5.3

Volcanoes affect Earth’s Volcanoes affect Earth’s land, air, and waterland, air, and water

Pages 156-162 (section B)Pages 156-162 (section B)

Immediate Effect of Volcanic Immediate Effect of Volcanic EruptionsEruptions

• Lava Flows– Most lava flows move slowly enough that

people can move away and not be hurt.– Lava flow can knock down, cover, or burn

nearly everything in its path


• Volcanic Ash– Volcanic ash is heavy because it is made up tiny

pieces of rock– The weight of volcanic ash can cause the roofs to

collapse– Volcanic ash can clog machinery, including cars

and airplanes– Can suffocate animals and people


• Mudflows– Landslides that occur when loose rocks and

soil and rocks are mixed with water– Heat from an eruption can melt any ice and

snow very quickly– Also form as ash mixes into rivers– Fast flowing mudflows have buried entire

towns


• Pyroclastic flows– Tend to rush downhill, following valleys, BUT can

have enough force to climb up hills– Can leave a thick layer of volcanic rock fragments

as it passes through an area– The most dangerous type of eruptions: in 1902

almost 30,000 people were killed within a few minutes


• Landslides– Part of a volcano can collapse and start a landslide– A landslide can cause a tsunami if a large amount

of material falls into the ocean


• Steam explosions – Relatively uncommon, but can be devastating– They occur when magma comes near water

or into contact with it.– A steam explosion may have caused the

destruction of Krakatau, in 1883

Long-term Destructive Effects of Long-term Destructive Effects of Volcanic EruptionsVolcanic Eruptions

• Mudflows can continue to develop over time when rain mixes with the rock fragments thrown out

• Water can fill in the crater of the volcano. The upper part of the crater is weak and easily collapse

• When the lava cools, it forms a layer of hard rock

Long-term Positive Effects of Long-term Positive Effects of Volcanic EruptionsVolcanic Eruptions

• After many years, the hardened lava can break down and it creates rich soil

• Highly productive farmland surrounds some active volcanoes

• Over time, repeated volcanic eruptions can build a magnificent landscape of mountains and valleys.

• People chose to live in these areas for the natural beauty, many tourist visit for the areas as well.

Volcanic Gases and Ash affect the Volcanic Gases and Ash affect the AirAir

• Sulfur dioxide, which smells like rotten eggs, is a gas common in volcanic eruptions

• Carbon dioxide, which is odorless and colorless, can be fatal to humans

• Gases from the volcano can help to carry ash 100’s of miles

Acid RainAcid Rain

• Acid Rain- rain that contains large amounts of acid

• Volcanic eruptions are a source of acid rain– Human activity is

the most common source of acid rain

Volcanic Activity affects WaterVolcanic Activity affects Water

• Hot springs form as magma heats water

• In most hot spring, the water flows out in calm pool

• Geyser- a type of hot spring that shoots water into the air.


• Fumarole- similar to a hot spring, instead of water a fumerole releases steam and other gases


• Deep- Sea Vent- hot spring that form at spreading centers in the ocean.