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Earthquake
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Earthquake is a sudden shaking of ground due to natural causes (rock displacements, landslide,
avalanche, volacanic eruption, meteoritic impact, sub-marine sea faulting, etc) so to refer it as
natural earthquake. The shaking of ground may be due to several other man-made agencies, such
as, explosions due to chemical blasts or nuclear blasts or rock burst due to mining activities, and
reservoir induced earthquakes. Occurrence of earthquake is still a puzzle for the entire scientific
community as its generating mechanism does not follow a thumb rule. It can hit anywhere at any
point of time and that is why earthquake is regarded as most unpredictable, uncontrollable and
unfathomable cause of bringing disasters to both flora and fauns. Scale of disaster due to
earthquake is dictated by several earthquake parameters. Among which are earthquake magnitude
(extent of energy release during the earthquake), focal depth or hypocenter (the depth at which
the rupture initiates), the epicenter location of the earthquake (the vertical projection of the
hypocenter to the surface). Thus bigger magnitude earthquake at shallower depth (< 30 km) with
its epicenter location near the densely populated region can inflict a severe damage to both
property and person, whilst the reverse may lead to relatively less damaging effects in the
earthquake prone zones. In addition to that earthquake occurrence time and building typology also
play their important roles in influencing the degree of damage due to earthquakes in the region. It
is rightly said that “earthquake does not kill the people; it is structure which kills the people”!
Several pieces of studies revealed that upper crust of the earth up to a depth of 18 km from the
surface is seismically active because of its brittle behavior, while lower crust between 18 km and
33 km depth inside the earth is seismically less active due its ductility under high temperature. The
boundary between the lower crust and upper crust is referred to as Conrad discontinuity, while the
boundary between the lower Crust and the upper Mantle is referred to as Mohorovicic
discontinuity, in short it is mentioned as Moho discontinuity, which varies from shallower (10 – 12
km) beneath the Ocean to deeper (70 – 80 km) beneath the Himalaya. The entire crust and upper
Mantle constitute “Lithosphere”, whose thickness is found to varying from 100 km to 150 km. It is
a solid lithosphere which floats on the semi-viscous layer of the earth called Aesthenosphere, a part
of the lower Mantle. The lithosphere constitutes an important ingredient of Earth’s physiographic
that divides entire Earth into several tectonic blocks to explain the geodynamics of the Earth and
seismogenesis in diverse tectonic environ. Earthquake can hit either within the same tectonic block
/ plate (intra-plate earthquake) or at the boundary of two or more tectonic plates (plate-boundary
earthquakes). The plate-boundary earthquakes are frequent (e.g., earthquakes in Himalayan
region; earthquakes in the Andaman – Nicobar region; earthquakes in the Ring of Fire zone, Alaska,
Japan, Chile ), while the intra-plate earthquakes are less frequent (e.g., earthquakes in stable
continental region of India; the 1819 Kutchch earthquake; 1993 Latur earthquake; 2001 Bhuj
earthquake). The great damaging earthquakes are generally accompanied with secondary effects,
such as tsunamis, liquefactions, landslides, volcanic (lava and mud) eruptions; nuclear emissions,
and fires that may multiply the degree of losses due earthquake many folds. The recent occurrence
of the 2004 tsunami-genic Sumatra – Andaman earthquake (Mw 9.3) and the 11th March 2011
Japan tsunamigenic earthquake ( Mw 9.0) are appropriate example to understand how a huge loss
of both people and property was mainly due to secondary effect of tsunamis rather than that of
primary earthquake shakings.
Occurrence of damaging Earthquakes are a major problem for the mankind, killing more than 17000
persons per year in the twentieth century. It causes multifaceted damages and destruction to life and property.
What to do about earthquake risk and how to mitigate earthquake induced damages, particularly in the
developing countries, has been a challenging issue and still need a coordinated effort to tackle the
regional menace that occur during the killer earthquakes. Assessing the earthquake risk and determining
mitigation alternatives varies from country to country. Reduction in the earthquake risk involves the use of
knowledge, methodologies adopted based on the geopolitical boundaries. More so on multi-objective-multi-stake
holder decision to be taken. Making a decision on what to do, depends on the site specific data collected from
affected region, including multifaceted role played by geosciences, engineering, disaster planning and response,
techno-legal, insurance and economics.
Several earthquakes in the recent past remind us about the high level of seismic hazard and risk prevailing in the
country. About 59% of India's land area is under the threat of moderate to severe earthquake shaking intensity
VII and higher. During the last two decades, several major earthquakes have resulted in over 100,000
deaths in South Asian nations, especially located in the vicinity of Himalaya and in the oceanic
subduction zone of Andman – Nicobar Island region . The regions far away from the Himalaya and other
inter-plate boundaries, which were once considered to be relatively safe from strong shaking, have also
experienced several devastating earthquakes. The huge losses of life and property in the earthquake-prone areas
of the region have shown that the built-environment is extremely fragile, and our ability to respond to these
events is extremely inadequate. It has been found that the casualties were caused primarily due to the collapse
of buildings that have usually no earthquake-resistant features. This emphasizes the need for strict compliance of
town planning bye-laws and earthquake-resistant building codes in India.

About Earthquake

Can we predict earthquakes?

Seismicity of south Asia

Important organizations in India

Early warning and prediction

Preventive and mitigation measures

How can I protect myself during an earthquake?


Scale

About Earthquake
Weblinks
About Earthquake
What is an Earthquake?
An earthquake is the motion or trembling of the ground produced by sudden displacement of rock in the Earth's
crust. Earthquakes result from crustal strain, volcanism, landslides, and collapse of caverns. Stress accumulates
in response to tectonic forces until it exceeds the strength of the rock. The rock then breaks along a preexisting
or new fracture called a fault. The rupture extends outward in all directions along the fault plane from its point of
origin (focus). The rupture travels in an irregular manner until the stress is relatively equalized. If the rupture
disturbs the surface, it produces a visible fault on the surface. Earthquakes are recorded by seismograph
consisted of seismometer, a shaking detector and a data recorder. The moment magnitude of an earthquake
is conventionally reported, or the related and mostly obsolete Richter magnitude, with magnitude 3 or lower
earthquakes being mostly imperceptible and magnitude 7 causing serious damage over large areas. Intensity of
shaking is measured on the modified Mercalli scale. In India Medvedev-Sponheuer-Karnik scale, also known as
the MSK or MSK-64, which is a macro-seismic intensity scale, is used to evaluate the severity of ground shaking
on the basis of observed effects in an area of the earthquake occurrence. Due to earthquake seismic waves are
generated and measurements of their speed of travel are recorded by seismographs located around the planet.
There are two main types of seismic waves - body and surface waves. The body waves have Primary (P-) and
secondary (S-wave) types. Demonstration of seismic waves are explained here Demo
Why earthquake occurs?
Earthquakes occur due to the sudden release of stored strain energy inside the earth crust. The earth is divided
into several major and micro tectonic plates, some 50 miles thick, which move slowly and continuously over
the earth's aesthenosphere. Most earthquakes occur as the result of slowly accumulating stress that causes the
ground to slip abruptly along a geological fault plane on or near a plate boundary. The resulting waves of
vibration within the earth create ground motion at the surface that vibrates in a very complex manner.
What are the various types of earthquake?
Classification of earthquake is based on several parameters. Based on scale of magnitude (M),
earthquake may be of Micro (M < 3.5) or macro (M > 3.5) type. Depending up on the extent of
energy released and strength of the ground shaking it may be of several types, like moderate
strong, very strong, great and very great earthquake. Depending up on the scale of damage, the
earthquake may be of various types, such as Less damaging earthquake, Moderate damaging
earthquake, and catastrophic earthquake. Depending up on the focal depth (h) of the event, it
could be shallow earthquake (d< 70 km); intermediate depth earthquake (70 < h < 300 km); the
deep earthquake (300 < h < 700 km). Depending up on the location of events in different tectonic
settings, earthquake may be of intra-plate, inter-plate, and sub-oceanic earthquake. Depending up
on involvement of other agencies / phenomena with earthquake genesis, it may be of several
types, such as Reservoir induced; Fluid-driven earthquake; Tsunamigenic earthquake, and volcanic
earthquake. Depending up on the type of faulting involved during earthquake genesis, earthquake
may be categorized into several categories, such as normal faulting, reverse faulting, thrust
faulting, and mega-thrust earthquake. Depending up on the frequency content, the earthquake
may be of Low-Frequency tremors or high – Frequency tremors. Depending up on the epicenter
distance (distance between earthquake mainshock and the recording stations), the earthquake
may
be
classified
into
Local,
Regional
and
Global
earthquake.
For more Information Click here (types of earthquakes).
What one should know about earthquakes?
Earthquakes can be violent, and they remain unpredictable. A comprehensive background note on the
earthquakes for commoner is given in the earthquake tips prepared by several institutions of SAARC
countries, like India, Bhutan, Nepal and Pakistan.
Intensity scale
It manifests the degree of damage, which gets diminished as we go away from the main shock
source zone and the reverse is also true. There are several earthquake intensity scale, which can be
referred from the relevant pages.

European
http://en.wikipedia.org/wiki/European_Macroseismic_Scale

USA (MM)
http://en.wikipedia.org/wiki/Mercalli_intensity_scale

Japan (JMA)
http://en.wikipedia.org/wiki/Japan_Meteorological_Agency_seismic_intensity_scale

Can we predict earthquakes?
Can we predict Earthquakes?
With present state of knowledge of science, it is not possible to predict earthquake. It is so because
the physics involved in earthquake genesis is very complex. The mechanism of earthquake
generating processes is still not adequately understood us because of involvement of multicomponent parameters in earthquake genesis.
For more Information Click here
There are several school of thoughts on the earthquake prediction, notable among is Jim Berkland, a retired
geologist from USGS, who, according to his supporters, has 80% accuracy rates. Recently a book by Cal Orey
was released.
For more Information Click here
South Asian Profile
Most parts of south Asian countries (Afghanistan, Bhutan, India, Nepal and Pakistan) are
seismically very vulnerable because of their close proximity to the young and dynamic Himalayan
belt, extending from Northwest to Northeast. There were several past damaging earthquakes hit
the countries of south Asia, especially by large magnitude earthquakes that inflicted a huge loss to
both property and person (please see Table 1). Most recently, the 2005 Muzaffrabad earthquake
(Mw 7.6) caused a huge loss of property and lives of people of Kashmir. About 85,000 people
reported to have killed during the earthquake. The 1934 Nepal – Bihar earthquake (Mw 8.0) was
another example that killed about 12,000 people of two countries, Nepal and India. India's high
earthquake risk and vulnerability is evident from the fact that about 59 per cent of India's land area could face
moderate to severe earthquakes. During the period 1990 to 2006, more than 23,000 lives were lost due to 6
major earthquakes in India, which also caused enormous damage to property and public infrastructure. The
occurrence of several devastating earthquakes in areas hitherto considered safe from earthquakes indicates that
the built environment in the country is extremely fragile and our ability to prepare ourselves and effectively
respond to earthquakes is inadequate. Some facts on Indian earthquake risk scenario can be found.
The building collapse results in the widespread loss of lives and property including lifeline infrastructure like
roads, dams and bridges, hospitals as well as public utilities like power and water supply installations. Past
earthquakes have shown that over 95 per cent of the lives lost were due to the collapse of buildings that were
not earthquake-resistant. Though there are no. of earthquake resistant design codes and other regulations
available proper implementation of these urgently requires serious attention.
India has advanced considerably in developing earthquake resistant codes of practice and guidelines for
constructing RCC and steel framed buildings, brick or stone masonry buildings and combination of clay, wood,
bamboo and thatched houses. Yet high level of earthquake risk in our country�s context is mostly attributed to
the unplanned and ill planned urban infrastructures developments. In order to reduce vulnerability it is important
to create proper awareness about earthquake induced damages and their mitigation measures.
During the International Decade for Natural Disaster Reduction (IDNDR) observed by the United Nations (UN) in
the 1990s, India witnessed several earthquakes like the Uttarkashi earthquake of 1991, the Latur earthquake of
1993, the Jabalpur earthquake of 1997, and the Chamoli earthquake of 1999. Some of the photographs of Indian
earthquakes are available here Click here
These were followed by the Bhuj earthquake of 26 January 2001 and the Jammu & Kashmir earthquake of 8
October 2005. All these major earthquakes established that the casualties were caused primarily due to the
collapse of buildings. However, similar high intensity earthquakes in the United States, Japan, etc., do not lead to
such enormous loss of lives, as the structures in these countries are built with structural mitigation measures and
earthquake-resistant features.
The National Information Center of Earthquake Engineering hosted at Indian Institute of Technology Kanpur is
intended to collect and maintain information resources on Earthquake Engineering and make these available to
the interested professionals, researchers, academicians and others with a view to mitigate earthquake disasters
in India.Various initiatives taken up by Ministry of Home Affairs.
For more Information Click here
Some of the important issues in earthquake risk mitigation in Indian context are:

Earthquake hazard and risk mitigation

Earthquake resistant design and rehabilitation of structures

Indian standards and guidelines on earthquake technology

Seismic evaluations and retrofitting of lifeline buildings

Disaster safe construction practices and issues

Techno-legal and techno-financial framework for earthquake protection compliance


Training and Capacity building of masons, architect and engineers
India Govt. initiatives in the earthquake risk reduction
For more Information Click here
Global Profile
Globally, earthquakes have caused massive destruction upto the present day. It represents a risk to
many countries of the world, particularly western North and South America, Japan, China, the
Phillipines, New Zealand, northern part of India and the middle east region. Most recently, about
20,000 people were reported either killed or missing during the great mega-thrust
tsunamigenic Japan earthquake (Mw 9.0) that struck on 11th March 2011 beneath the NE
Japan forearc region. Besides, a great killer earthquake of magnitude (Mw 7.9) hit Haiti in
January 2010 in which about 223,000 people were killed. Other earthquake which caused
a severe loss to property and person during the year 2010 are China and Chile earthquake.
A comprehensive details of earthquake as a science and understanding of various facts that lead to
enormous
damages
and
Real time seismic monitor of the earth
destructions
are
available
here
Click
here.
Early warning and prediction
Earthquake early warning
Earthquake early warning (EEW) can provide a few seconds to tens of seconds warning prior to ground shaking
during an earthquake. Several countries, such as Japan, Taiwan, Mexico have adopted this methodology based
on the fact that such warning can (1) rapidly detect the initiation of an earthquake, (2) determine the size
(magnitude) and location of the event, (3) predict the peak ground motion expected in the region around the
event, and (4) issue a warning to people in locations that may expect significant ground motion.
For more Information Click here
While there is strong need for comprehensive training in the emergency response some tips for EEW in Japan are
enlisted here Click here
Humanitarian early warning service (HEWS) provides information on various hazards, including earthquake.
For more Information Click here
Prediction of earthquake is still a subject of speculations yet several schools of thoughts are available. In the
effort to predict earthquakes, people have tried to associate an impending earthquake with such varied
phenomena as seismicity patterns, electromagnetic fields, weather conditions and unusual clouds, radon or
hydrogen gas content of soil or ground water, water level in wells, animal behavior, and the phases of the moon.
For more Information Click here
Earthquake early warning system
Earthquake early warning provides an alarm that strong shaking is due soon to arrive, and the more quickly that
the magnitude of an earthquake can be estimated, the more useful is the early warning. Receiving a warning, a
person may have a few tens of seconds at longest to take actions, but if the focus is too close there may be
cases in which strong tremors come ahead.
For more Information Click here
Preventive and mitigation measures
When earthquake strikes a building is thrown mostly from side to side, and also up and down along with the
building foundation the building structure tends to stay at rest, similar to a passenger standing on a bus that
accelerates quickly. Building damage is related to the characteristics of the building, and the duration and
severity of the ground shaking. Larger earthquakes tend to shake longer and harder and therefore cause more
damage to structures
For more Information Click here
Structural
No buildings can be made 100% safe against earthquake forces. Instead buildings and infrastructures can be
made earthquake resistant to certain extent depending upon serviceability requirements. Earthquake resistant
design of buildings depends upon providing the building with strength, stiffness and inelastic deformation
capacity which are great enough to withstand a given level of earthquake-generated force. This is generally
accomplished through the selection of an appropriate structural configuration and the careful detailing of
structural members, such as beams and columns, and the connections between them
For more Information Click here
There are several different experimental techniques that can be used to test the response of structures to verify
their seismic performance, one of which is the use of an earthquake shaking table (a shaking table, or
simply shake table). This is a device for shaking structural models or building components with a wide range of
simulated ground motions, including reproductions of recorded earthquakes time-histories.
To view the list of shaking Table Click here
Nonstructural
The non-engineered traditional construction commonly practiced in different areas of the country depends
greatly on the respective local context of the area. In other words the technologies vary significantly from area to
area. These technologies have evolved and as a result have got optimized. In India an overwhelming majority of
houses, are of non-engineered load bearing type. These structures, especially houses, have been traditionally
built over the past century or longer, using the locally available materials and the locally practiced technologies
that have been most common in the area including stone, bricks, earth, lime and timber for walls, and clay tiles,
stone or mud for roofing supported on under-structure made of local timber such as Teak, Acacia, Neem,
Deodar, Pine and also Bamboo. In the recently built structures one also finds a mix of the traditional and new
materials/technology such as cement, concrete and steel. The structures have pitched roof or flat roof, and are
single story or double story.
After Bhuj earthquake significant effort were taken to repair and strengthening of damaged buildings. A guideline
for Repair and strengthening guide for earthquake damaged lowrise domestic buildings in Gujarat is made
available here Click here
Seismic retrofitting
Seismic retrofitting is the modification of existing structures to make them more resistant to seismic activity,
ground motion, or soil failure due to earthquakes. With better understanding of seismic demand on structures
and with our recent experiences with large earthquakes near urban centers, the need of seismic retrofitting is
well acknowledged.
For more Information Click here

EQ and liquefaction weblinks
http://www.ce.washington.edu/~liquefaction/html/links/links.html

Liquefaction
http://www.ce.washington.edu/~liquefaction/html/main.html

Geotechnical EQ engineering
http://www.geoengineer.org/learnbyhy-earthquake.aspx

Scale
Richter
Approximate
Magnitude
Approximate
TNT for
Seismic
Energy
Yield
Joule
equivalent
Example
0.0
1 kg (2.2 lb)
4.2 MJ
0.5
5.6 kg (12.4 lb) 23.5 MJ
Large Hand grenade
1.0
32 kg (70 lb)
Construction site blast
1.5
178 kg (392 lb) 747.6 MJ
WWII conventional bombs
2.0
1 metric ton
Late WWII conventional bombs
2.5
5.6 metric tons 23.5 GJ
WWII blockbuster bomb
3.0
32 metric tons
134.4 GJ
Massive Ordnance Air Blast bomb
3.5
178 metric tons 747.6 GJ
Chernobyl nuclear disaster, 1986
4.0
1 kiloton
4.2 TJ
Small atomic bomb
4.5
5.6 kilotons
23.5 TJ
134.4 MJ
4.2 GJ
5.0
32 kilotons
134.4 TJ
Nagasaki atomic bomb (actual seismic yield was
negligible since it detonated in the atmosphere. The
Hiroshima atomic bomb was 15 kilotons )
Lincolnshire earthquake (UK), 2008
5.4
150 kilotons
625 TJ
2008 Chino Hills earthquake (Los Angeles, United
States)
5.5
178 kilotons
747.6 TJ
ittle Skull Mtn. earthquake (NV, USA), 1992 Alum Rock
earthquake (CA, USA), 2007
6.0
1 megaton
4.2 PJ
Double Spring Flat earthquake (NV, USA), 1994
6.5
5.6 megatons
23.5 PJ
Rhodes (Greece), 2008
6.7
16.2 megatons 67.9 PJ
Northridge earthquake (CA, USA), 1994
6.9
26.8 megatons 112.2 PJ
San Francisco Bay Area earthquake (CA, USA), 1989
7.0
32 megatons
134.4 PJ
7.1
50 megatons
210 PJ
Energy released is equivalent to that of Tsar Bomba, the
largest thermonuclear weapon ever tested.
7.5
178 megatons
747.6 PJ
Kashmir earthquake (Pakistan), 2005
Antofagasta earthquake (Chile), 2007
7.8
600 megatons
2.4 EJ
Tangshan earthquake (China), 1976`
8.0
1 gigaton
4.2 EJ
Toba eruption 75,000 years ago; which, according to
the Toba catastrophe theory, affected modern human
evolution
San Francisco earthquake (CA, USA), 1906
Queen Charlotte earthquake (BC, Canada), 1949
México City earthquake (Mexico), 1985
Gujarat earthquake (India), 2001
8.5
5.6 gigatons
23.5 EJ
Sumatra earthquake (Indonesia), 2007
9.0
32 gigatons
134.4 EJ
Lisbon Earthquake (Lisbon, Portugal), All Saints Day,
1755
9.2
90.7 gigatons
379.7 EJ
Anchorage earthquake (AK, USA), 1964
9.3
114 gigatons
477 EJ
Indian Ocean earthquake, 2004 (40 ZJ in this case)
9.5
178 gigatons
747.6 EJ
Valdivia earthquake (Chile), 1960 (251 ZJ in this case)
10.0
1 teraton
4.2 ZJ
Never recorded.

Richter
Description
Magnitudes
Frequency of
Occurrence
Earthquake Effects
Less than 2.0 Micro
Microearthquakes, not felt.
About 8,000 per
day
2.0-2.9
Minor
Generally not felt, but recorded.
About 1,000 per
day
3.0-3.9
Minor
Often felt, but rarely causes damage.
49,000 per year
(est.)
4.0-4.9
Light
Noticeable shaking of indoor items, rattling noises.
Significant damage unlikely.
6,200 per year
(est.)
5.0-5.9
Moderate
Can cause major damage to poorly constructed buildings
over small regions. At most slight damage to well800 per year
designed buildings.
6.0-6.9
Strong
Can be destructive in areas up to about 160 kilometres
(100 mi) across in populated areas.
120 per year
7.0-7.9
Major
Can cause serious damage over larger areas.
18 per year
8.0-8.9
Great
Can cause serious damage in areas several hundred
miles across.
1 per year
9.0-9.9
Great
Devastating in areas several thousand miles across.
1 per 20 years
10.0+
Epic
Never recorded; see below for equivalent seismic energy Extremely rare
yield.
(Unknown)

(Based
on
U.S.
Geological
Survey
documents.)
JMA Scale
Shindo scale
Magnitu
deShindo
Number
(Shindo
Number People
in
Japanes
e) /
Meter
reading
Reinfor
ced
Indoor
Outdoor
Wooden concret
situation situatio
Lifelines
houses e
s
ns
building
s
Ground
and
slopes
Peak
ground
accelerat
ion
0 (0) / 00.4
Impercept
ible to
people.
Less than
0.008 m/s²
1 (1) /
0.5-1.4
Felt by
only some
people in
the
building.
0.008–
0.025 m/s²
2 (2) /
1.5-2.4
Felt by
most
people in
the
building.
Hanging
objects
such as
lamps
swing
0.025–
0.08 m/s²
Some
people
awake.
Felt by
most
people in
the
building.
Some
people are
frightened
.
slightly
Dishes in
a
cupboard
rattle
occasional
ly
Electric
wires
swing
slightly
0.08–0.25
m/s²
4 (4) /
3.5-4.4
Many
people are
frightened
. Some
people try
to escape
from
danger.
Most
sleeping
people
awake.
Hanging
objects
swing
considera
bly and
dishes in a
cupboard
rattle.
Unstable
ornaments
fall
occasional
ly.
Electric
wires
swing
considera
bly.
People
walking
on a
street and
some
people
driving
automobil
es notice
the
tremor.
0.25–0.80
m/s²
5-lower
(5弱) /
4.5-4.9
Hanging
objects
swing
violently.
Most
Most
people try Unstable
to escape ornaments
from a
fall.
danger.
Occasional
Some
ly, dishes
people
in a
find it
cupboard
difficult to and books
move.
on a
bookshelf
fall and
furniture
moves.
People
notice
electriclight poles
swing.
Occasiona
lly,
windowpa
nes are
broken
and fall,
unreinforc
ed
concreteblock
walls
collapse,
and roads
suffer
damage.
Occasion
ally, less
earthquak
eresistant
houses
suffer
damage
to walls
and
pillars.
Occasion
ally,
cracks
are
formed in
walls of
less
earthquak
eresistant
buildings.
Occasion
ally,
A safety device
cracks
cuts off the gas
appear in
service at some
soft
houses. On rare ground.
occasions water
and
pipes are
rockfalls 0.80–1.40
damaged and
and small m/s²
water service is
slope
interrupted.
failures
(Electrical service take
is interrupted at place in
some houses)
mountain
ous
districts
5-upper
(5強) /
5.0-5.4
Most
dishes in a
cupboard
and most
books on
a
bookshelf
fall.
Occasional
ly, a TV
set on a
rack falls,
heavy
furniture
In many
cases,
unreinforc
ed
concreteblock
walls
collapse
and
tombston
es
overturn.
Many
automobil
Occasion
ally, less
earthquak
eresistant
houses
suffer
heavy
damage
to walls
and
pillars
and lean.
Occasion
ally, large
cracks
are
formed in
walls,
crossbea
ms and
pillars of
less
earthquak
eresistant
buildings
Occasion
ally,
cracks
Occasionally, gas
appear in
pipes and / or
soft
water mains are
ground.
damaged.(Occasi
and
1.40–2.50
onally, gas service
rockfalls m/s²
and / or water
and small
service are
slope
interrupted in
failures
some regions)
take
place in
mountain
3 (3) /
2.5-3.4
Many
people are
considera
bly
frightened
and find it
difficult to
move.
such as a
chest of
drawers
falls,
sliding
doors slip
out of
their
groove
and the
deformati
on of a
door
frame
makes it
impossible
to open
the door.
es stop
because it
becomes
difficult to
drive.
Occasiona
lly,
poorlyinstalled
vending
machines
fall.
and even
highly
earthquak
eresistant
buildings
have
cracks in
walls.
ous
districts.
6-lower
(6弱) /
5.5-5.9
Occasion
ally, less
earthquak
A lot of
eheavy and
resistant
unfixed
In some
houses
furniture buildings,
collapse
moves
wall tiles
Difficult to
and even
and falls. and
keep
walls and
It is
windowpa
standing.
pillars of
impossible nes are
highly
to open
damaged
earthquak
the door and fall
ein many
resistant
cases.
houses
are
damaged.
Occasion
ally, walls
and
pillars of
less
earthquak
eresistant
buildings
are
destroyed
and even
highly
earthquak
eresistant
buildings
have
large
cracks in
walls,
crossbea
ms and
pillars.
Gas pipes and /
or water mains
are damaged.(In
some regions, gas
service and water
service are
interrupted and
electrical service
is interrupted
occasionally.)
Occasion
ally,
cracks
appear in
the
2.50–3.15
ground, m/s²
and
landslides
take
place.
6-upper
(6強) /
6.0-6.4
Many,
less
earthquak
eresistant
houses
collapse.
In some
cases,
even
walls and
pillars of
highly
earthquak
eresistant
houses
are
heavily
damaged.
Occasion
ally, less
earthquak
eresistant
buildings
collapse.
In some
cases,
even
highly
earthquak
eresistant
buildings
suffer
damage
to walls
and
pillars.
Occasionally, gas
mains and / or
water mains are
damaged.(Electric
al service is
interrupted in
some regions.
Occasionally, gas
service and / or
water service are
interrupted over a
large area.)
Occasion
ally,
cracks
appear in
the
3.15–4.00
ground, m/s²
and
landslides
take
place.
ost heavy
and
unfixed
Impossibl
furniture
e to keep
moves
standing
and falls.
and to
Occasional
move
ly, sliding
without
doors are
crawling.
thrown
from their
groove.
In many
buildings,
wall tiles
and
windowpa
nes are
damaged
and fall.
Most
unreinforc
ed
concreteblock
walls
collapse.
7 (7) /
6.5- up
In most
buildings,
wall tiles
and
Thrown by Most
windowpa
the
furniture nes are
shaking
moves to damaged
and
a large
and fall.
impossible extent
In some
to move
and some cases,
at will.
jumps up. reinforced
concreteblock
walls
collapse.
Occasion
ally, even
highly
earthquak
eresistant
buildings
are
severely
damaged
and lean.
Occasion
ally, even
highly
earthquak
eresistant
buildings
are
severely
damaged
and lean.
The
ground is
considera
bly
distorted
by large
cracks
and
Electrical service
fissures,
gas service and
and slope
water service are
failures
interrupted over a
and
large area.
landslides
take
place,
which
occasiona
lly change
topograp
hic