Answer the following Questions for Review
(Chapter 7, page 146)
What products of a volcano can kill large numbers of people long after an eruption has ceased? How? (1)
Pyroclastic flows, lahars, ash falls, tsunami initiated by eruptions. In some cases, the high causalities were a result of misjudgments of politically motivated decisions by authorities. Which is more dangerous, a lava flow or a pyroclastic flow? Why? (2) Pyroclastic flows are more dangerous because they are fast moving and destructive. Lava flows are slow. How can you tell whether a plume rising from a stirring volcano contains new magma that may soon erupt? (3) If a plume rising is a stirring volcano contains new magma that may soon erupt it will be dark. What product of a volcanic eruption causes a widespread drop in temperature and possible crop failures? (4) Volcanic ash.
What commonly triggers mudflows? (6) Mudflows are triggered when volcano covered with snow is erupted or when it is raining during eruption. Why is erupting volcanic ash dangerous to jet aircraft? (7) Erupting volcanic ash is dangerous to jet aircraft because it is made up with glass particles and pulverized rock which can go ten thousands of feed into the air. If a pyroclastic flow approaches you from across a 1 km wide lake, are you likely to be safe? Explain why or why not. (8) No you are likely not safe, pyroclastic flow can cross many things such as a lake and it will
reach you. What characteristics of an old ash fall tuff will permit you to distinguish it from an old pyroclastic flow tuff? (9) Ash fall is very layered and pyroclastic flow tuff is unlayered. Ash tuff deposits spread evenly and pyroclastic flow tuff is thick and not spread evenly. Which erupting volcanic hazards kills more people than anything else? What accounts for this danger? (10) The erupting volcanic hazard that kills the most people is pyroclastic flow because it is fast and can go to and cross many different areas.
What evidence do scientists use to decide whether a volcano may be getting ready to erupt? (13) Harmonic tremors, tiltmeters, earthquakes, paleovolcanology evidence, and plumes.
