Modified Mercalli intensity scale

This task is about using scale and information to measure the damage caused by earthquakes.

The Modified Mercalli intensity scale measures the actual effect an earthquake has on people, buildings, and the environment.

Magnitude		Effect
I		Only felt by a very few.
II		Felt by persons at rest.
III		Felt indoors. Some hanging objects swing.
IV		Vibration like heavy traffic passing, or like the jolt of a heavy object falling.
V		Generally felt outside. Most sleepers awakened. Small, unstable objects move, some glassware and crockery broken.
VI		Felt by all. Difficulty in walking steadily. Objects fall from shelves. Slight damage to badly constructed buildings.
VII		General alarm. Difficulty in standing. Some damage to buildings not designed to withstand earthquakes. Furniture moves. Unreinforced chimneys, roofing tiles and water tanks broken.
VIII		Alarm may approach panic. Steering of motorcars greatly affected. Some damage to earthquake-resistant buildings. Serious damage to less well-designed building types. Monuments and elevated tanks brought down.
IX		Heavy damage to buildings and bridges. Houses not secured to foundations shifted off. Landslides widespread on steep slopes. Cracking of ground conspicuous.
X		Severe damage to many buildings and bridges, even those of most recent design.

a) Read the following descriptions of peoples' experiences of earthquakes,

and use the Modified Mercalli scale to work out there intensity.

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The epicentre of an earthquake can be located by measuring the time between the arrival of P and S waves from the earthquake epicentre. If you count the time in seconds between these two waves and then multiply this by 8 it will tell you how far away in kilometres the epicentre was.

b) Two friends were talking on the telephone when an earthquake occurred. Sally who lived in Edgeton counted 5 seconds between the waves,

while Atawhai who lived in Haltsdon counted 6.5 seconds.

b) Two friends were talking on the telephone when an earthquake occurred. Sally who lived in Edgeton counted 5 seconds between the waves,

while Atawhai who lived in Haltsdon counted 6.5 seconds.

i) How far away was each person from the epicentre?

Sally kilometres

Atawhai kilometres

Question 1Change answer

c) Here is some data about two different earthquakes.

A	01/08/00 at 00:30 (30 minutes after midnight). 540 km south of the Fiji islands with a magnitude of 4.6, and 500 km deep.
B	01/08/00 at 21:33 (9:33 p.m. in the evening). 170 km northwest of Vancouver City, Canada with a magnitude of 4.8, and 10 km deep.

c) Here is some data about two different earthquakes.

A	01/08/00 at 00:30 (30 minutes after midnight). 540 km south of the Fiji islands with a magnitude of 4.6, and 500 km deep.
B	01/08/00 at 21:33 (9:33 p.m. in the evening). 170 km northwest of Vancouver City, Canada with a magnitude of 4.8, and 10 km deep.

Which earthquake would have been likely to cause the most damage? AB

Give three reasons why this earthquake would be likely to cause more damage.

			Y10 (11/2000)
a)		A: IV B: VII (accepted VI) C: VIII	easy easy very difficult
b)	i) ii)	40 km 52 km South/South East/East	easy easy
c)		B and Because the earthquake was not as deep. Because the earthquake was of greater magnitude. Because the earthquake was centred closer to a built up area/land.	3 correct – difficult 2 correct – easy 1 correct – easy

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Modified Mercalli intensity scale

Modified Mercalli intensity scale

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