# Seismic Mapping

## Activity Source:

The Society of Petroleum Engineers. Adapted with permission.

Scientists use seismic technology to map patterns of rock formations below the surface of the Earth. Different types of rocks affect sound waves. Geologists use these sound waves to locate rocks that may contain oil and/or natural gas.

You can explore this principle with a tuning fork and various rocks. Gently strike a fork against the rocks. Note variations in sounds produced by different rocks. How could scientists use this information to help map the rock layers underground? In the following activity, you will explore one way scientists find oil beneath the Earth’s surface.

For the teacher:

In a small box or opaque container, place a small balloon containing colored water (to represent oil) into layers of rock and sand. Think carefully about where to place oil reserves in this model. Putting it in the middle might be too obvious, or putting it against the side of the box might be too confusing! Place a lid securely on the box and fasten it with masking tape. Attach graph paper to the lid of the box.

## Materials

• A cardboard box or other opaque container with cardboard lid
• Sand
• Marker pens
• Graph paper
• Rock samples
• Balloon with water
• Food coloring
• Bamboo kebab skewer

## Procedure

For Students:

1. Tap on the box and listen for an area that sounds different. Use the graph paper to record the locations of areas that sound different and seem like good candidates for oil exploration.
1. Mark off divisions of 1 cm on a bamboo skewer, beginning at the bottom. This will be your probe to “drill” for oil.
1. Use the bamboo skewer to penetrate the box lid at the location where you think the oil may be located. If you hit rock, you might find it difficult to continue. Consider how drill bits are used in real drilling to churn and break rock in the path.
1. Record each probe in a chart, including at what depth (in centimeters) you “drilled” each time.
1. Continue probing until you find evidence of “oil” (the skewer will show food coloring.) At that point, your exploration is complete.
1. Optional: Have student groups create their own oil reserves model, and exchange with other groups to practice seismic mapping.
1. Discuss: What is the process of seismic mapping? What are petroleum geologists looking for when they use seismic technology? If each probe of Earth’s surface costs \$75,000, and each centimeter deep costs another \$150,000, what was the total cost of your exploration until you found oil? How would you change your exploration procedure to save money?