The document describes the Philippine Institute of Volcanology and Seismology (PHILVOLCS) earthquake intensity scale, which ranks earthquakes from intensity level 1 to 10 based on their observed effects on people, structures, and the earth's surface. Intensity 7 earthquakes are described as being destructive and causing cracks in structures, while an intensity 10 earthquake would be completely devastating and destroy virtually all human infrastructure. The intensity of an earthquake typically lessens as the distance from the earthquake's focus increases.

1. By: Jan del Rosario

2. PHILVOLCS
Philippine Institute of Volcanology and
Seismology
PEIS – PHILVOLCS Earthquake Intensity Scale

3. Delicately balanced objects are disturbed
slightly.
Still water in containers oscillates slowly.
Intensity 1 – Scarcely Perceptible

4. Felt by few
individuals at rest indoors.
Hanging objects swing
slightly.
Intensity 2 – Slightly Felt

5. Dizziness and nausea are
experienced by some people.
Intensity 3 - Weak
Vibration is felt like one passing of
a light truck.

6. Dinner, plates, glasses,
windows and doors rattle.
Floors and walls of wood
framed buildings creak.
Standing motor cars may
rock slightly. Rumbling
sound may sometimes be
heard.
Intensity 4 – Moderately Strong
Vibration is felt like a passing
of heavy truck.

7. Intensity 5 - Strong
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.

8. 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.
Intensity 6 – Very Strong

9. Intensity 7 - Destructive
Big church bells may ring. Some cracks may appear on dikes,
road surface, or concrete hollow block walls.

10. Intensity 8 – Very Destructive
Liquefaction and lateral spreading cause man- made structure
to sink, tilt or topple. Numerous landslides and rockfalls occur
in mountainous and hilly areas.

11. Intensity 9 - 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.

12. Practically all man-made structures are destroyed.
Massive landslides and liquefaction, large scale
subsidence and uplifting of land forms and many ground
fissures are observed.
Intensity 10 – Completely Devastating

13. Suppose an Intensity 7 earthquake occurred in
Nueva Ecija, would the intensity be the same in
the neighboring provinces near the focus, why or
why not?

14. 1. PHILVOLCS stands for __________.
Daily Checkup
2. What intensity is capable of destroying all
man made structures?
3. As you go away from the focus, the intensity
_________.

15. PHILVOLCS
Philippine Institute of Volcanology
and Seismology
PEIS – PHILVOLCS Earthquake
Intensity Scale

16. Assignment:
On a one fourth sheet of paper,
differentiate intensity from magnitude
in not more than 2 sentences.