Earthquakes and Liquefaction

Materials / Preparation

For the demonstration, you will need:

• Metal pan, water
• sand
• smooth brick
• rubber mallet

For the lab activity, provide the following items for each group of students:

• cornstarch
• water
• shoebox or plastic box
• newspaper
• blocks of wood
• other objects that fit into the box
• paper and pencil
• local map of liquefaction areas

Visit the Earth Systems Inquiry Activity site, read and then download the activity.

For liquefaction maps, select from the following sources:

• Victoria, Canada (This is a 2.4MB file and requires Adobe Reader to open.)
• California (Click on the map under the words Quick View Download PDF Maps. For Northern California, click on the name of a city closest to where you live too the soil liquefaction map. For Southern California, click on the Go to Southern California button at the very top of the page then click on the name of a city closest to where you live to see the soil liquefaction map.)
• San Francisco Bay Area 1
• San Francisco Bay Area 2

Grouping

Groups of three or four

Teacher tips

There are two activities here – one is a demonstration, particularly helpful if you have little time or you are working with younger students. The other is a student lab. Both cover the same general principles, but the lab activity allows students to really explore the parameters in a scientific manner.

Do the labs yourself before you introduce them to your students.

Procedures

1. Start the class by asking students the meaning of the word liquefaction. Write all their answers on the board. Do not give the correct definition if it is not given, and do not acknowledge it if it is given. Tell the students that they should determine the correct definition through the lab experience.
2. Now start the lab as described at: Faultline: Liquifaction (demo) and/or Earth Systems
   Inquiry Activity (lab)
3. After the students have completed the lab or viewed the demonstration, have students discuss their findings and create a definition for liquefaction.
4. Then, ask them to go to What is Soil Liquefaction? and complete their description of what liquefaction is. This site is accessible from the Earthquake Hazards Student Web Page.
5. Discussion. Make sure that the students know the three main factors of liquefaction: Loose, unconsolidated sands or soils, Water!, Strong Shaking.
   Ask students where they might expect these features to be present (Answer: along coastlines, marshes, rivers, and areas with artificial fill).
6. Pass out the liquefaction maps which students can use to test their hypotheses. Explain that liquefaction susceptibility maps are created by determining the type of rock/soil exposed at the surface and the average depth of groundwater. In order to test their hypotheses, have students find areas with high liquefaction susceptibility (usually shown in red or dark colors). Are they close to coastlines? Do they follow creeks (these are typically shown as blue lines on the maps, but even if they are not, you can recognize them as slightly curvy, meandering zones of high liquefaction hazard)?

Resources used

Earth Systems Inquiry Activity
http://www.teachingboxes.org/catalog.jsp?id=DLESE-000-000-008-901

Victoria, Canada
http://www.teachingboxes.org/catalog.jsp?id=DLESE-000-000-008-902

Southern California
http://www.teachingboxes.org/catalog.jsp?id=DLESE-000-000-008-908

San Francisco Bay Area 1
http://www.teachingboxes.org/catalog.jsp?id=DLESE-000-000-009-349

San Francisco Bay Area 2
http://quake.usgs.gov/~dalessio/DLESE/EQ/liquefaction.html

Faultline: Liquifaction
http://www.teachingboxes.org/catalog.jsp?id=DLESE-000-000-008-910

What is Soil Liquefaction?
http://www.ce.washington.edu/~liquefaction/html/what/what1.html