Volcano Statistics

prepared by

Bill Leeman

Characteristics of common magma types

Composition

(SiO2)

Low Silica

(<53%)

Medium Silica

(53-66%)

High Silica

(>66%)

Common name
(intrusive equivalent)

basalt
(gabbro)

andesite - dacite
(diorite-tonalite)

rhyolite
(granite)

Color

dark green, gray, or black

gray, green

white, tan, pink

Viscosity ('dry')#

fluid

intermediate

viscous

Typical volcanoes

shield, cinder cone, rift

stratovolcano, cinder cone

stratovolcano
# Note that viscosity will decrease with increasing water content

 

Types of eruptions

Variety

Typical products

or effects

Volume

Violence

Typical Volcano Type

Hawaiian

(Kilauea, 1983)

Basaltic lavas

large

low

shield

Icelandic

(Laki, 1783)

Basalt sheet flows

huge

none

shield

flood basalt

Strombolian

(Paracutin, 1943)

Basaltic lava & cinders

moderate

moderate

composite

cinder cone

Vesuvian

(Ruiz, 1985)

Intermediate ash

moderate

high

composite

Plinian

(Vesuvius, 79 AD)

Rhyolite to andesite

ash tephra, pyroclastic flows

large

very high

composite

Cataclysmic

(Krakatau, 1883)

Rhyolite ash, pumice, & ash flows

huge

very high

composite

Phreatic

(Kilauea, 1924)

steam & fragmented

rocks

small

small

maar, shield, composite

 

Sizes of selected eruptions

Examples

Volume of magma (km3)

Energy (ergs * 10^22)

Explosivity (VEI)

Santorini, 1628 BC

60

90000

6

Crater Lake, 4650 BC

60

60000

6

Tambora, 1815

50

42000

7

Katmai, 1912

14

20000

6

Laki, 1783

13

86000

4

Krakatau, 1883

6

5000

6

Coseguina, 1835

5

5000

5

Vesuvius, 79 AD

3

2500

5

Bezymianny, 1955-6

3

2200

5

Paricutin, 1943-52

1.6

2800

3

Mauna Loa, 1950

0.5

1400

0

Mt. Saint Helens

0.4

100

5

Kilauea, 1959-60

0.2

500

2

Kilauea, 1952

0.6

180

0

Taal, 1965

0.03

10

4

Bikini A-bomb test

NA

<1

NA