Volcanoes and Earthquakes Text P 326-331
Read text P. 326 – 328 and answer Q 1-3. If this is already completed;
Read P 329 – 330 and do the following
1. What is a ‘seismic wave’ ?
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2. Scientists measure the strength of earthquakes by using a logarithmic scale called
the Richter scale. Read the following and then answer the questions.
Richter Scale
The Richter scale grows by powers of 10. An increase of 1 point means the strength of a
quake is 10 times greater than the level before it. This is called a logarithmic scale. Here's
how it works:
An earthquake registering 2.0 on the Richter scale is 10 times stronger than a quake
registering 1.0. A quake registering 3.0 is 10 X 10 or 100 times stronger than a quake
registering 1.0. An earthquake registering 4.0 is 10 X 10 X 10 or 1,000 times greater than
1.0 and so on.
Below is the Richter scale showing the damage caused at each magnitude.
1.0 — Earthquakes this small happen below ground. You can't feel them.
2.0 — Trees sway. Small ponds ripple. Doors swing slowly. But you can't tell an earthquake is to blame.
3.0 — You may notice this quake if you are sitting still, or upstairs in a house. A hanging object, like a
model airplane, may swing.
4.0 — Buildings shake a little. It feels like a truck is passing by your house.
5.0 — If you are in a car, it may rock. Glasses and dishes may rattle. Windows may break.
6.0 — Pictures can fall off walls. Furniture moves. In some buildings, walls may crack.
7.0 — It is hard to keep your balance. The ground cracks. Roads shake. Weak buildings fall down. Other
buildings are badly damaged.
8.0 — Very few buildings stay up. Bridges fall down. Underground pipes burst. Railroad rails bend. Large
rocks move. Smaller objects are tossed into the air. Some objects are swallowed up by the earth.
9.0 — Causes complete devastation and large-scale loss of life.
Question 1. What was the magnitude of the earthquake that hit Haiti In January of 2010?
Question 2. If the building is shaking a little and it feels like a truck is passing close by,
what is the magnitude of the earthquake?
3. Use the information on P. 330, Table 6 to fill in the missing information in the table
below.
Tectonic
plate
movement
Illustration
Characteristics of
earthquakes triggered by
this movement
4. What is a Tsunami and what causes them?
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Read P 331 and answer the questions 1-3 in the space below.
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