Seismology

Seismic Waves and Their Effects

4th Grade

Scientists observe how wave energy travels along Earth's surface. 

During an earthquake, energy is released into the Earth as seismic waves.

Multiple Choice

True or False: Energy is released during an earthquake.

• True

• False

Forces applied by one large rock mass on another cause stress in Earth's crust. 

Over time, as more force by rock masses is applied, the rocks bend and begin to build up stored energy. If more stress builds up, the large rock mass can break or slip along a fault.

Focus

Seismic waves travel outward in all directions from the earthquake's underground origin, or its focus.

Epicenter

 The point on the Earth's surface directly above the focus is the earthquake's epicenter.

Multiple Choice

Seismic waves travel outward from the:

• epicenter

• fault line

• focus

Seismic Waves

• Seismic waves can be destructive.  

• The waves that travel along the Earth's surface are the most destructive.

• Surface wave energy is always strongest at the earthquake epicenter.

Seismographs

• Scientists can use seismic waves to map locations of earthquake epicenters. 

• Scientists measure seismic waves on instruments called seismographs.

• The arrival time and strength of each kind of seismic wave is recorded by the seismograph onto readings called seismograms.

Multiple Choice

True or False: A seismograph measures the strength and location of a volcano.

• True

• False

Richter Scale

• Scientists measure the strength of an earthquake using something called the Richter scale.

• The strength of the earthquake is given a number from 0 to 10. 

• The larger the number, the stronger and more destructive the earthquake is.

Multiple Choice

Choose the richter scale numbers that would indicate a major earthquake causing serious damage.

• 1.0-3.5

• 7.0-7.9+

• In the 100s

• Under 6.0

Thank you!

Tomorrow you will use this knowledge to complete your Study Island assignment. Good luck!