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More Fun with plates THE END IS NEAR! Volcano! A little review The Surface of the Earth is made up of very large plates that are moving Is there really magma just below the crust all around the world? No… Pockets of magma form and… Push, rise upward, less dense than surrounding rock… Most forms at plate boundaries… Plate Boundaries!! Convergent, divergent, transform fault – but volcanoes only occur at certain locations… 1 subduction (convergent) 2 mid ocean ridges (divergent) 3 hot spots Remember this map? Map of where earthquakes and volcanoes occur A volcano can be…. An active volcano is one that has erupted recently or volcanologists see the possibility of an eruption soon. A dormant or sleeping volcano is a volcano that has been quiet for a long time, but still has signs it may erupt again. An extinct volcano is one that has not erupted for thousands of years. Sometimes it is hard to tell if a volcano is dormant or extinct. Volcanic eruptions can be….. Explosive – Mt. St Helens Quiet Kilauea What is released from volcanoes? Lava Various gasses Steam Pyroclastic materials (tephra) – Volcanic ash – Volcanic dust – Lapilli – Pyroclastic bombs and blocks What are the different types of lava? Mafic – flows easily – Oceanic crust – Dark when hardened – pahoehoe, – Aa – Pillow lava Felsic – Continental crust – Light when hardened Types of Lava Felsic, thicker flowing lava shows the following behaviors: – It tends to flow slowly, clog, and form semi-solid blocks which resist flow – It tends to entrap gasses, which form bubbles within the rock as they rise to the surface – explosive eruptions and is associated with pyroclastic flows Lava with low viscosity, flows easily shows the following behaviors: – It tends to flow easily, forming puddles, channels, and rivers of molten rock – It tends to easily release bubbling gases as they are formed – Eruptions are rarely pyroclastic and are usually quiet Types of Lava There are three forms of lowviscosity lava flows: aā, pāhoehoe, and pillow lava. They are described in relation to basaltic flows from Hawaii pāhoehoe Pāhoehoe - Rope – Looks like rope Aa (AH! AH!) A`a (pronounced "ah-ah") is a Hawaiian term for lava flows that have a rough rubbly surface composed of broken lava blocks called clinkers. Because the way the lava moves and the clinkers, the lava leaves sharp and jagged remains… this is where the name came from. Pillow Lava Forms underwater Rapid cooling makes it look like a pillow. What are the different types of volcanoes? Shield Cinder cone Composite or stratovolcano Caldera Lava dome Shield Volcano a broad, shallow volcanic cone mafic lava flows and cools slowly Kilauea, Hawaii is an example Cinder cone volcano throws much ash into the air built up from alternate layers of ash and cinder. Little or no lava emitted Paricutin, Mexico is one example Composite Layers of lava and pyroclastic materials Often develop into high volcanic mountains create many vents that leave through the smaller craters Ex: Mt St Helens – Merapi, Indonesia Caldera An older volcano with a large crater which can be 62 miles(100km) wide. In this crater many little new craters are formed. VERY dangerous. Larger Caldera’s can be very hard to notice at first. Signs of Calderas include hot springs, or geysers Dome Volcano This one has a steep, convex slope from thick, fast-cooling lava Hint: It’s shaped like a dome Researching your volcano… 1 powerpoint slide with the following… – All the info required in the table – Date of most famous eruption – Date of most recent eruption/activity – Photo/picture – Map showing location – 2nd slide: bibliography Fill in the table for your volcano Name of volcano Location Active, extinct, Eruption: dormant? Quiet or explosive? What was/is emitted? Type of volcano Damage Volcanoes Eyjafjallajökull, Iceland Merapi, Indonesia Kilauea, Hawaii Mount St. Helens, Washington Vesuvius, Italy Pinatubo, Philippines Paricutin, Mexico Pelee, Caribbean Krakatau, Indonesia Etna, Italy Katmai, Alaska Santa Maria, Guatemala Santorini, Greece Your ppts here!!! Largest eruptions ever… Can you name 3 of the top 20? http://volcano.oregonstate.edu/book/export/ html/227 Deadliest eruptions? http://volcano.oregonstate.edu/deadliesteruption Are there volcanoes in the US? Of course in – Alaska – Hawaii – Also – Western US! Current Caldera Is the Yellow Stone Caldera Growing? – We don’t know – We are currently studying the caldera Parts of a Volcano Dike – Magma/Lava that pushes out of the main vent in a new direction. This does not go along the bedding from older layers Sill – Magma that moves along the layers of previous eruptions Vent – Main place lava escapes from Crater – opening in the volcano Magma Chamber- where gathering Magma builds up pressure for the coming eruption I would hate to have this guy’s House I think they mean it!!!! Some people ARE crazy What types of damage? How can humans and animals die? Hit by pyroclastic flow Breathe in poisonous gasses Mud and ash slides, lahars when rains wash down the accumulated ash Heat What info, data can scientists use to predict eruptions? Historical data Monitor air quality, – Gasses that might be emitted Check local geology Soil temperature? Seismic activity Bulging ground on, near volcano Can volcanoes affect climate, weather? gasses and ash more clouds form More of sun’s energy is reflected back to outer space Less energy makes it to earth’s surface Global cooling! Ex: Krakatoa eruption, crop failures OR Some volcanoes can release massive amounts of Carbon Dioxide, methane and other gasses. These gasses can trap heat within the atmosphere, And increase the temperature of the planet.