Visit the website of Volcano World at the University of North Dakota (USA). Volcano World is among the premier sites on the Internet to obtain information about volcanoes around the world.

Not only can you search their archive for images of your favorite volcano, they also have a wealth of information about volcanic processes and a list of current volcanic eruptions.

For this exercise, you will learn about the greatest single volcanic eruption of the last 2 million years explore a method to determine how much material it erupted.

1. Go to the Volcano World website and familiarize yourself with this marvelous resource of information about the world' volcanoes.

2. Locate the "Volcano Name" function, click the link, and scroll down the page until you find "Toba".

3. Once the pages have loaded, read about the amazing Toba eruption approximately 75,000 years ago. Examine the images of the Toba caldera in Indonesia and study what is known about this remarkable volcanic event.

4. Pay special attention to the section that describes the quantity of material ejected from the volcano during its cataclysmic eruption. The total quantity of material sounds impressive, especially when compared to other well-known historic eruptions - but just how much material is this?

5. Go to www.encyclopedia.com to determine the area (in square kilometers) of your state, province, or country. Once at www.ecyclopedia.com, enter the name of your state, province, or country and look for information on its area (usually under "geography").

a. Next, attempt to determine how deep (in meters) the erupted material from Toba would be if all of it fell across your area by dividing the volume (2,800 cubic kilometers) by your figure for area (square kilometers). The answer you obtain is in kilometers. How many meters is this?

b. To convert your thickness to meters, simply multiply by 1000 (because there are 1000 m in 1 kilometer).

c. Note that this number assumes the material falling across your area from Toba had 0% porosity. What would the thickness be if it accumulated with 50% porosity? How thick with 75% porosity?

d. Hopefully, this exercise gives you a greater appreciation for the magnitude of the Toba eruption 75,000 years ago.