Earthquakes

Earthquakes

Social Studies

7th Grade

First some easy questions

Multiple Choice

What theory refers to the movement of Earth's plates

• Tectonic plates

• Continental drifting

• Plates shaking

• Tectonical movement

Multiple Choice

What causes Earth's plates to move?

• Convection in the crust and subduction in the core

• Convection currents in the mantle

• Earthquakes

• Heat from the Inner Core

Multiple Choice

Under sea mountain ranges are called

• Deep sea trenches

• Oceanic mountains

• Acuatic mountains

• Mid-ocean ridges

Multiple Choice

What type of plate boundaries occurs at mountain ranges?

• Divergent

• Transform fault

• Convergent

Multiple Choice

How is it called this landform formed by divergent boundaries?

• Trenches

• Rift Valley

• Fault

• Mountain ranges

What is an earthquake?

• An earthquake is the movement of Earth’s crust resulting from the release of built-up potential energy between two stuck lithospheric plates

Parts of an earthquake

• The point below the surface where the rock breaks is called the earthquake focus

•  As soon as the rock breaks, there is movement along the broken surface causing a split in the surface called a fault

• The epicenter is the point on the surface right above the focus

Seismic waves

• Waves that carry energy of an earthquake away from the focus

• Seismic waves that travel through Earth’s interior are called body waves. The two main kinds of body waves are P-waves and S-waves

• Waves on the surface, or body waves that reach the surface, are called surface waves

• P-waves travel through solids and liquids, compressing and expanding the materials they pass through.

• S-waves only travel through solids and temporarly change the shape.

•  Surface waves reach the surface. They are slower than body waves, but they are the waves that cause the most damage.

Multiple Choice

A point on Earth’s surface right above the focus of an earthquake.

• Epicenter

• Heliocenter

• Hipocenter

• Staples center

Multiple Choice

A region on Earth’s surface that is split into two pieces.

• Fail

• Fault

• Fake

Multiple Choice

Which type of seismic waves cause the most damage?

• P-waves

• S-waves

• Surface waves

• Tsunami waves

Where do earthquakes occur?

• Earthquakes commonly occur at the boundaries of lithospheric plates. Earthquakes occur less commonly at faults that are inside plate boundaries

• Millions of earthquakes happen every year. Not all of them are recorded because most are too weak to be felt.

Measuring earthquakes

• Seismometer - device that measures intensity of earthquakes. Intensity is the strength of the shaking motion

• There are two related measurements taken during and after an earthquake—the energy released and the damage caused.

•  The Richter scale rates earthquakes according to the size of the seismic waves recorded on a seismograph

• Aproximately 15 earthquakes in the magnitude 7 range and one earthquake magnitude 8.0 or greater are expected each year

The Mercalli Intensity scale has 12 descriptive categories. Each category is a rating of the damage suffered by buildings, the ground, and people. 

Multiple Choice

What event happens when there is a sudden, violent shaking of tectonic plates?

• Hurricane

• Earthquake

• Thunderstorm

Multiple Choice

When scientists map the location of earthquakes, where do they find that most earthquakes happen?

• Middle of tectonic plates

• Only near mountains and volcanos

• In the mantle

• At plate boundaries

Multiple Choice

Why aren't all earthquakes recorded?

• Some happen too far underground

• Some are too weak to be felt

• Some happen too much far way from cities

• Happen under the mantle

Multiple Choice

Which scale measures the magnitude, or size, of an earthquake?

• Richter

• Mercalli

Multiple Choice

What device is used to measure the intensity of an earthquake?

• Shakemeter

• Termometer

• Movemeter

• Seismometer