Case Study: Investigating Earthquake Activity-
Predicting the Next Big One!

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Earthquake Activity

Earth is a dynamic planet. Its crust is continuously forming and deforming, constantly pushed and pulled as it moves. When strain that has built up over time is suddenly released, the crust shakes, and we call this movement an earthquake. Depending upon their strength and where they strike, earthquakes can inflict severe property damage and claim thousands of lives.

Explore recent earthquake activity by clicking the links below.
Consider the bulleted questions as you investigate earthquake activity at each site.

USGS Recent Worldwide Earthquake Activity
To explore individual earthquakes in more depth, click on the UTC Date-Time field.

• What is the magnitude of the most recent recorded earthquake?
• How many earthquakes were recorded for the last seven days?
• Of those earthquakes, how many were of a magnitude 7.0 or greater?

IRIS Seismic Monitor
Click on the map to zoom to specific regions. Click on individual earthquakes to see lists of others nearby.

• Where are earthquakes concentrated?

Where does the Earth quake?

The geographic distribution of earthquakes on Earth is not random. Due to the stresses and strains associated with a crust that is broken into plates that are moving, earthquakes are predictably concentrated along the plate boundaries and fault systems associated with the plates. Yet, knowing when an earthquake will strike any given place on Earth is not so easy to predict. This map shows earthquakes plotted in yellow against plate boundaries shown in light blue.

Image created by NASA/Goddard Space Flight Center - Scientific Visualization Studio, Smithsonian Institution, Global Change Research Project (GCRP), National Oceanic and Atmosphere Administration (NOAA), United States Geological Survey, National Science Foundation (NSF), Defense Advanced Research Projects Agency (DARPA), Dynamic Media Associates (DMA), New York Film and Animation Company, Silicon Graphics, Inc. (SGI), Hughes STX Corporation.

Predicting the Next Big One!

On a single day on Earth, thousands of earthquakes may occur, but it is the big earthquakes that are usually of interest to people. (An earthquake is considered to be big if it has a magnitude of 7.0 or greater on the Richter scale.) These quakes can cause major damage and loss of life. On average worldwide, about 18 earthquakes per year qualify as big.

Seismographs all over the Earth record earthquake activity as it takes place. When predicting where the next big earthquake might occur, seismologists look closely at areas where major earthquakes have occurred in the past, but have not occurred in the last 100 years. However, scientists can not predict the exact location, time, or magnitude of an earthquake. What they can do is identify areas where it is more likely for a big earthquake to occur sooner rather than later. In this chapter, you will examine historical earthquake distributions, monitor current earthquake activity, and try to predict where the next big earthquake will occur on Earth!