Volcanoes

Volcanoes

Constructive vs. Destructive

Volcanic eruptions are constructive in that they add new rock to existing land and form new islands.

Volcanic eruptions can be destructive when an eruption is explosive and changes the landscape of and around the volcano. 

Parts of a Volcano

Magma that reaches Earth's surface is known as lava.

Magma from the mantle rises to Earth’s surface and flows out an opening called a vent.

The vent as well as the mountain that forms around it from cooled lava, ash, cinders, and rock is called a volcano.

Ring of Fire

Most volcanoes occur along plate boundaries; an area in the Pacific Ocean where volcanoes are common is called the Ring of Fire.

Hot Spots

Hot spots do not occur at plate boundaries BUT instead in the middle of a tectonic plate.

H A W A I I

Hawaii formed over a HOT SPOT as the tectonic plate moves new crust moves over the hot spot, where a new Hawaiian volcano (or island) can form is this chain.

Multiple Choice

Which result from a volcanic eruption is considered constructive?

• add new rock to existing land and form new islands

• explosive and changes the landscape of and around the volcano

Multiple Choice

What is another name for magma that has reached Earth's surface?

• Vent

• Dust

• Ash

• Lava

Multiple Choice

Where is the Ring of Fire located?

• Indian Ocean

• Arctic Ocean

• Pacific Ocean

• Atlantic Ocean

Fill in the Blank

Hawaii is formed on a ___________.

Defining problems associated with volcanoes: 

Most of the world’s active above-sea volcanoes are located near convergent plate boundaries, an area of subduction. Subduction-zone volcanoes typically erupt with an extremely explosive force. There are many large population centers that are within areas that may be affected by explosive volcanic eruptions.

 Local effects

Personal property damage, personal injuries or possible death, destruction of urban and suburban areas, disruption of local water supplies, contamination of food sources, acid rain, landslides, and lack of breathable air.

The 1980 eruption of Mount St. Helens and after effects illustrate the local hazards.

Global Effects

Changes in weather and climate, aviation safety hazards, tsunamis if volcanic activity is under or near oceans, seismic activity in accompaniment with volcanic activity, and production of acid rain

Multiple Select

Check all that would be considered local effects of a volcanic eruption.

• lack of breathable air

• acid rain

• contamination of food sources

• destruction of urban and suburban areas

• Disruption of water supply

Multiple Select

Check all that would be considered global effects of a volcanic eruption.

• changes in weather and climate

• aviation safety hazards

• possible death

• seismic activity

• personla injury

Minimization Efforts of Volcanic Effects: 

Predicting exactly when an eruption occurs is difficult, but scientists can observe the effects of past eruptions by studying landforms and geologic deposits. 

Monitoring seismic activity, gas chemistry, and land deformation can help scientists warn that an eruption might occur soon. This provides enough warning for people in the potentially affected areas to be evacuated. 

Scientists suggest the following for structures where volcanic activity may occur: 

- Houses should be constructed in a manner that will allow for all vents to be closed. 

- Windows and doors should be properly insulated.

Multiple Select

What are ways for scientist to predict volcanic activity and give people time to evacuate?

• studying landforms and geologic deposits

• monitoring seismic activity

• land deformation

• scuba diving

Poll

Would you want to live near a volcano?

• Yes

• No