EARTHQUAKE

Question 1

is the vibration of earth’s surface caused by waves coming from a source of disturbance inside the earth

Answer 1

EARTHQUAKE

Question 2

The typical characteristics of earthquake depends on

Answer 2

1. Stress drop during the slip
2. Total fault displacement
3. Size of slipped area
4. Roughness of the slipping process
5. Fault shape (Normal fault, Reverse fault, Strike slip fault)
6. Proximity of the slipped area to the ground surface
7. Soil condition

Question 3

As the waves radiate from the fault, they undergo geometric ________________ due to loss of energy in the rocks.

Answer 3

SPREADING AND ATTENUATION

Question 4

These vibrations travel through the rocks in the form of

Answer 4

ELASTIC WAVES

Question 5

there are three types of waves associated with propagation of an elastic stress wave generated by an earthquake.

Answer 5

primary (P) waves, secondary (S) waves and surface waves

Question 6

These waves propagate by longitudinal or compressive action, which mean that the
ground is alternately compressed and dilated in the direction of propagation

Answer 6

PRIMARY WAVES

Question 7

are transverse or shear waves, which mean that
the ground is displaced perpendicularly to the direction of propagation

Answer 7

SECONDARY WAVES

Question 8

are tension-compression waves similar to the P-waves expect that their amplitude diminishes with distance below the surface of the ground.

Answer 8

RAYLEIGH WAVES

Question 9

are the counterpart of the “S” body waves

Answer 9

LOVE WAVES

Question 10

the rupture causing earthquakes initiates from a point

Answer 10

HYPOCENTER OR FOCUS

Question 11

point on earth’s surface diametrically opposite to the epicenter

Answer 11

ANTI-CENTER

Question 12

An imaginary line which joins the points at which the earthquake waves have arrived at the earth’s surface at the same time is called a

Answer 12

CO-SEISMAL

Question 13

The instruments measure the ground displacements and are called

Answer 13

SEISMOGRAPH

Question 14

The record obtained from a seismograph is called a

Answer 14

SEISMOGRAM

Question 15

The seismograph has three components

Answer 15

the sensor, the recorder and the timer

Question 16

The devises that measure the ground accelerations are called

Answer 16

ACCELEROMETER

Question 17

This scale is more comprehensive and describes the intensity of earthquake more precisely.

Answer 17

Mendvedev-Spoonheuer-Karnik scale (MSK 64)

Question 18

Numerous intensity scales have been developed over the last several hundred years to evaluate the effects of earthquakes, the most popular is

Answer 18

MODIFIED MERCALLI INTENSITY SCALE (MMI)

Question 19

In the Philippines, we use the __________________________ which composed of 10 increasing levels of
intensity.

Answer 19

PHIVOLCS Earthquake Intensity Scale (PEIS)

Question 20

Perceptible to people under favorable circumstances. Delicately balanced objects are disturbed slightly. Still Water in containers oscillates slowly.

Answer 20

INTENSITY I - SCARCELY PERCEPTIBLE

Question 21

Felt by few individuals at rest indoors. Hanging objects swing slightly. Still Water in containers oscillates noticeably.

Answer 21

INTENSITY II - SLIGHTLY FELT

Question 22

Felt by many people indoors especially in upper floors of buildings. Vibration is felt like one passing of a light truck. Dizziness and nausea are experienced by some people. Hanging objects swing moderately. Still water in containers oscillates moderately.

Answer 22

INTENSITY III - WEAK

Question 23

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.

Answer 23

INTENSITY IV - MODERATELY STRONG

Question 24

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.

Answer 24

INTENSITY V - STRONG

Question 25

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.

Answer 25

INTENSITY VI - VERY STRONG

Question 26

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 considerable damage. Some well-built structures are slightly damaged. Some cracks may appear on dikes, fish ponds, 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).

Answer 26

INTENSITY VII - DESTRUCTIVE

Question 27

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 mat 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 rapture may be observed. Trees are violently shaken. Water splash or stop over dikes or banks of rivers.

Answer 27

INTENSITY VIII - VERY DESTRUCTIVE

Question 28

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 spreadings and sandboils 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 on slops over dikes and banks.

Answer 28

INTENSITY IX - DEVASTATING

Question 29

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. Changes in river courses and destructive seiches in large lakes occur. Many trees are toppled, broken and uprooted.

Answer 29

INTENSITY 10 - COMPLETELY DEVASTATING

Question 30

the logarithm to the base 10 of the largest displacement of a standard seismograph

Answer 30

magnitude