Anatomy of an earthquake

1. ANATOMY OF AN
EARTHQUAKE

3. THE THREE BASIC TYPES OF FAULTS

5. THE TWO TYPES OF SEISMIC WAVES
1) BODY WAVES

6. THE TWO TYPES OF SEISMIC WAVES
2) SURFACE WAVES

7. EARTHQUAKE
MAGNITUDE &
INTENSITY

8. EARTHQUAKE MAGNITUDE & INTENSITY
Magnitude is the measure of the energy
released by the earthquake, measured by an
instrument called seismometer (the instrument
used to detect seismic waves).
 Intensity refers to the effects and damage
caused by an earthquake. It is determined by
actual observation or on-site inspection of the
affected areas, including interviews with
people.

9. PHILVOLCS
EARTHQUAKE
INTENSITY SCALE

10. PHILVOLCS EARTHQUAKE INTENSITY SCALE
(MODIFIED MERCALLI SCALE)

11. PHILVOLCS EARTHQUAKE INTENSITY SCALE
Perceptible to people
under favorable
circumstances.
Delicately balanced
objects are disturbed
slightly.
Still water in containers
oscillate slowly.

12. PHILVOLCS EARTHQUAKE INTENSITY SCALE
Felt by few individuals
at rest indoors.
Hanging objects swing
slightly.
Still water in containers
oscillate noticeably.

13. PHILVOLCS EARTHQUAKE INTENSITY SCALE
Felt by many people
indoors, especially in
upper floors of the
buildings.
Dizziness and nausea
are experienced by
some people.
Hanging objects swing
moderately.

14. PHILVOLCS EARTHQUAKE INTENSITY SCALE
Felt generally by people
indoors and by some
people outdoors.
Light sleepers are
awakened.
Vibration is felt like the
passing of a heavy truck.
A rumbling sound may
sometimes be heard.

15. PHILVOLCS EARTHQUAKE INTENSITY SCALE
 Generally felt by most
people indoors and
outdoors.
 Many sleeping people are
awakened.
 Strong shaking and rocking
felt throughout the building.
 Hanging objects swing
violently.
 Standing vehicles rock
noticeably.

16. PHILVOLCS EARTHQUAKE INTENSITY SCALE
 Some people lose their
balance.
 Motorists feel like they are
driving with flat tires.
 Heavy objects or furniture
move or may be shifted.
 Very old or poorly-built
houses and man-made
structures are slightly
damaged, though well-built
structures are not affected.

17. PHILVOLCS EARTHQUAKE INTENSITY SCALE
People find it difficult to
stand in upper floors.
Heavy objects and furniture
overturn or topple.
Some well-built structures
are slightly damaged.
Some cracks may appear
on dikes, fish ponds, road
surfaces or concrete hollow
block walls.
Trees are shaken strongly.

18. PHILVOLCS EARTHQUAKE INTENSITY SCALE
 People find it difficult to stand
even outdoors.
 Many well-built buildings are
considerably damaged.
 Concrete dikes and
foundations of bridges are
destroyed by ground settling
or toppling.
 Railway tracks are bent or
broken.
 Fissures and fault rupture
may be observed.

19. PHILVOLCS EARTHQUAKE INTENSITY SCALE
People are forcibly
thrown to ground.
Most buildings are
totally damaged.
Bridges and elevated
concrete structures are
toppled or destroyed.

20. PHILVOLCS EARTHQUAKE INTENSITY SCALE
Practically all man-made
structures are
destroyed.
Massive landslides and
liquefaction, subsidence
and uplifting of
landforms and many
ground fissures are
observed.