History of volcanoes, volcanology

1
Volcanoes for Beginners
History of volcanoes, volcanology Mythology-
Vulcan, Pele, Chuginadak Beginnings of the
science From down below to in the air Types of
volcanoes Anatomy of a volcano Types of
eruptions
2
The History of Volcanology Mythology
Hephaestus the Greek god of fire
Though cast from Olympus at birth, he became the
smith of the gods. A creator as well as a
destroyer.
3
The History of Volcanology Mythology
Hephaestus had a Roman name Vulcan
His forge was thought to lie either at the
Solfatara near Mt. Vesuvius, or more likely at
the Eolian Island named for him
Vulcano
Volcano
4
The History of Volcanology Mythology
Pele The Hawaiian goddess of fire
Daughter of the Earth Mother, Haumea, she fled
the wrath of her sister, Namaka o Kahai. She
moved eastward, creating new land, but pushing
back the sea in the process.
5
The History of Volcanology Mythology
Pele The Hawaiian goddess of fire
She moved eastward, settling in hale mau mau as
her home.
6
The History of Volcanology Mythology
Chuginadak The Unangan goddess of fire
The Aleutian Islands are home to many volcanoes.
Chuginadak, the goddess of fire, is said to have
thrown the first man and woman from the summit of
her mountain into the sea.
7
The History of Volcanology Mythology
Chuginadak The Unangan goddess of fire
Much of the Unangan culture was lost through
invasion and war. Today Cleveland volcano
remains a holy place for the Unangan people.
8
The History of Volcanology Science
The modern science of volcanology has its roots
in mythology, and grew from superstition, trial
and grievious error into the science we have
today.
9
The History of Volcanology Science
Aristotle may have been the first
volcanologist. Many of the terms he used to
describe volcanoes are in use today. -crater -te
phra
10
The History of Volcanology Science
Progress in the science was invariable driven by
observed eruptions. This is still true
today. At Vesuvius in AD92, Pompei and
Herculaneum were destroyed.
11
The History of Volcanology Science
Politics and religion were not always friends of
the science. The dark ages set all geoscience
back.
12
The History of Volcanology Science
The first volcano observatory was Osservatorio
Vesuviano in Naples, Italy. It focused on
recording the activity and providing warnings to
the populace at Mount Vesuvius.
13
The History of Volcanology Science
The eruption of Montagne Pelée in 1902 on the
Isle of Martinique cost 29,000 lives. This
triggered more advances, and La Croixs classic
work. Here glowing clouds or nuee ardente were
observed and described scientifically for the
first time.
14
The History of Volcanology Science
With Thomas Jagger and the founding of the
Hawaiian Volcano Observatory, the modern age of
volcanology began with the goal no more
abandoned or buried cities
15
The History of Volcanology Science
The eruptions of Mount St. Helens, Pinatubo and
others have driven the science to focus on
prediction of eruptions.
16
The History of Volcanology Science
Today the Alaska Volcano Observatory is
recognized by many as the world leader in
volcanology. AVO is the first observatory to use
infrared imaging in its day to day operations.
17
Modern Volcanology
Volcanology is a relatively young science
compared to physics or math, and borrows heavily
from these disciplines. Standing on the
shoulders of giants, we now have a good idea of
how and why volcanoes work.
18
Modern Volcanology
Volcanoes mostly form at the boundaries of
tectonic plates
Arc volcanoes, more siliceous/explosive
Ridge volcanoes, basaltic
Hotspot volcanoes, basaltic
Subduction zone
Midocean ridge
Deep mantle source
19
Over 2500 volcanoes worldwide Over 650
historically active 160 in the North Pacific, gt
70 in Alaska alone
Modern Volcanology
20
Types of volcanoes Shields
Shields are made from many long thin lava flows,
tens of kilometers in diameter, have slopes of
about 10, and are typically of basaltic
composition.
At right, Mauna Loa in Hawaii
21
Types of volcanoes Shields
Kohala, Hualalai, Mauna Kea, Mauna Loa, Kilauea
Volcano, Hawaii
Olympus Mons, Mars
22
Types of volcanoes Calderas
Calderas often form at the summits of shields,
after catastrophic eruptions.
Okmok Volcano, Alaska
23
Types of volcanoes Calderas
Aniakkchak, Alaska
Veniaminof Alaska
24
Types of Landforms Cinder Cones
Cone A, Okmok Caldera
25
Types of Landforms Cinder Cones
Cinder cones are the most common volcanic
landform, often forming in late stages of
basaltic volcanoes.
Stromboli, Italy
SP Crater, Arizona
26
Types of volcanoes Stratocones
Stratocones are the full grown representation of
an active volcano. Often a stratocone precedes a
caldera.
Mt. Cleveland, Alaska
Pavlof Pavlof Sister, Alaska
27
Types of volcanoes Stratocones
Kliuchevskoi Group, Kamchatka
Shishaldin Volcano, Alaska
28
Volcano anatomy
Magma is created at depth and because it has a
lower density, it naturally rises to the surface.
This creates a series of pathways and storage
areas as the pressure and temperature have
effects on the physical properties of the magma.
29
Volcano anatomy
Since no one has ever visited the areas beneath a
volcano, many interpretations exist. There are
some physical constraints.
30
Volcano anatomy Magma Chambers
A word to chemical composition.
Volcanic rocks are characterized by their silica
(SiO2) content. They range in color from black
(low SiO2) to light brown (high SiO2). It is
important to remember that volcanoes can have
more than one type of magma, and even erupt it at
the same time. With time, basalt can become
rhyolite through elements being removed with
crystallization.
31
Basalt lt50 SiO2
Dacite to 62 SiO2
Andesite to 55 SiO2
Rhyolite gt65 SiO2
32
Magma Chambers We know that catastrophic
overturn prevails
33
Volcano anatomy Magma Chambers
34
Volcano anatomy Magma Chambers
35
Volcano anatomy Magma Chambers
36
Volcano anatomy Magma Chambers
37
Volcano anatomy Magma Chambers
38
Volcano anatomy Conduits
39
Volcano anatomy Conduits
Somehow the magma must get from the chamber to
the surface, it fractures rock and creates
conduits, most likely dikes
40
Volcano anatomy Conduits
41
Volcano anatomy Conduits
Flow can happen up and down in a dike.
42
Volcano anatomy Conduits
Magma Chambers -big open space models dont work
43
Types of activity Lava flows
Okmok Volcano, Alaska, AirSAR
Westdahl Volcano, Alaska SAR
Kilauea Volcano, Hawaii
44
Types of activity Lava flows
Westdahl Volcano, Alaska SAR
45
Types of activity Lava flows
Aa lava has a rough surface, and makes thick
flows (10s of meters). Pa Hoe Hoe flows smooth,
and make thin flows and series of pads. Lavas
are usually slow (cm / second)
46
Types of activity Lava flows
47
Types of activity Lava flows
48
Types of activity Lava Domes
Bezymianny Volcano, Kamchatka
Augustine Volcano, Alaska
49
Types of activity Lava dome collapse
When lava is too viscous or thick, it makes a
dome instead of a flow
Unzen Fugen-dake, Japan
Mt. St. Helens, Washington
50
(No Transcript)
51
Types of activity
52
Types of activity Hawaiian
53
Types of activity Strombolian
Located in the Tyrrhenian Sea north of Sicily,
EROS 1 image, January 2003.
54
Types of activity Strombolian explosions
Stromboli Volcano, Italy
55
Types of activity Strombolian explosions
Veniaminof, Alaska
56
Types of activity Strombolian
57
Types of activity Strombolian
The first use in Alaska for volcanoes was the
1999 Shishaldin eruption
Here an old analog FLIR operated by the State
Troopers was used to observe the eruption
58
Types of activity Plinian
Big explosions that may create pyroclastic flows.
59
(No Transcript)
60
Types of activity Pyroclastic flows
Mayon Volcano, Philippines
Mt. St. Helens, Washington
61
Types of activity Nuee Ardente (Glowing Clouds)
Tokachi-dake Volcano, Hokkaido Japan
62
Types of activity Ash plumes (and mudflows)
Etna, Sicily
Shishaldin Volcano, Alaska May 25, 1999 (Landsat
7)
63
Types of activity Things with water
Phreatomagmatic (meteoric water plus
magma) Vulcanian Surtseyan
64
Why do volcanoes erupt?

• More important for us today, why DONT they erupt?

Vulcano, Italy
65
WATER!
When suddenly heated, water changes to steam and
can explode. In the smallest cases it makes
bubbles and lets the magma rise to the surface to
erupt.
66
Types of activity Degassing
Kilauea, Hawaii
Vulcano, Italy
67
Types of activity Degassing
68
Types of activity Degassing
69
Types of activity Degassing

• Some facts on volcano degassing
• Volcanoes degas all the time
• Volcanoes have been present on planet earth for
  BILLIONS of years
• There are about 2500 active volcanoes
• About 1600 have erupted in historic time
• A volcanos lifespan is measured in millions of
  years

70
Types of activity Degassing

• Some facts on volcano degassing
• The primary volatile is water (80)
• About 15 is CO2
• About 5 is SO2
• We measure SO2 because it is easy, and related
  directly to magma, whereas water and CO2 can have
  meteoric sources.

71
Gas from 2500 volcanoes every day 1000 at 1
ton per day SO2 1kt SO2, 3 kt CO2, 7
kt H2O 750 at 10 tons per day SO2 7.5 kt
SO2, 22.5 kt CO2, 127.5 kt H2O 350 at 50
tons per day SO2 17.5 kt SO2, 52.5 kt CO2,
297.5 kt H2O 250 at 100 tons per day SO2 25
kt SO2, 75 kt CO2, 425 kt H2O 100 at 200 tons
per day SO2 20 kt SO2, 60 kt CO2, 340 kt
H2O 50 at 1 kt per day SO2 50 kt SO2, 150 kt
CO2, 850 kt H2O
This is 44 Mt SO2, 120 Mt CO2, 748 Mt H2O a
year Add eruptions, about 10 at any one time
adding gt1 kt per day SO2 Total in a year
volcanogenic gases adds up to around 0.5 Gt SO2,
1.5 Gt CO2, 5.4 Gt H2O
72
What causes volcanoes to erupt?
Internal forces, new magma, volatiles
73
What causes volcanoes to erupt?
External forces, interaction with ground water,
earthquakes
74
What causes volcanoes to erupt?
Environmental effects, rain, tides
75
What causes volcanoes to erupt?
Environmental forces, ice, erosion
76
How fast do volcanoes erupt?
SECONDS! At Mt. St. Helens, the ash clouds were
at supersonic speeds
77
How long do volcanoes remain active?
Millions of years, Toba caldera has known
eruptions over 5 million years ago, likely
longer. Okmok for many many thousands of years.
78
Volcano World http//volcano.und.edu/ Smithsonia
n Global Volcanism Program http//www.volcano.si.e
du/ Wohletz, Kenneth, and Grant
Heiken. Volcanology and Geothermal
Energy. Berkeley  University of California
Press,  1992. http//ark.cdlib.org/ark/13030/ft6v
19p151/