This demonstration uses a gyroscope (a bicycle wheel works well), string, and a turntable (optional) to show how the equatorial bulge of Earth causes precession. By balancing the spinning bicycle wheel on one hand, and pulling a string attached to the top axle with the other, the axis of the wheel traces out a circle (precesses). The site also explains how the moment of inertia is related to torque ... Full description.

This tutorial provides information on the four types of wave motion seen in earthquakes (S, P, Love, and Rayleigh waves). A table accompanied by text describes their particle motion, typical veolcity, and other characteristics. The four animations show a rectangular block of material with outlined with grid lines and a filled-in grid square to highlight the particle motion and direction of propagation. ... Full description.

In this activity, students examine a seismogram display called a seismic record section in which each trace is a seismogram recorded at a specific seismograph station. The seismograms are plotted according to the distance (in degrees, geocentric angle) from the earthquake location and time from the earthquake origin. The traces are of the vertical component of ground motion, and have been filtered ... Full description.

This set of animations, accompanied by an audio narrative, shows the four types of wave motion seen in an earthquake: P waves, S waves, Love waves, and Rayleigh waves. A brief written narrative and a set of study questions are also included. Full description.

This web site provides a general introduction to elastic rebound theory. An animation shows how the earth is gradually distorted about the fault, in response to distant forces, eventually leading to sudden slip or displacement along the fault--what we call an earthquake. Full description.

In this activity, students use magnetic field data and a map of the ocean floor around Iceland to observe how the direction of magnetization of the ocean floor varies. This links the magnetization of rocks with the theory of tectonic plates. As students complete the worksheet they will discover that the magnetic field of the Earth has flipped (the N pole becoming the S pole, and vice versa) many times ... Full description.

This lesson provides a good example of how models change over time as our understanding of the Earth system improves with more detailed observations. Students work in teams to investigate two possible models of the Earth, a simple, homogeneous interior and a layered Earth. They will use calculations and create a graph from data gathered from a model of Earth?s interior and using data from the Rapid ... Full description.

This participatory demonstration of the influence of rigidity on the speed of seismic waves helps students understand the relationship between the speeds of seismic P and S waves and the rigidity (the resistance to shear deformation) and incompressibility (resistance to compression) of the medium. The demonstration requires only a watch or stopwatch. To create the waves, students stand side-to-side ... Full description.

This is the homepage of the Marine Seismic Data Center (MSDC) of the University of Texas Institute for Geophysics (UTIG). MSDC's purpose is to organize seismic reflection and refraction data into a modern relational database management system accessible through the Internet. The web site provides access to metadata, SEG-Y (seismic shot record conversion) files, navigation files, seismic profile images, ... Full description.

This demonstration of the magnetic field lines of Earth uses a bar magnet, iron filings, and a compass. The site explains how to measure the magnetic field of the Earth by measuring the direction a compass points from various points on the surface. There is also an explanation of why the north magnetic pole on Earth is actually, by definition, the south pole of a magnet. Full description.