Volcanoes in the United States
Look at the animated map of volcanoes in the animated National Atlas, www.nationalatlas.gov/volcano48.html. (You will need Shockwave to display this movie; you can download Shockwave at the link on this page.) Where are most of the volcanoes in the lower 48 states? Roll over the red dots to see photos and elevations of the volcanoes. As you move down the chain of mountains from north to south, is there a trend in elevations? Look at the Alaska map. How are the volcanoes arranged here? Based on your readings in this chapter, can you explain the pattern?
Where are Recent Earthquakes?
You can find out about recent earthquakes, where they were and how big they were, by looking at the USGS earthquake information page, earthquake.usgs.gov/. Click on the map to investigate recent events.
1. Describe where most recent earthquakes have occurred, either by dominant states or by mountain ranges/coastlines or other geographic features. Using what you know from this chapter about causes of earth movement and earthquakes, can you explain any of the patterns you see? Find at least one concentration of earthquakes, and try to explain the geologic processes that cause them. You might do this with a partner so that you can discuss likely explanations.
2. Now choose a map (conterminous U.S., Alaska, Hawaii, or Puerto Rico), and look at the magnitude of recent earthquakes: compare the size of squares to the magnitude numbers in the legend. What size class is most dominant? What proportion of earthquakes on your chosen map are in the largest size class?
3. Alaska is often a hot spot of earthquake activity. Find the Alaska map (you may have to back up a page or two), and zoom in on a concentration of earthquakes. How many earthquakes are off-shore? How many are on-shore?
4. Click on an earthquake in a location that is somewhat familiar to you. After you zoom in a few times, you should be redirected to some text information about that earthquake, and you may be able to find still more detailed maps. As you get closer, can you recognize features around the earthquake site? All these earthquakes occurred within the last week or less. Have you heard about these recent earthquakes in the news? Why or why not?
