Lava CompositionWhich element is found most in lava? • Lava is about 50%

Silicon. • Silicon makes lava thick

(high viscosity).• The more silicon you

have in lava the more explosive the eruptions will be in a volcano.

• What is building up?• Gas and pressure build

up under the thick lava.

Silicon!

Lava Behavior

• The viscosity of lava is important because it determines how the lava will behave.

• Lavas with high viscosity are rhyolite, dacite, andesite and trachyte, with cooled basaltic lava also quite viscous.

Rhyolite

Andesite

Dacite Basalt

Trachyte

Lava Behavior

• Lavas with low viscosities are freshly erupted basalt, carbonatite and occasionally andesite.

Basalt

Carbonatite

Andesite

Highly viscous lava behaviors:

• Tends to flow slowly, clog, and form semi-solid blocks which resist flow

• Tends to entrap gas, which form vesicles (bubbles) within the rock as they rise to the surface

• Explosive eruptions and is associated with tuff and pyroclastic flows

• Highly viscous lavas do not usually flow as liquid, and usually form explosive fragmental ash or tephra deposits.

Low viscosity lava behaviors:

• Tends to flow easily, forming puddles, channels, and rivers of molten rock

• Tends to easily release bubbling gases as they are formed

• Eruptions are rarely pyroclastic and are usually quiet

• Volcanoes tend to form broad shields rather than steep cones

Why you should never park too close!

Home Sweet Home

Lava at Night!

The Royal Gardens

Lava Side Hotel

Lava Side Hotel

Lava Side Hotel

Lava Side Hotel Roof

Rain Water Catchment Tanks

Lava Side Hotel Backyard

Lava Fountains

Lava Flows

Volcanologist

Volcanology

Volcanology

Volcanology

Volcanic ash• Volcanic ash- small

sharp glass-particles that damage anything they come across.

• Volcanic ash exploded from a vent in fragments less than 2mm in size. 

• Dangerous because… • Can cause houses and

buildings to collapse.• People and animals may

die from lack of oxygen.

An eruption from Cleveland Volcano,

Chuginadak Island, Alaska,

Volcanic gas• Volcanic gas is gases

contained within magma.

• * Water Vapor is the gas that is released the most

• Other gases include carbon dioxide (CO2), sulfur dioxide (SO2), and hydrogen sulfide (H2S).

• Dangerous because…• These gases can kill

people and animals and cause acid rain and contribute to greenhouse effects.

Volcanoes are the largest natural polluters!

Steam Vents

Steam Vents

Global Impact• When a volcano erupts

it throws out a lot of ash.  At short notice this ash can be very harmful to the environment by killing plants and animals.

• However, over a long period of time, the ash layer contains many useful minerals, that are converted into fertile soil.

• Volcanoes provide resources for energy extraction, also called geothermal energy. 

• Heat from the earth's crust is being converted to energy.  Advantages to this type of energy are that it is very clean and the resources are nearly inexhaustible.

Volcanic ash makes for good

fertile soil for plants and trees

as it breaks down over

time.

Technology in Science• Using infrared,

scientists were able to identify specific warning signs before the eruption of the nearby Bezymianny volcano (Russia) in December 2006.

• Flowing lava shows up as bright yellow in an infrared image (top) of Russia's Klyuchevskoy volcano.

Positives and Negatives of

Volcanoes Positives• Lava flows create

extremely fertile soil for crops and plants.

• Creates new beautiful land (over long periods of time)

• Emits water vapor• Create Geothermal

energy• Help us understand past

civilizations (Pompeii) and cultures and even the Earth itself!

Negatives• Getting caught in volcanic

dangers (blasts, lava flows, pyroclastic flows, lahars, and ash clouds) can be deadly.

• Destroys anything in their path.

• Puts out large amounts of carbon dioxide (greenhouse

gas) and sulfur dioxide. • SO2 is a cooling gas that can

drop global temperatures after a large eruption.

• SO2 also causes acid rain

Infamous moments in volcanic history

• The eruption of Mount Vesuvius in Italy, in 79A.D., spewed ashes and lava fragments that buried the city of Pompeii and caused a mudflow that destroyed the nearby city of Herculaneum.

• The 1883 eruption of Krakatoa in Indonesia, considered one of the most catastrophic in history, set off explosions that could be heard almost three thousand miles away; spewed gases and vapors that rose to a height of seventeen miles (twenty seven kilometers); and let loose a tsunami that killed thirty six thousand people on nearby islands.

Infamous moments in volcanic history

• The year 1816 often has been referred to as "the year without a summer". It was a time of significant weather-related disruptions in New England and in Western Europe with killing summer frosts in the United States and Canada. These strange phenomena were attributed to a major eruption of the Tambora volcano in 1815 in Indonesia. The volcano threw sulfur dioxide gas into the stratosphere, and the aerosol layer that formed led to brilliant sunsets seen around the world for several years.

Infamous moments in volcanic history

• In June 1991, the second largest volcanic eruption of the twentieth century* took place on the island of Luzon in the Philippines, a mere 90 kilometers (55 miles) northwest of the capital city Manila. Up to 800 people were killed and 100,000 became homeless following the Mount Pinatubo eruption, which lasted for nine hours of eruptions on June 15, 1991. On June 15, millions of tons of sulfur dioxide were discharged into the atmosphere, resulting in a decrease in the temperature worldwide over the next few years.

Infamous moments in volcanic history

• The cloud over the earth reduced global temperatures. In 1992 and 1993, the average temperature in the Northern Hemisphere was reduced 0.5 to 0.6°C and the entire planet was cooled 0.4 to 0.5°C. The maximum reduction in global temperature occurred in August 1992 with a reduction of 0.73°C. The eruption is believed to have influenced such events as 1993 floods along the Mississippi river and the drought in the Sahel region of Africa. The United States experienced its third coldest and third wettest summer in 77 years during 1992.

Earth Exam Focus

• Know the structure of the volcano.• Know the different types of volcanoes.• Know where volcanoes form and why.• Know the dangers associated with

volcanoes.• Know what lava is made up of.• Know what makes some volcanoes

more explosive than others.