Joseph Keller, age 10, of South St. Paul, Minnesota, for his question:

Which is the world's largest volcano?

Mount Guallatiri in the Andes Mountains of Chile erupted in 1959. It stands 19,882 feet above sea level    which makes it the tallest active volcano in the world. Mount Aconcaugua in the Andes of Argentina stands 22,834 feet, but its erupting days are over, it is therefore considered extinct    the world's highest extinct volcano. Mount Kilimanjaro in Africa rates as the world's tallest dormant volcano. It is a sleeping type which may or may not erupt again.

The world's most massive volcanos erupted from the bottom of the sea and piled up their lava to build islands, high and dry above the waters. The largest of these is Hawaii's Mauna Loa. This very active volcano stands 13,680 feet above sea level. However, the part above the water rests on a mighty volcanic mountain sitting on the floor of the Pacific Ocean. The seabed is almost four miles deep. If we add this to the part above sea level, we must consider Mauna Loa as the world's largest volcano.