The New Childrens Encyclopedia

VOLCANOES AND EARTHQUAKES

35

EARTH

Ash clouds blast fine particles high

up into Earth’s atmosphere, where

they can affect the world’s weather

for months.

EARTHQUAKES

Earthquakes occur when two blocks of the Earth’s

crust slip past each other. The place where

this happens is called a fault.

Because the blocks do not

slide easily, a large amount of

energy is released when

they move. This ripples

away like waves on a

pond, shaking the

ground above.

O

Tsunamis are giant ocean waves

caused by a sudden movement of the

ocean floor. Sometimes colliding plates

get stuck. When they finally release, it

can trigger an earthquake, which gives the

overlying water a huge shove. The waves

grow stronger as they cross the ocean and

cause devastation when they hit land.

TSUNAMI

 ON SHAKY GROUND

When the ground shakes, buildings

and other structures may collapse.

The strength of an earthquake is

measured using the Richter scale.

This earthquake in Kobe, Japan,

measured 7.3 on the scale. It lasted

for only 20 seconds, but it made

200,000 buildings fall down.

RING OF FIRE

O

The “ring of fire” lies around the rim of

the Pacific Ocean. It is an area where a

number of crustal plates meet, resulting

in frequent volcanic and earthquake

activity. There are 452 volcanoes in the

ring, and 80 percent of the world’s

largest earthquakes occur in this area.

The epicenter is

the source of the

earthquake.

Energy wave Fault line

 BEFORE Banda Aceh in Indonesia was

close to the epicenter of the 2004 earthquake

and was the first place the tsunami struck.

 AFTER Most of the northern shore was

submerged by the tsunami. More than

230,000 people in eleven countries died

when the waves hit land.

 WORLDWIDE WAVE The tsunami

of 2004 began with an earthquake off the

coast of Indonesia. The wave was eventually

felt as far away as Iceland and Chile.

 COMPOSITE
VOLCANO These cones
rise steeply toward the
summit. They are the most
deadly type because they
usually erupt explosively.

Bangladesh

21 ⁄ 2 hours

India

2 hours

Sri Lanka

1½ hours

Indonesia

15 minutes

Malaysia

30 minutes

Epicenter