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PART FOUR: QUESTIONS 16 - 20
Read the text below.
Match the questions (B - J) with the paragraphs (16 - 20) in the table
below.
(0) has been done for you as an example.
There are four extra questions. Do not use them.
(0)
A
Scotland and northern England were probably hit by a giant wave 80,000
years ago. The cause was an underwater landslide off Norway when silt
from the last Ice Age went tumbling down the continental shelf. At least
two major quakes have originated in the Dover Straits. The last big one
in 1580, generated a tsunami that inundated Boulogne and Dover and
sank dozens of boats. Some geologist believe the Channel is overdue
for another quake.
(16) _____________________
The Earth is not as solid as it seems. Its surface is made up of about 13 major
“tectonic” plates that float on the semi-molten rock beneath. Where these
plates meet, they grind together, creating earthquakes. When the earthquake
is beneath an ocean it can cause a tsunami.
(17) _____________________
The biggest earthquakes occur at plate boundaries where the Earth’s crust is
being forced down (subducted) into the planet’s molten core. One of the most
active boundaries is around the massive Pacific Plate, commonly referred to
as the Pacific Ring of Fire.
If we could pull a plug and drain Pacific Ocean, we would see and amazing
sight: a number of narrow, curving trenches thousands of miles long and up to
six miles deep, cutting into the ocean floor. These trenches are where
subduction is happening. The Boxing Day quake started in a similar trench off
Sumatra.
(18) _______________________
During certain types of submarine earthquake the seabed is jerked violently
upwards – possibly by more than 40ft – in a split second. The movement
displaces billions of tons of water, which is forced above the surrounding
water. This is the start of the tsunami. As the water falls back it splits into two
waves, each roughly half the height of the original. One hurtles out to the
deep ocean while the other heads toward while the other heads towards the
coastline.
(19) _________________________
After the wave comes the trough where the sea level drops below normal and
the water dumped on land pours back to the sea, This is when much of the
damage is done as people are battered by debris and sucked out to sea.
Even worse, tsunamis seldom come in ones. The second or third wave is
usually the biggest, and some tsunamis have divided into seven or more
waves. Tsunamis can generate “edge waves” that that travel back and forth
parallel to the shore or strike it later. Beaches can remain hazardous for
several hours after the first tsunami has hit.
(20) ___________________________
About 500,000, but most are undetectable except with sensitive instruments.
About 100,000 can be felt and about 100 cause damage. In 2004 there were
15 earthquakes of magnitude 7 or above, including the Boxing Day disaster,
which was 9.
A
B
C
D
E
F
G
H
I
J
(0)
Is Britain at risk of tsunami?
How can people in quake zones be protected?
How do earthquakes cause tsunamis?
How fast can a tsunami move?
What follows a tsunami?
Where do earthquakes happen?
How do earthquakes happen?
What was the biggest known earthquake?
How many earthquakes are there each year?
Can we predict earthquakes and tsunamis?
A
(16)
(17)
(18)
(19)
(20)
Now turn over the page for PART FIVE.
Key:
PART FOUR
(0)
(16)
(17)
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A
G
F
C
E
I