VolcanoesDay 1

October 6, 2010

Objectives

• I will be able to identify what makes _______ _____________________________________

• I will be able to compare _______ _______ that come out of a volcano.

• I will be able to compare the different _______ _______ _______ _______ _______

Key Points• A magma’s viscosity is directly related to its silica content.• A lava flow with a surface of rough, jagged blocks and sharp,

angular projections is called aa flow.• As the temperature of lava increases, the viscocity decreases.• Highly explosive volcanoes tend to have magma with high silica,

high viscosity, and higher gas content.• The particles produced in volcanic eruptions are called

pyroclastic material.• Pyroclastic materials include ash, cinders and lapili.• The most abundant gas associated with volcanic activity is

water vapor.• A cinder cone is a type of volcano that is built almost entirely

from ejected lava fragments.• The pipe is the hollow center of the volcano.

Factors Affecting Eruption

• Volcanoes can erupt _______ _______ or _____ _______ __. They can erupt with lots of lava spewing out or slowly oozing out of the mouth. Some volcanoes erupt ash and dust with no lava at all. So what makes all of them so unique?

• Let's watch!• Let’s take a look at the factors that affect the

eruption of a volcano.

Factors Affecting EruptionViscocity - _______ _______ _______ _______

_______ _______ _______ _______ ______. – This means that something that has a high

viscosity does not flow easily. A substance with a high viscosity would be honey. A substance with a low viscosity would be water.

– If the lava of a volcano has _______ _______, the _______ of a volcano will be _______ _______.

– There are three factors that affect the viscocity of lava: ___ _______ ____ _______, _______ content, and _______.

Factors Affecting Eruption1. Silica – the more silica in lava, the more _______

it has. A magma’s viscosity is directly related to its silica content.

2. Gas content - the more _______ in lava, the _______ viscocity it has.

3. Temperature – as temperature in lava increases, _______ _______ _______ _______ _______. • Example: heating up syrup.

***Bottom line: _______ _______ _______ volcanoes tend to have magma with high _ _______ ______,

_______ _______ viscosity, and higher _______ content.

Volcanic MaterialThere are three main types of materials that come out of volcanoes: ___ _______ ____, _______, and _______ _______ _______.Lava flows: 1.aa flow (AH ah): A lava flow with a surface of _______, jagged _______ and sharp, angular _______. view here! Think “ow!” it hurts to step on!•pahoehoe flow: lava flows that flow _______ forming flows that look like twisted braids in ropes.

view here!Gases:The most abundant gas associated with volcanic activity is _______ _______.

Volcanic Material

Pyroclastic Material – _______ _______ _______ _______ _______ _______ _______ _______ _______ _______ _______ _______

• Pyroclastic materials include _______, ___ _______ _______ ____ and _______.

• These particles can range in _______ from fine dust to pieces that weigh several tons!

Types of VolcanoesAnatomy of a volcano• While there are several different types of

volcanoes, each have a “typical” anatomy with the following parts:

A. _______B. _______C. _______D._______

Types of Volcanoes

• The three main types of volcanoes are _______ cones, _______ volcanoes and _______ _______ cones.

• _______ _______ _______ plays a major part in determining the _______ of a volcano.

Types of Volcanoes

• When you think about a typical volcano, what do you see?

• Usually a cinder cone – highly explosive lava.1.A cinder cone is a type of volcano that is built

almost entirely from _______ _______ _______ _______ _______.– This give it a cone shape over time.– Learn more here!

Cinder Cone Volcano

Cinder Cone from Pu'u'O'o eruption of Mount Kilauea

Types of Volcanoes

2. Composite Cones – a _______, symmetrical volcano composed of both _______ and _______ _______ deposits.

About Composite Cone Volcanoes

Composite Volcano

Mt. Shasta

Types of Volcanoes

3. Shield Volcano – have the shape of a broad, slightly _______ structure.

• Most shield volcanoes grow up from the _______ _______ – like the islands of Hawaii or Iceland.

More about shield volcanoes

Shield Volcano

Iceland