This document discusses earthquake classification, magnitude, intensity, energy, source mechanisms, and safety tips. It defines the Richter scale for classifying earthquake magnitude from 1 to 9. Intensity is measured using different scales from I to XII. Larger quakes over magnitude 7 can cause widespread damage, while most people feel quakes of magnitude 4. Before, during, and after an earthquake, certain safety measures should be followed, such as securing furniture, staying away from windows, and evacuating damaged buildings.

1. EARTHQUAKE MAGNITUDE, INTENSITY,
ENERGY, POWER LAW RELATIONS AND
SOURCE MECHANISM
Walter D. Mooney
U.S. Geological Survey
California, USA
e-mail: mooney @ usgs.gov

2. EARTHQUAKE CLASSIFICATION
MAGNITUDE CLASSIFICATION
M ≥ 8.0 Great Earthquake
7.0 ≥ M < 8.0 Major / Large Earthquake
5.0 ≥ M < 7.0 Moderate Earthquake
3.0 ≥ M < 5.0 Small Earthquake
1.0 ≥ M < 3.0 Microearthquake
M < 1.0 Ultra Microearthquake
Hagiwara, 1964

3. NATURE OF EARTHQUAKES
1) Foreshocks
2) Main shock
3) Aftershocks
4) Earthquake Swarm
5) Normal Seismic activity

4. CLASSIFICATION DISTANCE
1) Teleseismic Earthquake > 1000 km
2) Regional Earthquake > 500 km
3) Local Earthquake < 500 km
TYPES OF EARTHQUAKES
1) Tectonic Earthquake
2) Volcanic Earthquake
3) Collapse Earthquake
4) Explosion Earthquake

5. EARTHQUAKE INTENSITY
 Rossi-Forel Intensity Scale (I – X)
 Modified Mercalli (MM) Intensity Scale
(1956 version), (I – XII)
 Medvedev-Sponheuer-Karnik (MSK) Intensity Scale
(1992 Version), (I – XII)
Isoseismals
Isoseismals are the curved lines joining the localities of same intensity.

6. EARTHQUAKE ENERGY
log E = 12 + 1.8 ML
log E = 5.8 + 2.4 mb
log E = 11.4 + 1.5 Ms
1.0 10.0 times about 32 times
0.5 3.2 times about 5.5 times
0.3 2.0 times about 3 times
0.1 1.3 times about 1.4 times
Magnitude Ground Motion Energy
Magnitude versus ground motion and energy

7. POWER LAW RELATIONS
Frequency- magnitude Relation
Log10N = a – bM
Aftershock Attenuation (p-value)
N(t)  t -p
Fractal Dimension
2
~
)
( D
r
r
C

8. SOURCE MECHANISM
(fault-plane solution)
Classification of Faults
 Thrust Fault
 Normal Fault
 Strike-slip Fault
Dynamics of Faulting
Elastic Rebound Theory  Single Couple
 Double Couple

9. Normal fault Regime Thrust fault Regime
Strike-slip fault Regime

10. Foot wall
h
d
55°
35°
Fault
Hanging wall
N
o
r
t
h
F
a
u
l
t
l
i
n
e
Fault Dimension

11. Different Types of Faulting

12. Graben & Horst in Fault System

13. Dynamics of Faulting

14. Elastic Rebound Theory
Reid, 1910

15. • INTENSITY SCALE I
• Scarcely Perceptible - Perceptible to
people under favorable circumstances.
Delicately balanced objects are disturbed
slightly. Still water in containers oscillates
slowly.

16. • INTENSITY SCALE II
• Slightly Felt - Felt by few individuals at
rest indoors. Hanging objects swing slightly.
Still water in containers oscillates
noticeably.

17. • INTENSITY SCALE III
• Moderately Strong - Felt generally by people
indoors and by some people outdoors. Light
sleepers are awakened. Vibration is felt like a
passing of heavy truck. Hanging objects swing
considerably. Dinner, plates, glasses, windows,
and doors rattle. Floors and walls of wood
framed buildings creak. Standing motor cars
may rock slightly. Liquids in containers are
slightly disturbed. Water in containers oscillate
strongly. Rumbling sound may sometimes be
heard.

18. • INTENSITY SCALE IV
• Moderately Strong - Felt generally by people
indoors and by some people outdoors. Light
sleepers are awakened. Vibration is felt like a
passing of heavy truck. Hanging objects swing
considerably. Dinner, plates, glasses, windows,
and doors rattle. Floors and walls of wood
framed buildings creak. Standing motor cars
may rock slightly. Liquids in containers are
slightly disturbed. Water in containers oscillate
strongly. Rumbling sound may sometimes be
heard.

19. • INTENSITY SCALE V
• Strong - Generally felt by most people
indoors and outdoors. Many sleeping people
are awakened. Some are frightened, some
run outdoors. Strong shaking and rocking
felt throughout building. Hanging objects
swing violently. Dining utensils clatter and
clink; some are broken. Small, light and
unstable objects may fall or overturn.
Liquids spill from filled open containers.
Standing vehicles rock noticeably. Shaking
of leaves and twigs of trees are noticeable.

20. • INTENSITY SCALE VI
• Very Strong - Many people are frightened; many
run outdoors. Some people lose their balance.
Motorists feel like driving in flat tires. Heavy
objects or furniture move or may be shifted. Small
church bells may ring. Wall plaster may crack.
Very old or poorly built houses and man-made
structures are slightly damaged though well-built
structures are not affected. Limited rockfalls and
rolling boulders occur in hilly to mountainous
areas and escarpments. Trees are noticeably
shaken

21. • INTENSITY SCALE VII
• Destructive - Most people are frightened and run
outdoors. People find it difficult to stand in upper
floors. Heavy objects and furniture overturn or
topple. Big church bells may ring. Old or poorly-
built structures suffer considerably damage. Some
well-built structures are slightly damaged. Some
cracks may appear on dikes, fishponds, road
surface, or concrete hollow block walls. Limited
liquefaction, lateral spreading and landslides are
observed. Trees are shaken strongly. (Liquefaction
is a process by which loose saturated sand lose
strength during an earthquake and behave like
liquid).

22. • INTENSITY SCALE VIII
• Very Destructive - People are panicky. People find it
difficult to stand even outdoors. Many well-built buildings
are considerably damaged. Concrete dikes and foundation
of bridges are destroyed by ground settling or toppling.
Railway tracks are bent or broken. Tombstones may be
displaced, twisted or overturned. Utility posts, towers and
monuments may tilt or topple. Water and sewer pipes may
be bent, twisted or broken. Liquefaction and lateral
spreading cause man-made structure to sink, tilt or topple.
Numerous landslides and rockfalls occur in mountainous
and hilly areas. Boulders are thrown out from their
positions particularly near the epicenter. Fissures and faults
rupture may be observed. Trees are violently shaken. Water
splash or slop over dikes or banks of rivers.

23. • INTENSITY SCALE IX
• Devastating - People are forcibly thrown to
ground. Many cry and shake with fear. Most
buildings are totally damaged. Bridges and
elevated concrete structures are toppled or
destroyed. Numerous utility posts, towers and
monument are tilted, toppled or broken. Water
sewer pipes are bent, twisted or broken.
Landslides and liquefaction with lateral spreading
and sand boils are widespread. the ground is
distorted into undulations. Trees are shaken very
violently with some toppled or broken. Boulders
are commonly thrown out. River water splashes
violently or slops over dikes and banks.

24. • INTENSITY SCALE IX
• Completely Devastating - Practically
all man-made structures are destroyed.
Massive landslides and liquefaction,
large scale subsidence and uplift of
landforms and many ground fissures
are observed. Changes in river courses
and destructive seiches in large lakes
occur. Many trees are toppled, broken
and uprooted.

25. intensity is expressed
using Roman numerals (I,
II, III) while
magnitude uses Hindu-
Arabic numerals (2, 3, 4).

26. Earthquakes with a magnitude of
2 may or may not be felt.
Those that are felt by most people
have a magnitude of 4.
Magnitude 6 quakes can lead to a
lot of damage in highly populated
areas.

27. Earthquakes with a magnitude of 7
can cause severe damage.
A magnitude 8 or 9 quake results in
widespread destruction, especially
near the epicenter.
Luckily, only one or two occur every
year

29. Before the earthquake
• Prepare homes or schoolrooms by strapping
heavy furniture to the walls.
• Check the stability of hanging objects.
Breakable items, harmful chemicals and
flammable materials should be stored
properly.
• Know exit routes.
• Know where fire extinguishers and first aid
kits are located.

30. Before the earthquake
• Prepare an emergency supply kit
that includes water, canned food,
can opener, clothing, blanket,
battery-operated radio, flashlight,
and extra batteries.
• Participate in regular earthquake
drills

31. During the earthquake
• Stay calm.
• If you are at home or inside a
building, stay there.
• Duck under a sturdy desk or table
and hold on to it.
• Stay away from glass windows,
cabinets, and heavy objects. Beware
of falling objects.

32. During the earthquake
• If you are outside, move to an open
area.
• Stay away from trees, powerlines,
and concrete structures.

33. During the earthquake
• Move away from steep slopes which
could be affected by landslides.
• If you are near the shore, move
quickly to higher grounds.
• Tsunamis may follow.

34. After the earthquake
• Do not use elevators or enter damaged
buildings.
• Check yourself and others for injuries.
• Check for spills of chemical, toxic, and
flammable materials.
• If you need to evacuate, leave a message
and bring your emergency kit.
• Listen to the radio for updates.