This magazine article describes how two high-magnitude earthquakes (7.6 in both instances) triggered landslides in El Salvador and Taiwan which caused extensive damage and loss of life, apart from the shaking of the earthquakes themselves. The article points out that the two areas have common features- tectonically very active, high steep slopes and deeply weathered material, that made the landslides ... Full description.

This hands-on activity demonstrates the abrasive power of glaciers carrying rocks and sand. Its purpose is to illustrate the concept that glaciers change the Earth's surface through the processes of erosion and deposition. Students construct model glaciers by freezing water with sand and pebbles at the bottom to represent the rock fragments carried by a real glacier. They then rub their 'glacier' ... Full description.

Users can choose a time in geologic history, select the link, and see what the Earth looked liked in the far distant past. Each map features a brief written description of the events occurring at that time, and a link to additional information on the geologic era or period being shown. There are also maps that show what the Earth might look like in the future, 50, 100, and 150 million years from now. ... Full description.

This isoseismal map shows shows regions of different intensities according to the Modified Mercalli Intensity Scale. These zones were defined using the felt reports from the Charlevoix-Kamouraska earthquake of February 1925, which occurred in central Quebec, Canada. Full description.

This isoseismal map shows the distribution of Modified Mercalli values compiled from questionnaires distributed after the largest shock of the January 1988 Tennant Creek earthquake, which occurred in Northern Territory, Australia. Full description.

In this exercise, students will study the three types of faults, investigate the association between faults and earthquakes, and examine the relationship between earthquakes and plate tectonics. There is a set of animations that illustrate the types of seismic waves, an exercise in which students determine the location of an earthquake epicenter using arrival times of P and S waves, and an exercise ... Full description.

In this activity, students gather data and compare the shaking intensities of the 1906 San Francsico and 1989 Loma Prieta earthquakes. They compare shaking intensity maps from the two earthquakes using the Modified Mercalli Shake Intensity, examine the lengths of fault ruptures, and examine seismograph traces from each earthquake. Links to additional information and to lesson plans that use these ... Full description.

This interactive feature provides an introduction to the theory of plate tectonics. Topics include the history of ideas on plate tectonics, some evidence that the continents were once connected to each other, what happens when plates move and collide, and a description of the internal structure of the Earth. Interactive illustrations and animated maps are included to help reinforce these concepts. Full description.

This page provides an introduction to plate tectonics for secondary students. Topics include plate motions, the layers of the Earth and oceanic versus continental plates. A set of links provides access to material on the processes of plate tectonics occuring at plate boundaries, zones of movement and instability. Full description.

This page discusses the three main forces (compression, tension, and shear) that drive deformation within the Earth. Students can click on an animation to see illustrations of each type. Links to a glossary are embedded in the text. Full description.