1. Volcanoes
Mt. Etna, Sicily, Italy August 5, 1997 with city lights.

2. Ring of Fire
The Ring of Fire coincides with the edges of one of the world’s main tectonic plates.
The Ring of Fire has frequent earthquakes and volcanic eruptions.

3. Mount Pinatubo
Mount Pinatubo prior to the 1991 eruption (elevation 5725 feet).

4. The Eruption of 1991
June 12-15, 1991 brought eruptions of Pinatubo to the island of Luzon.
From eruption columns 18 km wide and up to 30 km high, 5 billion cubic meters of pyroclastic and ash poured out.
20 to 30 megatons of sulfur dioxide and aerosols were also released into the air.

5. Satellite images of the volcanic cloud, over 9 days, showing the dispersal of the sulfur dioxide plume.

6. Mount St. Helens
Before

7. May 18, 1980

8. Mount St. Helens early on May 18, 1980
and C. show the development of the debris avalanche, the beginning of the vertical eruption and lateral blast. The bulge block slid first followed by the graben block. (in 1st 30 sec)
D. The summit black slid, and the lateral blast was completed. The vertical eruption is in full fury. (in 1st minute)

9. (on left): The extent of the lateral blast
(on right): What appears to be blown grass, are actually large tress, some over 100 feet tall, flatten by the lateral blast.

10. Ash Fallout
Distribution of ash fallout from the May 18, 1980 blast.

11. Results of May 18, 1980
(on left): Geologic map showing the impacts and deposits.
(on right): Mud flow damaged house.

12. Mount St. Helens
After