Volcanoes

Volcano facts How many

eruptions? 15,110 volcanoes in

last 10,000 years The highest peak?

6,887 m, Ojos del Salado (Chile)

The biggest eruption?

2,500 km3, Yellowstone, 2.2 Ma (USA)

First volcanologist?

79 AD - Pliny the Younger

Total deaths 238,000 (1600-1982)

History The word Volcano is derived from the name of

the ancient Roman island of Vulcano. The Romans believed that Vulcan, the god of Fire and the maker of weapons, used the volcano on that island to forge his weapons.

Definition of a Volcano 1. An opening in the crust of the Earth from

which magma and gases escape to the surface.

2. The mountain that is formed from volcanic processes.

Volcano Classification Active- are either currently erupting or have

erupted recently. Over 500 volcanoes are in this group.

Dormant- are not currently erupting but are considered likely to do so. Mt. St Helens was dormant for 123 years before it erupted in 1980.

Extinct- or dead volcanoes have not erupted in recent history and are not likely to erupt.

Anatomy of a Volcano

A volcano is a mountain formed of lava and/or pyroclastic material.

A crater is the depression at the summit of a volcano or that which is produced by a meteorite impact.

A conduit, or pipe, carries gas-rich magma to the surface.

Anatomy of a Volcano

Types of Volcanoes

The three main volcanic types are shield volcanoes, cinder cones composite cones

Shield Volcanoes

Shield volcanoes are broad, gently sloping volcanoes built from fluid basaltic lavas.

Cinder Cones

Cinder cones are small volcanoes built primarily of pyroclastic material ejected from a single vent. Steep slope Small is size Occur in groups

Cinder Cones

Composite Cones

Composite cones are volcanoes composed of both lava flows and pyroclastic material. Most are located in the Ring of Fire

(Ex Mt. Rainer) Large in Size Most Violent Eruptions

Composite Cones

Mt. Rainer

Mount St. Helens Before and After the May 18, 1980, Eruption

Composition of the Magma Temperature of the Magma Dissolved Gasses

Viscosity- is the measure of a material's resistance to flow. Temperature- hotter magma’s are less viscous Composition- Silica Content

High Silica- high viscosity Low Silica – low viscosity

Factors Affecting Eruptions

There Are Three Major Volcanic Zones

Subduction ZonesMid-oceanic ridgesHot spots

There are Two Different Types of Lava

Pahoehoe lava (resembles braids in ropes) Aa lava (rough, jagged blocks)

Pyroclastic materials is the name given to particles produced in volcanic eruptions

Pahoehoe (Ropy) Lava Flow Fast Moving

Slow-Moving Aa Flow

Mt. Saint Helens Erupting

  Mount Saint Helens photographs 10-26-041980 Eruption

http://www.youtube.com/watch?v=njV9ski1gB4

http://www.youtube.com/watch?v=pGImksoOwtU&feature=related

http://www.youtube.com/watch?v=1Vn6kxfD3Ek&feature=related

Pompeii- Italy

Santorini Greece

Old Faithful- Yellowstone

Sunset Crater – Flagstaff Arizona

Mt. Merapi Nov 1, 2010

Eyjafjallajokull- Iceland

Kilauea Hawaii- Most active volcano

Popocateptl- Mexico

Mt Erebus Volcano- Antarctica One of the worlds

most active volcanoes