Volcanoes Tungerahua Volcano, Ecuador Picture by Alcinoe Calahorrano Talk about this volcano when it erupted and what it is doing right now. Tungerahua Volcano, Ecuador Picture by Alcinoe Calahorrano Volcanoes

Volcanoes form around vents that release magma onto the Earth’s surface. Lava Magma chamber

Nonexplosive Eruptions Volcanic Eruptions Lava flow Lava fountain Nonexplosive Eruptions Explosive Eruptions What is Lava? -magma that flows onto the Earth’s surface

The Composition of Magma Determines whether it is explosive or not! water High water content More likely to be !!! High content More likely to be !!! Why? Silica has a thick, stiff consistency Flows slowly Tends to Harden in the volcano’s vent EXPLOSIVE silica EXPLOSIVE The Earth is made of many different and distinct layers. The deeper layers are composed of heavier materials; they are hotter, denser and under much greater pressure than the outer layers. Core: The Earth has a iron-nickel core that is about 2,100 miles in radius. The inner core may have a temperature up to about 13,000°F (7,200°C = 7,500 K), which is hotter than the surface of the Sun. The inner core (which has a radius of about 750 miles (1,228 km) is solid. The outer core is in a liquid state and is about 1,400 miles (2,260 km) thick.

What Erupts from a Volcano? Blocky lava Lava can be thick or thin. Pahoehoe Aa Pillow lava

What Erupts from a Volcano? Pyroclastic material Rock fragments created by eruptions magma explodes from volcano and solidifies in the air existing rock is shattered by powerful eruptions EXPLOSIVE Lapilli Volcanic bombs Volcanic blocks Volcanic ash

How do volcanoes affect the Earth? Flows and Fallouts hot ash can flow really quickly Knock down buildings Dam rivers (flooding/drought) Kill crops and livestock Climatic Changes Ash & Gases can block sunlight Drop average global temperature noticeably

Types of Volcanoes Shield volcano Cinder cone volcano Composite volcano

Craters, Calderas, and Lava Plateau From explosions of material out of the vent and the collapse of material back into vent Caldera Much larger depression that forms when magma chamber empties and its roof collapses Lava Plateau Forms when lava erupts from long cracks, or fissures, and spreads out evenly (thousands of km)

What causes volcanoes? The Formation of Magma Mantle rock melts when the temperature increases or the pressure decreases. There are lots of uncertainties about why volcanoes form, because scientists have to rely on models based on rock samples and other data.

What causes volcanoes? Where Volcanoes Form Tectonic Plate Boundaries!!! There are lots of uncertainties about why volcanoes form, because scientists have to rely on models based on rock samples and other data. ~75% world’s active volcanoes in Ring of Fire

What causes volcanoes?

What causes volcanoes? Hot Spots

How do volcanologists predict eruptions? Measuring Small Quakes Before eruption, increase in number & intensity Measuring Slope Bulges may form with magma (tiltmeter) Measuring Volcanic Gases Outflow of volcanic gases Sulfur dioxide, carbon dioxide Measuring Temperature from Orbit Measure changes in temperature over time

You should not be a Volcanologist if…. You don’t like hiking, backbacking, rockclimbing, etc. You are not interested in experiencing extreme temperatures and heights. If you don’t like to travel to incredible places and see breathtaking views of the world. Robert McGimsey USGS A. Ozerov