UNIT 6

Seismic Engineering and disaster

Management

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SYLLABUS

6.1 Introduction of seismic engineering and its

application civil engineering designs

6.2 Features of disasters such as Floods,

Earthquakes, Fires, Epidemics, Gas/radioactive

leaks etc.

6.3 Management and mitigation of above disasters

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6.1 INTRODUCTION OF SEISMIC

ENGINEERING AND ITS

APPLICATION CIVIL ENGINEERING DESIGNS

Earthquake engineering or Seismic

engineering is a branch of engineering that

searches for ways to make structures, such as

buildings and bridges, resistant to earthquake

damage.

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CONT…

Seismic engineers aim to develop building

techniques that will prevent any damage in a

minor quake and avoid serious damage or

collapse in a major shake.

It is the scientific field concerned with protecting

society, the natural environment, and the man-

made environment from earthquakes.

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SEISMOLOGY

Seismology is the scientific study of earthquakes

and the propagation of elastic waves through the

Earth or through other planet-like bodies.

The field also includes studies of earthquake

environmental effects, such as tsunamis as well as

diverse seismic sources such as volcanic, tectonic,

oceanic, atmospheric, and artificial processes .

A related field that uses geology to infer information

regarding past earthquakes is paleoseismology.

A recording of earth motion as a function of time is

called a seismogram.

6.2.1 EARTHQUAKE

Earthquake means sudden movement or

vibrations on external surface of the earth.

Usually associated with faulting or breaking of

rocks

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IT DEPENDS ON….

1 Epicenter of the earthquake.

2 Various types of vibrations and their

frequencies produced during the earthquake.

3 Mearurement of intensiy of the earthquakes

and its scale of measurement.

4 Foreshocks and aftershocks.

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1. EPICENTER OF THE EARTHQUAKE

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A point on the surface of the Earth directly above

the FOCUS of the earthquake.

The point within the Earth from which

earthquake waves originate.

2. VARIOUS TYPES OF VIBRATIONS

AND THEIR FREQUENCIES PRODUCED

DURING THE EARTHQUAKE

The two main types of waves are

1) body waves - travel through the earth's inner

layers

Two types of Body waves:

P Waves- Primary Waves

S Waves – Secondary Waves

2) surface waves- move along the surface of the

planet like ripples on water

R Waves- Rayleigh Waves

L Waves – Love Waves

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3. MEASUREMENT OF INTENSIFY OF THE

EARTHQUAKES AND ITS SCALE OF

MEASUREMENT.

Seismographs : A seismograph, also

sometimes called a seismometer, is an

instrument that measures and records the

seismic waves that move through the earth as

the result of an earthquake.

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Seismometer and seismograph

RICHTER SCALE

The Richter magnitude scale (also Richter

scale) assigns a magnitude number to quantify

the energy released by an earthquake. The

Richter scale, developed in the 1930s, is a base-10

logarithmic scale, which defines magnitude as

the logarithm of the ratio of the amplitude of the

seismic waves to an arbitrary, minor amplitude.

RICHTER SCALE

EFFECTS OF EARTHQUAKES

Richert scale Type of earthquacke Devastativs Effect

Less than 3 Very light tremor Can be detected by

seismometer only

3-5 Very Light to light

tremor

It can be experienced by

people Utensil in

kitchen vibrate and

make noise

5-6 Medium intensity

tremor

It is felt by many people

carcks appears on

building.

6-7 Medium to heavy

earthquakes

Weaker building fells

down

7- and above Devastating

earthquakes

Buliding fell down

people die or injured by

falling debris.

CAUSES OF EARTHQUAKES

Plate tectonic movements

Volcanic activity

Anthroprogenic causes

IMAGES

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6.2.2 FLOOD

A flood is an overflow of water that submerges

land that is usually dry.

The European Union (EU) Floods

Directive defines a flood as a covering by water of

land not normally covered by water.

In the sense of "flowing water", the word may

also be applied to the inflow of the tide.

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CONT…

Flooding may occur as an overflow of water from

water bodies, such as a river, lake, or ocean, in

which the water overtops or breaks levees,

resulting in some of that water escaping its usual

boundaries, or it may occur due to an

accumulation of rainwater on saturated ground

in an areal flood. While the size of a lake or other

body of water will vary with seasonal changes

in precipitation and snow melt, these changes in

size are unlikely to be considered significant

unless they flood property or drown domestic

animals.18

VARIOUS TYPES OF DISASTERS

FLOOD

6.2.3 CYCLONE

A cyclone is caused by atmospheric disturbances

around a low-pressure area and is usually

accompanied by violent storms and severe

weather conditions.

The word Cyclone is derived from a Greek word

cyclos, meaning coiling of snake. Tropical cyclone

is a deep low pressure area wherein the central

pressure falls 6 to 8 hPa (hectopascal) from the

surroundings.

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CONT…

Strong winds spiral around the centre and pick

up speeds of 62 kmph or more. These winds

rotate counter-clockwise in the Northern

Hemisphere and clockwise in the Southern

Hemisphere.

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CYCLONE OR HURRICANE

6.2.4 TSUNAMI

Tsunami, also called seismic sea wave or tidal

wave, catastrophic ocean wave, usually caused

by a submarine earthquake, an underwater or

coastal landslide, or a volcanic eruption. The

term tidal wave is frequently used for such a

wave, but it is a misnomer, for the wave has no

connection with the tides.

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TSUNAMI

TSUNAMI WAVELENGTH

• Long wavelengths (over 100 km)

• Periods longer than 1 hour

6.2.5 TORNADO

• A tornado is a violently

rotating column of air in

contact with the ground

and out from a

cumulonimbus cloud.

• Tornadoes are capable of

inflicting extreme damage.

Tornadoes can be categorized as "weak", "strong", and "violent"; with weak tornadoes often having a thin, rope-like appearance.

About 7 in 10 tornadoes are weak, with rotating wind speeds no greater than about 110 MPH.

The typical strong tornado often has a "classic" funnel-shaped cloud associated with the whirling updraft. Rotating wind speeds vary from 110 to 200 MPH.

CONT…

TORNADO

6.3 DISASTER MANAGEMENT

It is defined as an integrated approach throughappropriate, comprehensive and sustainableprinciples of development at time before, duringand after disaster so that minimum social,environmental and economical damage is done.

DISASTER MANAGEMENT CYCLE

THANK YOU…

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