earthquake intensity scale
▪ Earthquakes that are less than 70 km
deep Magnitude, Modified Mercalli Intensity,
Description
Most earthquakes occur in the crust or
upper lithosphere less than 70 km (50
miles) deep in the earth.
❖ Intermediate-depth earthquakes -
Earthquakes that occur between 70 and
300 km deep
❖ Deep earthquakes - Earthquakes 300-700
km deep
80% of all earthquakes strike around the
Pacific Ocean basin because it is lined with Ground shaking - is caused by seismic
convergent and transform boundaries. waves During a significant earthquake, a
particular location, and any building at that
15% in the Mediterranean-Asiatic Belt where location, will be shaken by body waves (P- and
convergence is causing the Indian plate to run S-) and surface waves , and can shear or
into the Eurasian Plate. move a building in a different way, sometimes
5% are scattered around other plate simultaneously.
boundaries or are intraplate earthquakes Earthquake Hazards
Seismogram - which is a graphic record of the 1. Ground Shaking
seismic waves, viewed either on paper or on a 2. Permanent Ground Displacement
computer monitor 3. Earth Rupture
4. Landslides and Avalanches
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5. Liquefaction on people, human structures, and the natural

6. Fires environment.
7. Tsunamis
Permanent Ground Displacement - the
ground may permanently shift to a new
position up, down, or sideways (up to 10 or
EARTHQUAKE INTENSIRY SCALE
more m, 30 or 40 ft, in extreme cases). This
1. Scarcely Perceptible change in the location of the ground, which
2. Slightly felt also tilts the ground, may cause disruption of
3. Weak roads and utilities and, in coastal cities,
4. Moderately strong submergence or emergence of harbor
5. Strong facilities.
6. Very strong
Earth Rupture - some rupturing of the earth’s
7. Destructive
surface takes place along the fault trace. This
8. Very destructive
produces a fault scarp, which may have up to
9. Devastating
several m (up to 10 ft or more) of vertical
10. Completely devastating
displacement.
Landslides and Avalanches - On steep
Tsunami - is a set of waves in the ocean (or a slopes and in mountainous areas, large
large lake) with an extremely long wavelength, earthquakes can set off many landslides,
typically over 100 km long. Typically over 100 rockfalls, or avalanches. These can damage
km long. Tsunamis move at many 100s of km buildings, towns, or roads in the path of the
per hour in deep water. Tsunamis can be set landslides.
off by violent volcanic eruptions originating just
Liquefaction - If fine- or medium-grained,
below sea level,
unconsolidated sediments are saturated with
Mercalli Intensity Scale - Earthquakes are groundwater, the shaking that occurs during
described in terms of what nearby residents an earthquake may cause the sediment grains
felt and the damage that was done to nearby to lose contact with each other and become
structures. suspended in the water, temporarily turning
what was solid ground into liquid ground.
Richter magnitude scale - Developed in
1935 by Charles Richter, this scale uses a Fires are a secondary rather than a primary
seismometer to measure the magnitude of the effect of earthquakes. Broken electrical wires
largest jolt of energy released by an and natural gas pipes commonly set off fires
earthquake. during earthquakes. To compound the
problem, the water supply may also be
Moment magnitude scale - Measures the disrupted by earthquake damage, making it is
total energy released by an earthquake. impossible to put the fire out with water from
Moment magnitude is calculated from the area fire hydrants.
of the fault that is ruptured and the distance the
ground moved along the fault
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
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Stress - the force applied to an object. They do not return to their original shape. If
the rocks experience more stress, they may
▪ force applied to a rock and may cause
undergo more folding or even fracture
deformation.
▪ the force per unit area that is placed on Three types of folds
a rock
1. Monocline
Four types of stresses act on materials. 2. Anticline
3. Syncline
1. confining stress - A deeply buried rock
is pushed down by the weight of all the MONOCLINE - is a simple bend in the rock layers
material above it. Since the rock cannot so that they are no longer horizontal
move, it cannot deform.
ANTICLINE - is a fold that arches upward. The
2. Compression squeezes rocks
rocks dip away from the center of the fold. The oldest
together, causing rocks to fold or
rocks are at the center of an anticline and the
fracture. CONVERGENT PLATE
youngest are draped over them.
3. Tension - Rocks that are pulled apart
are under tension. Rocks under ▪ Dome - When rocks arch upward to form a
tension lengthen or break apart. circular structure
DIVERGENT PLATE
SYNCLINE - e is a fold that bends downward. The
4. Shear - When forces are parallel but
youngest rocks are at the center and the oldest are at
moving in opposite directions.
the outside.
TRANSFORM PLATE
▪ Basin - When rocks bend downward in a
When stress causes a material to change
circular structure
shape, it has undergone strain or
deformation. FAULTS
Rocks have three possible responses to JOINT - If there is no movement on either
increasing stress side of a fracture.
▪ elastic deformation: the rock returns FAULT - If the blocks of rock on one or both
to its original shape when the stress is sides of a fracture move.
removed.
SLIP - the distance rocks move along a fault.
▪ plastic deformation: the rock does
Can be up or down the fault plane.
not return to its original shape when
the stress is removed. Faults lie at an angle to the horizontal surface
▪ fracture: the rock breaks of the Earth is called the fault’s dip.
Sedimentary rocks are formed with the DIP-SLIP FAULT - the fault’s dip is inclined
oldest layers on the bottom and the youngest relative to the horizontal.
on top.
There are two types of dip-slip faults.
▪ Sedimentary rock layers that are not
horizontal are deformed ▪ In normal faults, the hanging wall
drops down relative to the footwall.
Deformation produces geologic structures ▪ In reverse faults, the footwall drops
such as folds, joints, and faults that are down relative to the hanging wall.
caused by stresses
THRUST FAULT - a type of reverse fault in
FOLDS which the fault plane angle is nearly
horizontal. Rocks can slip many miles along
FOLDS - Rocks deforming plastically under
thrust faults.
compressive stresses crumple into folds.
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STRIKE-SLIP FAULT - is a dip-slip fault in 3 different types of strain

which the dip of the fault plane is vertical. It
result from shear stresses. ▪ elastic strain
▪ ductile strain
Two converging continental plates smash
upwards to create mountain ranges. Stresses ▪ fracture.
from this uplift cause folds, reverse faults, and Elastic strain is reversible. Rock that has
thrust faults, which allow the crust to rise undergone only elastic strain will go back
upwards. to its original shape if the stress is
basin-and-range - is alternating mountains released.
and valleys. When tensional stresses pull crust Ductile strain is irreversible. A rock that
apart, it breaks into blocks that slide up and has undergone ductile strain will remain
drop down along normal faults. deformed even if the stress stops. Another
horsts - some blocks are uplifted to form term for ductile strain is plastic
ranges deformation.

grabens - d some are down-dropped to form Fracture is also called rupture. A rock that
basins has ruptured has abruptly broken into
distinct pieces.
stress - forces that push, pull, or twist it.
The factors that determine whether a rock
Strain - any change in volume or shape. is ductile or brittle include:
Lithostatic pressure - also called hydrostatic ▪ Composition
pressure. It comes from the weight of rock ▪ Temperature
above a given point in the earth ▪ Lithostatic pressure
▪ Strain rate
▪ .All rocks in the earth experience a
uniform stress at all times The following correlations can be made
between types of stress in the earth, and the
3 types of directed (non-uniform) stress
type of fault that is likely to result:
▪ Tension (pushing together) o Tension leads to normal faults.
▪ Compression (pulling apart) o Compression leads to reverse or thrust
▪ shear. (twisting or rotating) faults.
o Horizontal shear leads to strike-slip
Tension - pulls rock apart in opposite
fault
directions. The tensional (also called
extensional) forces pull away from each other. Geologic structures such as faults and folds
are the architecture of the earth’s crust.
Compression - pushes rocks together. The
compressional forces push towards each Brittle - If rocks tend to break
other.
Ductile- If rocks tend to bend without breaking
Shear - pushes one side of a body of rock in
one direction, and the opposite side of the elastic behavior - If a rock bends but is able
body of rock in the opposite direction. The to return to its original position when the stress
shear forces are pushing in opposite ways. is released
plastic behavior. - If a rock bends and stays
bent after stress is released
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basic types of folds

• Anticlines – down folds
• Synclines – up folds
anticline appears as parallel beds of the same
rock type that dip away from the center of the
fold.
syncline appears as a set of parallel beds that
dip toward the center.
Plunge direction - the direction in which the
axis of the fold tilts down into the earth.
Basin – a bowl-like depression in the strata.
Dome – a bulge in strata.
Faults - is a planar surface within the earth,
along which rocks have broken and slid.
Hanging wall – rocks above a fault
Footwall – rocks beneath a fault
detachment fault - s a particular kind of
normal fault that generally dips at a low angle.
reverse or thrust fault - the hanging wall has
moved up relative to the footwall
Strike-slip faults - are steep or vertical faults
along which the rocks on either side have
moved horizontally in opposite directions.
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HYDROLOGICAL CYCLE
Mining means withdrawing or removing
something from within the Earth.
Groundwater is found within the Earth and is
our second largest store of freshwater.

97% - sea water

3% - freshwater

Reservoir - storage location for water such as

an ocean, glacier, pond, or even the
atmosphere.
Residence Time - The amount of time a Water budgets provide a means for
molecule stays in a reservoir evaluating availability and sustainability of a
water supply.
Water – simply 2 atoms of hydrogen and 1
atom of oxygen bonded together. A water budget states that the difference
between the rates of water flowing into and out
▪ Water expands when it freezes, has
of an accounting unit is balanced by a change
high surface tension (because of the
in water storage:
polar nature of the molecules, they tend
to stick together), and others. Flow In – Flow Out = Change In Storage
Hydrologic Cycle - movement of water Storage is the retention of water by parts of
around Earth’s surface. the system that can include surface
impoundments (like lakes), soil moisture, and
The three phases of water are:
groundwater aquifers.
1. solid (ice or snow)
EFFECTS OF CLIMATE CHANGE TO
2. liquid (water)
WATER RESOURCES
3. gas (water vapor)
• increased evaporation rates
➢ The Sun’s heat provides energy to
• higher proportion of precipitation
evaporate water from the Earth’s surface received as rain
(oceans, lakes, etc.).
➢ Transpiration - Plants also lose water to • earlier and shorter runoff seasons
the air. • increased water temperatures
➢ The water vapor eventually condenses, • decreased water quality in both inland
forming tiny droplets in clouds and coastal areas.
➢ When the clouds meet cool air over land,
Fluvial systems are dominated by rivers and
precipitation (rain, sleet, or snow) is
streams.
triggered, and water returns to the land (or
sea). Stream erosion may be the most important
➢ Some of the underground water is trapped geomorphic agent.
between rock or clay layers; this is called
Fluvial processes sculpt the landscape,
groundwater.
eroding landforms, transporting sediment, and
➢ But most of the water flows downhill as depositing it to create new landforms.
runoff (above ground or underground),
eventually returning to the seas as slightly
salty water.
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RIVER BASIN – means the area of land from is large enough, there could be a permanent
which all surface run-off flows through a water course fed by surface run-off and
sequence of streams, rivers and, possibly groundwater, thereby forming a river basin
lakes into the sea at a single river mouth,
IMPORTANCE OF RIVER BASINS
estuary or delta.
River basins have an important
▪ to be considered as a whole for
environmental and social role, supplying
resource management purposes
freshwater, regulating water flow and quality,
▪ s are comprised of sub-basins, which
protecting from natural hazards such as floods
are catchments where a water course
and landslides, and enabling the conservation
flows into a certain point of a larger
of biodiversity. They also have an important
basin, such as a lake or a confluence of
role for human development, such as in
rivers.
energy generation (such as hydropower) and
PARTS OF A RIVER BASIN providing recreational opportunities
❖ Upper Basin -Headwaters
❖ Mid-basin -Low gradient valleys and
flood plains
❖ Lower Basin -Depositional Zone
Upper basin: is the area where we find the
source of the main river, in mountain and
hillside areas.
Middle basin: it is where we find the river
valley, where usually the river runs in zigzag
through the land.
Lower basin: the low-lying area where rivers
slow down and deposit the sediment they have
collected, forming plains.
TYPES OF RIVER BASIN
1. Exorheic or open basins: their water
drains into the sea or the ocean.
2. Endorheic or closed basins: they are
basins that drain into lakes, ponds or
salt flats, with no outlet to the sea.
3. Arheic basins: basins where water
evaporates or infiltrates into the soil
before forming a drainage system. They
are common in desert areas such as
the Sahara.
How does a river basin form?
As part of the water cycle, rainfall runs off the
land surface and is collected into the small
channels of ephemeral streams. A portion of
the rainfall evaporates or infiltrates into the
land, and the remainder runs off down the
gradient of the land surface. If the catchment