E. VOLCANOES AND CLIMATE 82

Volcanic ash injected into the stratosphere during especially explosive eruptions can stay airborne for months and can reflect sunlight. Also, tiny drops of sulfuric acid effectively absorb sunlight. Both can cause average annual temperature to drop & pretty sunsets.

Volcano

Year

Temp. drop

Pinatubo

1991

~0.4°C

El Chichon

1982

~0.4°C

Mount St. Helens

1980

0.1°C

Krakatau

1883

0.6°C - vivid sunsets in N.E. and London

Tambora

1815

>1°C - "Year without summer".

 

LARGEST EXPLOSIVE VOLCANIC ERUPTIONS

SINCE AD 1400

YEAR

VOLCANO

VEI *

1452

~1580

1600

1641

~1660

1815

1883

1902

1912

1991

Kuwae, Vanuatu, SW Pacific

Billy Mitchell, Bougainville, SW Pacific

Huaynaputina, Peru

Parker, Philippines

Long Island, New Guinea

Tambora, SumbawaIs., Indonesia

Krakatau, Sunda Strait, Indonesia

Santa Maria, Guatemala

Novarupta, Alaska

Pinatubo, Philippines

6

6

6

6

6

7

6

6

6

6

* VEI is the Volcanic Explosivity Index, a 0 to 8 index of increasing explosivity (each unit representing an increase of about 10x) based on volume of explosive products, eruptive cloud height, eruption duration, and other measures.

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