Seismic Waves: How Earthquakes Move Through the Earth
A member of the Virginia Task Force 1 Urban Search and Rescue Team surveys the destruction caused by a 7.0 earthquake in Port-au-Prince in January 2010, before continuing recovery efforts.Copyright 2010 Aaron Shelley, U.S. Navy http://commons.wikimedia.org/wiki/File:US_Navy_011020-N-6006S-083_A_Member_of_the_Virginia_Task_Force_1_Urban_Search_and_Rescue_Team_surveys_the_destruction_caused_by_the_recent_earthquake_in_Port-au-Prince.jpg
Students learn about the types of seismic waves produced by earthquakes and how they move through the Earth. The dangers of earthquakes are presented as well as the necessity for engineers to design structures for earthquake-prone areas that are able to withstand the forces of seismic waves. Students learn how engineers build shake tables that simulate the ground motions of the Earth caused by seismic waves in order to test the seismic performance of buildings.
Earthquake engineering focuses on protecting people and the natural and human-made environments from earthquakes by limiting seismic risk. This involves applying an understanding of seismic waves in order to create and maintain structures and urban infrastructure to perform to expectations when under duress from seismic loading due to seismic waves. A properly engineered structure does not necessarily have to be extremely strong or expensive; it has to be properly designed to withstand the seismic forces while sustaining an acceptable level of damage.
After this lesson, students should be able to:
- Describe waves using appropriate vocabulary: amplitude, crest, trough, wavelength, frequency.
- Describe the relationship between the wavelength and frequency of a wave.
- Explain the different types of seismic waves and how they move through the Earth.
- Explain the role of shake tables for engineers who design structures to withstand the motions caused by seismic waves.