Earthquakes

Question 1

How do earthquakes occur?

Answer 1

They occur when two tectonic plates slip past one another.

Question 2

What is the surface where two tectonic plates slip past each other?

Answer 2

It is called the fault or fault plane.

Question 3

What is the focus?

Answer 3

The location below the earth’s surface where the earthquake starts.

Question 4

What is the epicenter?

Answer 4

The location directly above the focus on the surface of the earth

Question 5

What are foreshocks?

Answer 5

These are smaller place earthquakes that happen in the same as the larger earthquake that follows.

Question 6

Scientists can’t tell that an earthquake is a foreshock until the ______ earthquake happens.

Answer 6

Larger

Question 7

What is the largest main earthquake called?

Answer 7

The main shock

Question 8

What are aftershocks?

Answer 8

These are smaller earthquakes that occur afterwards in the same place as the main shock.

Question 9

How long can aftershocks last?

Answer 9

Weeks, Months and even years.

Question 10

What are the two ways scientists quantify the size of earthquakes?

Answer 10

Magnitude and intensity

Question 11

What is magnitude?

Answer 11

Magnitude is a measure of the amount of energy released during an earthquake.

Question 12

What is intensity?

Answer 12

It refers to the effect of the earthquake

Question 13

What are earthquakes recorded by?

Answer 13

Instruments called seismographs

Question 14

What recordings do seismographs make?

Answer 14

Seismogram

Question 15

When was the Richter scale invented?

Answer 15

1930

Question 16

What is the Richter Scale?

Answer 16

It is used to measure the largest seismic wave on the seismogram.

Question 17

The Richter scale uses a _______ scale.

Answer 17

Logarithmic

Question 18

Explain how the Richter scale works:

Answer 18

It uses a logarithmic scale. A specific seismogram located 100km away from the epicenter of an earthquake. A wave one millimeter high on a seismogram would have a magnitude of 3 because 1000 is ten raised to the third power. In contrast, a wave ten millimeters high would have a magnitude of 4.

Question 19

What do we mean if we say the Richter scale is open-ended?

Answer 19

There is no limit to how small or large an earthquake might be.

Question 20

Before the Richter scale was invented the effects of earthquakes at different locations was _______ and ________. Intensity is measured using the modified ___________. This scale uses Roman Numerals to describe earthquake intensity. An earthquake intensity of I is generally not felt, and an intensity of XII represents total destruction of buildings.

Answer 20

Observed
Recorded
Mercalli Scale