Unit 2 : Inside Earth Volcanoes!!!

Which releases more energy? Atomic bomb volcano

If you voted for the volcano you are right! A volcanic explosion is 10,000 times stronger than the force of the first atomic bomb. The force can kill people, plants and animals Poisonous gases can kill if breathed in by people and animals Tsunamis, floods, rock falls, mudflows can be triggered Volcanic ash can stall out jet engines Lava flows can start fires, kill people, and bury towns http://video.nationalgeographic.com/video/player/environment/environment-natural-disasters/volcanoes/volcano-eruptions.html

1980-2008 Volcano Stats Number of events: 140 Number of people killed: 25,197 Average people killed per year: 869 No of people affected: 4,080,791 Average people affected per year: 140,717 Economic Damage (US$ X 1,000): 2,870,769 Economic Damage per year (US$ X 1,000): 98,992

What are volcanoes? Volcanoes are areas of the Earth’s surface through which magma and volcanic gases pass. Most volcanoes are found along the Ring of Fire , an area that circles the Pacific Ocean

Two Kinds of Eruptions Most common type Non-explosive Explosive Most common type Produce huge amounts of relatively calm lava Found on much of the seafloor and Northwestern US Much rarer than non-explosive. Incredibly destructive!!! Clouds of hot debris, ash and gas rapidly shoot out of the volcano Volcanic ash produced by explosive volcanoes can get stuck in the atmosphere and circle the Earth for years In a matter of seconds, an explosive volcano can demolish an entire mountainside

Two Kinds of Eruptions Non-Explosive Explosive

What is inside a volcano? If you could look inside a volcano, you would see the features on the graphic. Magma chamber: a body of molten rock deep underground that feeds the volcano Vents: cracks in the Earth’s surface though which magma is released during an eruption

What erupts from a volcano? Magma erupts as either lava or pyroclastic material Lava is the liquid magma that flows from a vent http://www.youtube.com/watch?v=K9iZd6wzlCk&feature=related&safety_mode=true&persist_safety_mode=1 Pyroclastic material forms when magma is blasted into the air.

Four Types of Lava Aa lava Low viscosity Pours out quickly Forms a brittle crust The crust is torn into jagged pieces as molten lava continues to flow underneath Named by the first person to try to walk on it!

Four Types of Lava Pahoehoe High viscosity Flows slowly – like wax dripping from a candle Glassy, wrinkled surface

Four Types of Lava Pillow Lava Low viscosity Quick flowing Underwater eruptions Forms rounded lumps that are in the shape of pillows

Four Types of Lava Blocky Lava High viscosity Flows slowly Oozes from a volcano and forms jumbled heaps of sharp edged chunks Does not travel far from the erupting vent

Four Types of Pyroclastic Material Volcanic Bombs: large blobs of magma that harden in the air. Lapilli: pebble-like bits of magma that hardened before they hit the ground. Means “little stones” in Italian Volcanic ash: forms when gases in magma explode. Most pyroclastic material is ash Volcanic blocks: pieces of solid rock erupted from a volcano. Larges pieces.

Pyroclastic Materials

Pyroclastic Flows One particularly dangerous type of volcanic flow is called a pyroclastic flow. Enormous amounts of hot ash, dust, and gases are ejected from a volcano. Travel at speeds faster than hurricane-strength winds! http://www.youtube.com/watch?v=yvG_N7eqMWk&safety_mode=true&persist_safety_mode=1

The Effects of Volcanic Eruptions In 1816, a man in Connecticut laid his clothes out to dry overnight. When he woke up, they were frozen solid. This would not be weird if it wasn’t June 10!! What happened?? A volcanic island on the other side of the world had sent a cloud of volcanic ash into the atmosphere and cause the “Year Without A Summer” http://www.youtube.com/watch?v=5SuaukufKsI&safety_mode=true&persist_safety_mode=1 Volcanic ash and gasses can block sunlight and cause global temperatures to drop!

Different Types of Volcanoes While volcanic eruptions can cause major changes to the Earth’s climate, the changes to the Earth’s surface are more familiar. There are three basic types of volcanoes Shield Cinder Cone Composite

Shield Volcanoes Built of layers of lava released from repeated non-explosive volcanoes. Gently sloping sides Can be enormous Mauna Kea in Hawaii

Cinder Cone Volcanoes Made of pyroclastic material produced from moderately explosive volcanoes. Steep slopes Small and usually erupt for a short period of time. Occur in clusters Quick erosion http://videos.howstuffworks.com/discovery/29457-assignment-discovery-paricutin-video.htm Paricutin in Mexico

Composite Volcanoes Most common type Form from explosive eruptions of pyroclastic material followed by flows of lava. Broad bases and steep sides Mt. Fuji in Japan, Mt. St. Helens in US

Other types of volcanic landforms Craters: funnel shaped pit a the top of the central vent of a volcano. Caldera: a large, semi-circular depression that forms when the magma chamber partially empties and the roof collapses.

Causes of Volcanic Eruptions Magma forms in the deeper regions of the Earth’s crust and in the uppermost layers of the mantle. Magma is a very hot, plastic rock that flows slowly.

How do volcanoes form Usually the pressure from the rock above keeps the magma’s atoms so tightly compressed that the rock cannot melt. When this pressure is released, such as at the boundary of tectonic plates, the magma slowly rises to the surface

Where do volcanoes form? Tectonic plate boundaries Divergent boundaries --- plates move apart 15% of volcanoes Mid-Ocean ridges Convergent boundaries --- plates collide 80% of volcanoes Subduction Hot Spots A volcanically active area far from tectonic plate boundaries 5% of volcanoes Hawaii http://www.youtube.com/watch?v=jRfEGvp6wDU

Divergent Boundary Volcano

Convergent Boundary Volcano

Hot Spots!