Reading Assignments

A lahar exiting the Mount St. Helens caldera after a small eruption in 1982. The lahar eventually flowed into the Cowlitz River, 50 miles downstream.


  • Volcanoes are covered in Chapter 6 of your textbook. This chapter concentrates on an appreciation of the volcanic problem, types of volcanoes, volcanic hazards and eruption prediction. You will also be reading from the United States Geological Survey's (USGS) "Volcano Hazards" website. Please be aware that some of the terminology is different between these two reading sources. Do not let this bother you, sometimes geologists working in different areas use different terms for the same process or material. The Volcanic Hazards Assessment that you will do as a part of this lesson will use the USGS terminology. When you take the end-of-lesson quiz, you should know both sets of terminology.


  • Volcanic Hazards:   An introduction to volcanic hazards from the experts - the United States Geological Survey (USGS). You should read and learn about each of these featured hazards: tephra, lahars, lava flows, pyroclastic flows, landslides, and gases. This site has some of the best photos and illustrations that you will find on these subjects. This reading is very important because you will use it to complete one of your most challenging activities - the volcanic hazards assessment. You will need to know what these hazards are, what causes them, the types of threats they present, and how to determine the areas at risk.

  • Monitoring Volcanoes:   What do geologists watch for to determine when a volcano is likely to erupt? The USGS has an excellent record for predicting when volcanoes will erupt, the areas that will be affected, and how communities should respond to a volcanic threat. This site will explain how they use hydrology, ground deformation, seismicity, gas, and remote sensing to predict eruptions. You should read the introduction page for each of these topics.

  • Volcano World   "Volcano World is the most comprehensive volcano site on the world wide web. It would take several days of continuous reading to see everything at this extensive site. Your visit to this site now is only to see what is there. You may decide to use it when you are doing research to solve the volcanic hazards assessment. The site has a search engine to locate the topics that you might need.

  • Mount St. Helens: A General Slide Set   "An album of USGS photos that document the 1980 eruption - the most powerful in the recorded history of the 48 states!. This site will give you a real appreciation of what the eruption effects were like! The photos on this site are excellent and well worth the trouble of clicking them up individually."

The photo at the top of this page was taken by T. J. Casadevall of the United States Geologcial Survey and is part of a collection that documents the 1980 eruption of Mount St. Helens.