EARTHQUAKE HAZARDS

Question 1

is a natural event feared by many, even by those who have not recalled any
experience of it or its effects.

Answer 1

Earthquake

Question 2

and earthquake are usually used
synonymously because people perceive earthquake often when the ground below
shakes without warning.

Answer 2

Ground shaking

Question 3

is a phenomenon caused by the sudden and rapid movement of large
volumes of rock along fractures on the surface of the earth called faults.

Answer 3

earthquake

Question 4

rock along fractures on the surface of the earth called

Answer 4

faults

Question 5

The outermost
shell of the earth, which includes the crust and the uppermost mantle, consists of

Answer 5

tectonic plates.

Question 6

These are massive and irregularly shaped slabs of rock. Due to their
roughness, the edges of these plates get stuck while the plates continue moving.

Answer 6

tectonic plates.

Question 7

energy stored in the rocks is released in the form of

Answer 7

seismic waves.

Question 8

two types of seismic waves:

Answer 8

body waves and surface waves.

Question 9

are seismic waves that travel through the interior of the earth.

Answer 9

Body waves

Question 10

the first waves that reach the surface of the
earth and make the ground shake. They move the ground back and
forth along the direction they are traveling. The shaking from P

waves is light or sometimes not felt.

Answer 10

Primary (P) waves

Question 11

are body waves that vibrate perpendicular to
their propagation direction, producing an up and down motion. They
move slower but shake the ground more strongly than P waves.

Answer 11

Secondary (S) waves

Question 13

are waves that are trapped near the surface.

Answer 13

Surface waves

Question 14

are
surface waves that have a horizontal motion perpendicular to the direction
they are traveling.

Answer 14

Love waves

Question 15

shake the ground in a rotational manner

with no transverse motion.

Answer 15

Rayleigh waves

Question 16

The severity of an earthquake is measured based on the energy it
releases, or its

Answer 16

magnitude,

Question 17

its effects on people and man-made

structures, or what we call

Answer 17

intensity.

Question 18

is the visible breaking and displacement of the Earth’s surface along the trace of a fault. It may
be a vertical movement, a lateral movement, or a combination of both, depending on the type of fault generating

Answer 18

Ground rupture

Question 19

faults that are vertical or near-vertical faults that displace rock horizontally.

Answer 19

Strike-slip faults

Question 20

If the block opposite you when
looking across a fault moves to the left, it is a

Answer 20

a sinistral (or left-lateral) fault.

Question 21

fault. If the block moves to the right, it is a

Answer 21

dextral (or right-lateral) fault.

Question 22

Reverse or thrust faults are faults which move the hanging wall up. These faults are

Answer 22

dip-slip

faults,

Question 23

causes a vertical displacement of the ground.

Answer 23

dip-slip

faults,

Question 24

cases wherein water rising from the ground as the ground shakes.
Sometimes, witnesses would describe the ground seemingly act like a liquid
during an earthquake.

Answer 24

liquefaction.

Question 25

occurs when the ground loses stiffness and behaves like liquid in response to earthquakes.

Answer 25

Liquefaction

Question 26

wherein the sediments are compressed and fluids in the pore spaces are squeezed out.

Answer 26

compaction,

Question 27

out. As a result of the decrease in the spaces between grains, the pore water pressure increases. When the pore water pressure is equal to the weight of the overlying material causes ---

Answer 27

liquefaction

Question 28

or more buildings in a certain area contributes to the weight of the sediments.

Answer 28

Denser infrastructure

Question 29

Loosely-packed, saturated sediments are especially vulnerable to this earthquake hazard. Most urban communities are built upon such materials.