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Earth Science 3.3
| Question | Answer |
|---|---|
| Hot spot | - A place on the earth’s surface that is directly above a column of rising magma |
| volcano | A vent in the earth’s crust through which magma, steam, ashes, and gases are forced. |
| rift | A deep crack that forms between two tectonic plates as they separate |
| Subduction zone | A place where one tectonic plate is pushed under another tectonic plate |
| Aa | Lava that has a rough surface |
| Pahoehoe - | Lava that has a smooth or billowy surface |
| Pluton - | A body of magma that has hardened underground |
| Pyroclast - | A solid volcanic material such as ash and rock that has been ejected during an eruption |
| Volcanic bomb - | A fragment of molten rock that is shot into the air by a volcano |
| Caldera - | A volcanic crater that is greater than 2 km in diameter and is formed by the collapse of surface rock into an empty magma chamber |
| Plug - | A structure of hardened magma that forms inside a vent |
| Tiltmeter - | An instrument that uses liquid to register changes in the earth. |
| Name three ways a volcano can form. | A volcano can form over a hot spot. Volcanoes can form in subduction zones at plate boundaries. Volcanoes can form at divergent boundaries. |
| How do volcanoes help scientists study the interior of the earth? | Give scientists direct evidence of what is inside the earth. |
| How do volcanoes grow? | Intrusion - magma moves up inside the volcano and stays there Extrusion - erupts and lava comes out |
| What important roles do volcanoes play in creation? | Make the soil fertile Allow the earth to vent pressure inside the earth |
| Where do most volcanoes occur? | Most volcanoes occur on plate boundaries because that is where magma can escape. |
| How are volcanoes formed along the Mid-Atlantic Ridge? | Along divergent boundaries - as the plates separate, magma from the mantle can come up through the rifts between the plates. |
| How are volcanoes formed along a subduction zone? | As the oceanic plates subduct under the continental plates, the collision causes rock to melt and gases to be released. The gases and melted rock then find their way to the surface. |
| Why are volcanoes along a subduction zone more violent than volcanoes on the Mid-Atlantic Ridge? | The heat generated by collisions in subduction zones melts the mantle, which increases the pressure on the magma. |
| Why are the volcanoes formed from oceanic-oceanic plate collisions the most violent? | The magma in these volcanoes contains dissolved water and carbon dioxide. The gases are released in very explosive, lava-spewing eruptions. |
| What is the difference between pahoehoe lava and aa lava? | Aa lava has a rough surface Pahoehoe lava has a smooth or billowy surface |
| What is a pluton? | An intrusive body of magma that has cooled and hardened underground. |
| Why are crystals larger in plutonic rock than in other volcanic materials like pyroclasts? | Plutonic rock is intrusive, so it cools and hardens underground. It takes longer to cool than pyroclasts, which cool aboveground. Because plutonic rock cools more slowly, its crystals have more time to grow. |
| What are three categories of volcanoes and how are these determined? | Active - have erupted recently or will erupt soon Dormant - have no recent history of eruptions and show no signs of erupting Extinct - can no longer erupt |
| What is a shield volcano? | Shield volcano has a gentle slope and is spread out over a large area. It is made mostly of lava flows. |
| What are the two types of eruptions that can form shield volcanoes? | Shield volcanoes can be formed by Icelandic or Hawaiian eruptions. These eruptions contain little to almost no gas and the lava is thin. Icelandic eruptions are mild and Hawaiian eruptions are mild to moderate in nature. |
| Compare a cinder cone to a composite volcano. | Cinder cone - small, cone-shaped volcano made of ash and cinders, one vent, rarely more than 300 m high Composite volcano - much larger and steeper than cinder cone, alternating layers of pyroclastic materials and lava, sides reinforced with many dikes |
| List the eruptions in order from least violent to most violent. | Icelandic, Hawaiian, Strombolian, Vulcanian, Pelean, Plinian |
| What are the components of an eruption? | Heat, pressure, gases, lava, and pyroclastic materials. |
| Give three examples of eruptions and how their components affect the eruption. | Icelandic - very little gaseous content, thin lava, several vents Hawaiian - mild to moderate eruption of gases, thin lava, one vent or several fissures Strombolian - runny lava, steam or gases, pyroclasts, volcanic bombs, single vent |
| Give three examples of eruptions and how their components affect the eruption. (2) | Vulcanian - dark ash, thick lava, steam, gases Pelean - fine ash, thin lava, gases, pyroclastic material, superheated steam Plinian - hot ash clouds, pyroclastic flows, thick magma, abundant gases |
| What changes do volcanologists monitor? | Change in gases Change in temperature of the volcano and nearby streams Change in the ground size and shape |
| What causes a volcano to bulge? | Rising magma can cause a volcano to bulge |
| What geologic event can precede a volcanic eruption? | Earthquake |
| What problems can be caused by heavy volcanic ash? | Can block out the sun, collapse roofs, causing breathing problems for humans and animals, smother crops, pollute rivers, and destroy buildings |
| What other problems can be caused by volcanic eruptions? | Pyroclastic flow can tear down trees and destroy buildings |
| What benefits come from volcanic eruptions? | Fertile soil Provides building materials Can be used in hand soap and cleaners Diamonds are brought to the surface Release trapped gases |
Created by:
basflowers