Answer Key - Assignment 11 Volcanism

1. According to the video, where are the vast majority of the Earth's volcanoes located? What percentage? (2 points)

80 % of volcanoes are beneath the surface of the oceans

2. Describe how the eruption of the Hawaiian volcano Kilauea differs from the 1980 eruption of Mount St Helens. (3 points)

Mt Kilauea is a shield volcano that has very fluid lava that can be outpaced at a "brisk walk". It is not a violent erupting volcano. Mt St Helens is a composite volcano. It exploded violently.

3. The Japanese volcano, Sakurajima erupts up to how many times per year? (1 point)

Approximately 400 times per year

4. In the 1815 eruption of Mt Tambora in Indonesia, how many cubic miles of the mountain were sent into the atmosphere? How did this eruption affect climate? (3 points)

20 cubic miles of Earth were sent into the atmosphere where they diminished solar radiation, causing cold summers (the year without a summer). Crop failure and starvation followed

5. Based on what you saw and learned in this movie, describe a pyroclastic flow. (2 points)

When lava is too thick to flow it may form a bulge which eventually collapses sending hot rock, ash and gas down the mountainside at high speeds.

6.  Who were the famous volcanologists killed by the Mount Unzen eruption? What specifically killed them? (2 points)

Maurice and Katia Krafft were killed by a pyroclastic flow.

7.  What is unique about the lave emitted by Mt Lengai in Tanzania? (1 point)

Mt Lengai's lava is only about 500°F, much cooler than most lavas. The lava emerges and is black, it cools to white and it glows red at night.

8. In the 1985 eruption of the Columbian volcano, Nevada de Ruiz, 23,000 people were killed by what specifically?  (1 point)

People were killed by a volcanic mudflow caused by the eruption melting glaciers on the volcanoes flank (this type of mudflow is called a lahar)

9. The 1991 eruption of Mt Pinatubo in the Philippines was the largest volcanic eruption of the 20th century. What atmospheric event coincided with the eruption? (1 point)

The Philippines was struck by a major typhoon at the same time the volcano erupted.