REPORT

EATHQUAKE

JEET ANIL RAUT

R. NO: 09
ABCM- 07
VIVA SCHOOL OF ARCHITECTURE
INDEX
FORMATION OF EARTH …1

INTERNAL STRUCTURE OF EARTH …2

INTRODUCTION TO EARTHQUAKE …4

CAUSES OF EARTHQUAKE …6

PLATE TECTONIC MOVEMNETS …6

CLASSIFICATION OF FAULTS …7

MEASUREMENTS OF EARTHQUAKE …8

SEISMIC HAZARDS DUE TO EARTHQUAKE …9

TERMS USED IN EARTHQUAKES …10
…12
CAUSES/SOURCES OF EARTHQUAKE
EFFECTS OF AN EARTHQUAKE …15

WHAT TO DO DURING AN EARTHQUAKE …16

PRINCIPLES OF EARTHQUAKE RESISTING DESIGN …20

CODES TO DESIGN EARTHQUAKE RESISTANT

…21
STRUCTURES

SEISMIC ZONES OF INDIA …23

UNDERSTANDING SEISMOGRAPH AND THE

RICHTER SCALE …24

STATIC AND DYNAMIC ANALYSIS OF …27

STRUCTURE
 THE FORMATION OF EARTH

• Billions of years ago, Earth and the rest of our solar system were entirely
unrecognizable, existing only as a vast cloud of dust and gas.
• That dust cloud was eventually disrupted by a unique event that even the
world's greatest scientists are still unable to explain.
• This disturbance set off a chain of events that finally led in the
creation of life as we know it.
• One generally believed idea among scientists is that the dust
cloud came together as a result of disturbance caused by a
supernova explosion caused by the collapse of a distant star. As
a result, a solar nebula, a revolving disc of gas and dust, formed.
• As the gravity in the cloud's center grew over time, hydrogen
atoms began to travel more quickly and violently. The protons in the
hydrogen began to fuse, producing helium and releasing a massive
amount of energy.
• This culminated in the formation of the sun, the star that acts as the
focal point of our solar system, some 4.6 billion years ago.

Fig.01. FORMATION OF EARTH

https://scitechdaily.com/images/Scientists-Probe-Earths-Core.jpg

01
 INTERNAL STRUCTURE OF EARTH
The Earth's interior is divided into several layers, each with distinct
characteristics. These layers are differentiated based on their composition,
physical properties, and behavior.

CRUST:
The crust is the Earth's outermost layer and is relatively thin compared to the
other layers. It consists of two main types: the continental crust and the oceanic
crust. The continental crust is thicker and less dense, composed mainly of
rocks like granite. The oceanic crust is thinner and denser, primarily made up
of rocks like basalt. The crust is where we live and where most geological
activity, like earthquakes and volcanoes, occurs.

MANTLE:
Beneath the crust lies the mantle, a thick layer of semi-solid rock that extends to a
depth of about 2,900 kilometers (1,800 miles). The mantle is divided into the
upper mantle and the lower mantle. The upper mantle is partially molten and
behaves like a plastic material over long periods. Convection currents in the
mantle drive the movement of tectonic plates on the Earth's surface.

OUTER CORE:
Below the mantle is the outer core, which extends from a depth of about 2,900
kilometers (1,800 miles) to about 5,150
kilometers (3,200 miles).

Fig.02. INTERNAL STRUCTURE OF EARTH

https://scitechdaily.com/images/Scientists-Probe-Earths-Core.jpg

02
The outer core is composed mainly of liquid iron and nickel. It's responsible for
generating the Earth's magnetic field through a process called the geodynamo,
where the movement of molten metal creates electrical currents that produce
the magnetic field.

INNER CORE:
At the Earth's center, from a depth of about 5,150 kilometers (3,200 miles) to
the center at about 6,371 kilometers (3,959 miles), is the inner core. The
inner core is extremely hot and under tremendous pressure, which keeps it
in a solid state despite the high temperature. It is composed mostly of iron and
nickel, similar to the outer core, but it's solid due to the extreme pressure.

In summary, the Earth's internal structure consists of the crust (divided into
continental and oceanic), the mantle (with upper and lower sections), the outer
core (liquid), and the inner core (solid). This layered structure plays a crucial
role in the planet's geological processes, including plate tectonics, volcanic
activity, and the generation of the Earth's magnetic field.

03
 INTRODUCTION TO EARTHQUAKE

Fig.03. INTRODUCTION TO EARTHQUAKE

https://www.grunge.com/img/gallery/the-truth-about-the-largest-earthquake-in-u-s-history/intro-1597239152.jpg

• An earthquake, also known as a quake, tremor, or temblor, is a natural

phenomenon caused by the sudden release of an enormous amount of
energy stored within the Earth's crust.
• This energy release occurs due to the movement of tectonic plates, which
are large sections of the Earth's crust that float on the semi-fluid layer
beneath.
• When the stress along these plates reaches a critical point, it overcomes
the friction holding them together, resulting in rapid movement.
• This movement generates seismic waves that propagate outward from
the point of origin, known as the focus or hypocenter.
• In cases where the epicenter of a larger earthquake is located beneath
the seabed in the ocean or sea, the sudden vertical displacement of the
underwater crust can trigger a tsunami.
• Tsunamis are large oceanic waves caused by the displacement of
a significant volume of water.

04
 CAUSES OF EARTHQUAKE

NATURAL CAUSE :

• Earthquakes are caused by slow-moving processes within the ground.

Earth was hot when it originated and has been cooling ever since (near
the surface, the temperature rises by around 30 degrees Celsius for every
kilometer into the earth).The cooling of the earth causes pieces of the
earth to move, and this movement is referred to as an
earthquake.

CAUSED BY HUMANS :

• DAMS AND RESERVOIRS :

It's only water, yet water is dense. Dam-created reservoirs of water have a
long history of causing earthquakes. The 2008 earthquake in Sichuan,
China, that killed almost 70,000 people, was one of the most destructive
in recent memory, and some scientists believe it was caused by the
adjacent Zipingpu Dam.

• GROUNDWATER EXTRACTION :
Water extraction from the earth, which causes the water table to fall, might
also destabilize an existing fault. • Geothermal power plants: As geothermal
field operations have expanded, so has seismic activity.

• FRACKING AND INJECTION WELLS :

When fracking fluid waste is poured underground into deep wells. The
fluid might seep out and lubricate flaws, making them slip easier.

• SKYSCRAPERS :
It's all about applying too much pressure on the soft sedimentary
rock beneath. This tension is caused by the additional steel and concrete
employed to make the building strong enough to withstand earthquakes.

05
 PLATE TECTONIC MOVEMENTS

Fig.04. TECTONIC MOVEMENTS

https://www.grunge.com/img/gallery/the-truth-about-the-largest-earthquake-in-u-s-history/intro-1597239152.jpg

• TRANSFORM BOUNDARIES:
At transform boundaries, tectonic plates slide past each other horizontally.
This movement causes earthquakes along fault lines. Transform boundaries
connect segments of divergent and convergent boundaries. The San Andreas
Fault in California is a well-known transform boundary, where the Pacific Plate
and the North American Plate are sliding past each other.

• DIVERGENT BOUNDARIES:
At divergent boundaries, tectonic plates move away from each other. This
movement is often associated with the formation of new oceanic crust. As
plates separate, magma from the mantle rises to fill the gap, solidifies upon
contact with seawater, and forms underwater mountain ranges called mid-
ocean ridges. The most famous example of a divergent boundary is the Mid-
Atlantic Ridge.

• CONVERGENT BOUNDARIES:
Convergent boundaries occur when tectonic plates move toward each
other. This movement leads to subduction (one plate going beneath another)
or continental collision. There are three types of convergent boundaries:
1. Oceanic-Continental Convergence
2. Oceanic-Oceanic Convergence:
3. Continental-Continental Convergence

06
 CLASSIFICATIONS OF FAULTS
A fault is a fracture or break in the Earth's crust along which there has been
movement of the rock on either side. This movement is caused by tectonic
forces, and it can be vertical, horizontal, or at an angle. Faults are categorized
based on the direction of the movement relative to the angle of the fault
plane.

NORMAL FAULTS:
Normal faults occur when tensional forces pull rocks apart. The hanging wall
(the rock layer above the fault plane) moves downward relative to the
footwall (the rock layer below the fault plane). Normal faults are
common in areas with extensional tectonic settings, such as divergent
boundaries.

REVERSE FAULTS (Thrust faults):

Reverse faults are caused by compressional forces that push rocks together.
The hanging wall moves upward relative to the footwall. If the fault plane is
nearly horizontal, it's called a thrust fault. Reverse faults are found in regions
with convergent tectonic settings.

STRIKE-SLIP FAULTS:
In strike-slip faults, the rocks move horizontally past each other with minimal
vertical movement. This type of movement is typical along transform
boundaries, where tectonic plates slide past each other. The San Andreas
Fault is a well-known example of a strike-slip fault.

07
 MEASUREMENTS IN EARTHQUAKE

Earthquakes are measured using various instruments and scales to quantify their
size, impact, and intensity. Here are some key measurements used in earthquake
studies:
• MAGNITUDE:
Earthquake magnitude is a measure of the energy released at the earthquake's
source. It quantifies the size of the seismic waves generated by the
earthquake. The Richter scale, Moment Magnitude Scale (Mw), and other
regional magnitude scales are used to express earthquake magnitude. The
Richter scale is a logarithmic scale, meaning each whole number
increase represents a tenfold increase in amplitude of the seismic waves and
approximately 31.6times more energy released.

• INTENSITY:
Earthquake intensity measures the effects of an earthquake on the Earth's
surface and the built environment. The Modified Mercalli Intensity (MMI)
scale is commonly used to describe the level of shaking and the impact on
structures, people, and the landscape. The MMI scale ranges from I (not felt)
to XII (total destruction).

• SEISMIC WAVES:
Seismic waves generated by an earthquake are recorded by seismographs
(seismometers). The time it takes for seismic waves to travel from the
earthquake's source to a seismograph station is used to determine the earthquake's
location.

• EPICENTER:
The epicenter is the point on the Earth's surface directly above the earthquake's
focus (the point within the Earth where the earthquake originates). The
distance from the epicenter to a seismograph station, combined with the
time it took for the seismic waves to arrive, helps locate the earthquake's source.

• HYPOCENTER:
Also known as the focus, the hypocenter is the actual point where the
earthquake begins within the Earth's crust. Its depth is an important parameter, as
earthquakes at different depths can have varying impacts on the surface.

08
 SEISMIC HAZARDS DUE TO EARTHQUAKE

SURFACE RUPTURE:
In areas where the Earth's crust is under high stress, earthquakes can cause the
ground to rupture along fault lines. Surface rupture can damage infrastructure
directly, disrupt roads and railways, and impact underground utilities.

LIQUEFACTION:
In loose, water-saturated soils, the shaking during an earthquake can cause the
ground to behave like a liquid temporarily. This phenomenon, known as
liquefaction, can result in buildings sinking into the ground, tilting, or toppling over.

BUILDING AND INFRASTRUCTURE COLLAPSE:

Poorly constructed buildings and infrastructure are vulnerable to the forces of an
earthquake. Structures that are not designed to withstand seismic forces can
collapse, resulting in casualties and destruction.

IMPACT ON ECONOMY AND SOCIETY:

Seismic hazards can lead to disruption of transportation,
communication, and utilities, causing economic losses and
hindering emergency response efforts. Long-term impacts include displacement of
populations, loss of livelihoods, and disruptions to essential services.

TECTONIC UPLIFT OR SUBSIDENCE:

In some cases, earthquakes can cause a portion of the Earth's crust to rise or sink.
This can lead to flooding in low-lying areas or changes in coastal geography.

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 TERMS USED IN EARTHQUAKES
MAGNITUDE OF EARTHQUAKE

• It is a quantitative measure of the actual size of the earthquake.

• Professor Charles Richter noticed that some distance, seismograms
of larger earthquakes have bigger wave amplitude than those of smaller
earthquakes.
• For a given earthquake, seismograms at farther distances have smaller
wave amplitude than those at close distances.

INTENSITY OF EARTHQUAKE

• It is a qualitative measure of the actual shaking at a location during an

earthquake and is assigned as Roman capital numerical.
• The distribution of intensity at different places during an earthquake
is shown graphically using isoseismal, line-joining places with equal
seismic intensity

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SEISMIC WAVES

• Seismic wave, vibration generated by an earthquake, explosion, or similar

energetic source and propagated within the Earth or along its surface.
• Earthquakes generate four principal types of elastic waves; two, known as
body waves, travel within the Earth, whereas the other two, called surface
waves, travel along its surface.
• Seismographs record the amplitude and frequency of seismic waves and
yield information about the Earth and its subsurface structure.
• Artificially generated seismic waves recorded during seismic surveys are
used to collect data in oil and gas prospecting and engineering.

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 CAUSES/SOURCES OF EARTHQUAKE

TECTONIC
EARTHQUAKE:-
moving tectonic
plates on the
surface of the earth
provide mechanisms
for a great deal of
the seismic activity
of the world.

DILATANCY IN CRUSTAL ROCK:- Crust thickness varies du to litho-static

pressure exceeding the strength of th rock. The rock flows like plastic material
because tem and pressure is very high. As this layer expands an moves, this
causes ground motion.

EXPLOSIONS:- Ground shaking may produced by the underground detonation

of chemical or nuclear devices. Underground nuclear explosions fired during the
past several decades at several test sites around the world have produced
substantial artificial earthquakes.

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VOLCANIC EARTHQUAKE:-

VOLCANIC EXPLOSION

SHALLOW EARTHQUAKE ARISING FROM MAGMA

TECTONIC EARTHQUAKE
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COLLAPSE EARTHQUAKE:-
These are small earthquake occurs in a region of underground caverns and
mines. The immediate cause of ground shaking is the sudden collapse of the roof
of the mine.

LARGE RESERVOIRS INDUCED EARTHQUAKE:-

It has been seen that the earthquake might be triggered by impounding surface
water. Most of the dams above 100m in height have at least some history of
earthquakes.

IMPACT EARTHQUAKES:-
These are very rare earthquakes and occur due to meteorite strike

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 EFFECTS OF AN EARTHQUAKE :

Earthquakes can have a wide range of effects, varying in severity depending on

factors such as the quake’s magnitude, the depth of its epicentre and the local
geology. Here are some of the primary effects caused by earthquakes:

Ground Shaking:
When an earthquake occurs, the release of energy creates seismic waves that cause
the ground to shake. The intensity of the shaking can vary depending on factors
such as the magnitude of the earthquake, the distance from the epicentre and the
local geology. Areas closer to the epicentre usually experience more intense
shaking, which can significantly damage structures and infrastructure.

Damage to Man-Made Structures:

One of the most noticeable effects of an earthquake is the damage it can cause to
buildings, bridges, roads and other man-made structures. The shaking can lead to
structural failure, collapse and extensive damage, especially if the buildings are not
designed or constructed to withstand seismic activity. The severity of the damage
depends on factors such as the quality of construction, adherence to building codes
and proximity to the epicentre.

Fires and Hazardous Chemical Spills:

Earthquakes can trigger secondary hazards, such as fires and hazardous material
spills. The violent shaking can rupture gas pipelines, damage electrical systems and
disrupt infrastructure, leading to the ignition of fires. Additionally, earthquakes can
cause the release of hazardous chemicals stored in industrial facilities, posing risks
to human health and the environment. These secondary effects can further
exacerbate the impact of an earthquake and complicate rescue and recovery efforts.

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Landslides and Avalanches:
In areas with steep slopes or unstable terrain, earthquakes can trigger landslides
and avalanches. The shaking can destabilize slopes, causing rocks, soil and debris
to slide downhill. Landslides can damage structures, block roads and even bury
entire communities, leading to additional casualties and hindering rescue and relief
operations access.

Tsunamis:
Underwater earthquakes can generate tsunamis, particularly those occurring along
tectonic plate boundaries. These massive ocean waves can travel long distances,
reaching coastal areas and causing devastating flooding. Tsunamis pose a
significant threat to coastal communities and can result in widespread destruction
and loss of life.

Understanding the potential effects of earthquakes is crucial for implementing

appropriate mitigation measures and developing effective disaster response plans.
It is important to note that these are just some of the effects that earthquakes can
have. The severity and extent of these effects depend on various factors, including
the earthquake’s characteristics, the impacted area’s location and the affected
communities’ preparedness and resilience.
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 WHAT TO DO DURING AN EARTHQUAKE?
When it comes to earthquakes, being prepared can make all the difference. Here
are some essential steps to take before the disaster strikes:

BEFORE THE EARTHQUAKE :

Make Connections Flexible

Ensure that gas lines and appliances are properly installed with flexible
connections. This helps prevent gas leaks and reduces the risk of fire hazards
during an earthquake.

Create an Earthquake Readiness Plan

Develop a well-thought-out plan that includes identifying a shelter area in your
home. Stock up on essential supplies such as canned food, a well-stocked first aid
kit, ample water, dust masks, goggles, firefighting equipment, a flashlight and a
working battery-operated radio. These provisions will prove invaluable in the
event of an earthquake.

Consult Architects and Structural Engineers

Building sturdy structures is vital for minimizing earthquake damage and ensuring
the safety of occupants. If you reside in an earthquake-prone area, it’s crucial to
consult with architects and structural engineers before constructing buildings. They
can guide you in implementing the necessary measures and adhering to regulations
set by the disaster management committee.

Spread Awareness
Share the knowledge and importance of earthquake preparedness with your friends
and family. By educating those around you, you contribute to creating a safer
community.
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DURING THE EARTHQUAKE

When an earthquake strikes, quick thinking and appropriate actions can save
lives. Here are some important guidelines to follow:

Stay Indoors
Remain indoors until the shaking stops and it is officially announced that it is
safe to exit. Taking cover beneath a sturdy table or bed can provide vital
protection against falling objects.

Avoid Hazardous Areas

Steer clear of bookcases, heavy furniture and appliances that may topple over
during the earthquake. Your safety should always be the top priority.

Find a Safe Spot

Seek shelter under a sturdy piece of furniture, such as a table or bed. Hold on to a
post or any other fixture to maintain stability and minimize the risk of injury.

If Outdoors, Move to an Open Area

If you are outside when the earthquake occurs, find a clear spot away from
buildings, trees and power lines. These objects pose a significant danger during
seismic activity.

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After the Earthquake

Once the earthquake subsides, it’s important to proceed with caution and take
the following measures:
Administer First Aid
Attend to individuals with minor injuries using first aid kits. For those with
more severe injuries, it’s essential to wait for professional medical help and
avoid moving them until it is safe.

CPR and Rescue Breathing

If someone is not breathing, administer rescue breathing. If the person has no
pulse, perform CPR (cardiopulmonary resuscitation) until medical assistance
arrives.

Be Mindful of Hazards
Attend any tumbling shelves or falling items and be cautious around damaged
walls made of bricks or other unstable materials. Your safety should be a
priority.

Check Gas and Power Connections

Inspect gas valves for leaks and turn off the main power switch if damage is
possible. Unplug broken appliances until they can be properly repaired.

Stay Clear of Power Lines

Keep a safe distance from downed power lines and any objects or appliances in
contact with them. Electricity poses a significant risk, so exercise caution.

By following these guidelines, you can ensure your safety and the well-being of
those around you during and after an earthquake. Remember, preparedness and
knowledge are key to effectively managing these natural disasters. Stay
informed and stay safe!
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 PRINCIPLES OF EARTHQUAKE
RESISTING DESIGN
• Ductility: Use materials that can bend without breaking to absorb seismic
energy.
• Strength: Ensure structures are strong enough to withstand earthquake forces.
• Stiffness: Balance stiffness to control movement without making the structure
too brittle.
• Redundancy: Design multiple load paths so that failure of one element
doesn’t cause collapse.
• Toughness: Choose materials that resist fracturing and absorb energy.
• Base Isolation: Use flexible bearings to reduce the energy transferred to the
building.
• Energy Dissipation: Incorporate devices to absorb seismic energy,
reducing force on the structure.
• Symmetry and Regularity: Design with regular, symmetrical shapes to
avoid uneven stress distribution.
• Foundation Design: Ensure stable foundations to minimize differential
settlement and ground movement effects.
• Avoidance of Resonance: Adjust the building’s natural frequency to avoid
amplifying seismic motion.
• Continuity and Connectivity: Ensure structural elements are well-
connected to avoid weak points.
• Non-Structural Design: Secure non-structural elements to prevent them
from
becoming hazards.
• These principles aim to create structures that can withstand seismic forces,
minimize damage, and protect lives.

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 CODES TO DESIGN EARTHQUAKE
RESISTANT STRUCTURES
• IS1893 (PART 1) (2002) -Indian Standard Code of Practice for Criteria
for Design of Earthquake Resistant Structures

• IS 13920 (1993) -Indian Standard Code of Practice for Ductile Detailing

of Reinforced Concrete Structures Subjected to Seismic Forces.

• IS 13828 (1993)- Indian Standard Guidelines - Improving Earthquake

Resistance of Low-Strength Masonry Buildings

• IS 4326 (1993)- Earthquake Resistant Design And Construction Of

Buildings Code Of Practice

• IS 13827 (1993)- Indian Standard Guidelines For Improving Earthquake

Resistance Of Earthen Buildings

• IS 13935 (1993)- Seismic Evaluation, Repair And Strengthening Of

Masonry Buildings- guidelines.

• SP 123 (1991)- Design of Beam-Column Joints for Seismic Resistance

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 SEISMIC ZONES OF INDIA
Earthquake-prone regions of the country have been identified based on
scientific inputs related to seismicity, past earthquakes, and the region's
tectonic setup.
Based on these inputs, the Bureau of Indian Standards (BIS) has grouped the
country into four seismic zones: V, IV, III, and II.
Zone V expects the highest level of seismicity, whereas Zone II is
associated with the lowest level.

• ZONE V (VERY SEVERE INTENSITY ZONE): Parts of Jammu and

Kashmir (Kashmir valley); Western part of Himachal Pradesh; Eastern
part of Uttarakhand, Kutch in Gujarat; part of Northern Bihar; all
northeastern states of India and the Andaman & Nicobar Islands.

• ZONE IV (SEVERE INTENSITY ZONE): Ladakh; Remaining parts of

Jammu & Kashmir, Himachal Pradesh and Uttarakhand; Some parts of
Haryana, Parts of Punjab; Delhi; Sikkim; the northern part of Uttar
Pradesh; small portions of Bihar and West Bengal; parts of Gujarat and
small portions of Maharashtra near the west coast and small part of
western Rajasthan.

• ZONE III (MODERATE INTENSITY ZONE): Kerala; Goa;

Lakshadweep islands; parts of Uttar Pradesh and Haryana; remaining parts
of Gujarat and Punjab; parts of West Bengal, western Rajasthan, Madhya
Pradesh; remaining part of Bihar; northern parts of Jharkhand and
Chhattisgarh; parts of Maharashtra, Odisha, Andhra Pradesh, Telangana,
Tamil Nadu and Karnataka.
• ZONE II (LOW INTENSITY ZONE):
Remaining parts of Rajasthan, Uttar Pradesh, Gujarat, Haryana,
Madhya Pradesh, Maharashtra, Odisha, Andhra Pradesh,
Telangana, Karnataka and Tamil Nadu.

22
Approximately, 11% of the country falls in zone v, ~18% in zone iv, ~
30% in zone iii and the remaining in zone ii. A total of ~59% of the
landmass of india (covering all states of india) is prone to earthquakes
of different intensities.

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 Understanding Seismograph and the Richter scale

A seismograph and the Richter scale are essential tools used in seismology to
understand and characterise earthquakes. While they are related to each other,
they serve different purposes. Here’s an elaboration on the difference between a
seismograph and the richter scale.

SEISMOGRAPH

• A seismograph is a device used to measure and record the vibrations or

ground motions caused by earthquakes.
• It consists of a ground motion sensor, typically a mass attached to a fixed
base and a recording system that captures the movements detected by the
sensor.
• Seismographs are essential in monitoring seismic activity, as they provide
valuable data about the intensity, duration and frequency of ground shaking.
• By analyzing the recorded seismograms, scientists can determine various
characteristics of an earthquake, such as its magnitude, location and focal
depth.
• Seismographs also detect other seismic events, such as volcanic eruptions
and underground explosions.

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RICHTER SCALE

• The Richter scale, developed by Charles F. Richter in the 1930s, is a

numerical scale used to quantify the magnitude or strength of an earthquake.
• It measures the energy released during an earthquake by analyzing the
amplitude of seismic waves recorded on seismographs.
• The Richter scale is logarithmic, meaning that each whole number increase
on the scale corresponds to a tenfold increase in the amplitude of the seismic
waves and approximately 31.6 times more energy released. For example, a
magnitude six earthquake releases about 31.6 times more energy than a
magnitude five earthquake.
• The Richter scale provides a standardized measurement for consistent
comparison of worldwide earthquake magnitudes.

DIFFERENCE BETWEEN SEISMOGRAPH AND RICHTER

SCALE
Seismograph Richter Scale
• Used for measuring and • Used for indicating the intensity
recording the vibrations of of an earthquake
earthquakes
• Used for measuring the motions • Used for quantifying the energy
related to the ground, like that is released during an
seismic waves resulting in earthquake
earthquake and volcanic
eruptions

In summary, a seismograph is a device used to measure and record the ground

motions caused by earthquakes. The Seismograph provides the data necessary to
calculate the magnitude of an earthquake, which is then represented on the
Richter scale. At the same time, the Richter scale is a numerical scale used to
quantify the energy released during an earthquake. Together, these tools help
seismologists and scientists better understand and characterise seismic events,
enabling them to assess the impact and potential hazards associated with
earthquakes.

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 STATIC AND DYNAMIC ANALYSIS OF
STRUCTURE
• A static load varies very slowly.
• Dynamic load changes with time fairly quickly in comparison to the structure's
natural frequency.
• As per is 1893-2002 (page no. 25)-
• The dynamic analysis shall be performed to obtain the design seismic force, and
its distribution to different levels along the height of the building and to the
various lateral load-resisting elements, for the following buildings:
a) Regular building greater than 40 m in height in zones iv and v and those greater
than 90 m in height in zones ii and iii. Modelling as per 7.8.4.5 can be used.
b) Irregular buildings- all framed buildings higher than 12 m in zones iv and
v and those greater than 40 m in height in zones ii and iii.
• Note - for irregular buildings, lesser than 40 m in height in zones ii and iii,
dynamic analysis, even though not mandatory, is recommended

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 SIZE OF BUILDINGS
Tall buildings with a large height-to-base ratio:
• Experience significant horizontal floor movement during ground shaking.
• This movement negatively impacts the structure's stability.
• Increases the tendency of the building to overturn.
Short but very long buildings:
• Face numerous damaging effects during earthquake shaking.
Buildings with large plan areas (e.g., warehouses):
• Horizontal seismic forces may be too excessive for columns and walls to bear.
• Such buildings are likely to perform poorly during earthquakes.

HORIZONTAL LAYOUT OF BUILDINGS

BUILDINGS WITH SIMPLE GEOMETRY IN PLAN:
• Generally, perform well during strong earthquakes

BUILDINGS WITH RE-ENTRANT CORNERS (U, V, H, + SHAPED):

• Tend to sustain significant damage during earthquakes

MITIGATING EFFECTS OF INTERIOR CORNERS:

• Buildings with re-entrant corners can be divided into simpler shapes
using separation joints (e.g., breaking an L- shaped plan into two
rectangles

SIMPLE PLAN ALONE IS NOT SUFFICIENT:

• Simple plans with unequal distribution of columns or walls are still
vulnerable.
• These buildings are prone to twisting during earthquake shaking.

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 VERTICAL LAYOUT OF BUILDINGS
EARTHQUAKE FORCES AND LOAD TRANSFER:
• Forces generated at different floor levels must be transferred down to the
ground along the building's height via the shortest path.
• Any deviation or discontinuity in this load transfer path reduces the
building's seismic performance.

VERTICAL ARCHITECTURAL AND STRUCTURAL FEATURES:

• Certain features can negatively impact the building's seismic capacity.

❖ VERTICAL SETBACKS ❖ WEAK OR FLEXIBLE STORY

Buildings with vertical setbacks such Buildings that have fewer columns or
as hotel buildings with a few storys walls in a particular story or with
wider than the rest cause a sudden unusually tall stories, tend to damage or
jump in earthquake forces at the collapse which is initiated in that story.
level of discontinuity.

❖ UNEQUAL COLUMN ❖ HANGING OR FLOATING

HEIGHT ALONG SLOPES COLUMNS:
Buildings on sloppy ground have These columns do not extend the
unequal height columns along the foundation, creating discontinuities in
slope, which causes ill effects like the load transfer path.
twisting and damage in shorter Some buildings rely on these walls to
columns carry earthquake loads to the
foundation.
If these walls stop at an upper level
instead of reaching the ground, the
building is at high risk of severe
damage during earthquakes.

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