Volcanoes March 9, 2011 Objectives I will be able to identify what makes ________ _____________________________________ _ I will be able to compare _________________ that come out of a volcano. I will be able to compare the different _____________________________________ _ Key Points A magmas viscosity is directly related to its silica content. A lava flow with a surface of rough, jagged blocks and sharp, angular projections is called aa flow. As the temperature of lava increases, the viscocity decreases. Highly explosive volcanoes tend to have magma with high silica, high viscosity, and higher gas content. The particles produced in volcanic eruptions are called pyroclastic material. Pyroclastic materials include ash, cinders and lapili. The most abundant gas associated with volcanic activity is water vapor. A cinder cone is a type of volcano that is built almost entirely from ejected lava fragments. The pipe is the hollow center of the volcano. Factors Affecting Eruption Volcanoes can erupt explosively or mildly. They can erupt with lots of lava spewing out or slowly oozing out of the mouth. Some volcanoes erupt ash and dust with no lava at all. So what makes all of them so unique? Let's watch! Lets take a look at the factors that affect the eruption of a volcano. Factors Affecting Eruption Viscosity - _____________________________ ____________________________________. This means that something that has a high viscosity does not flow easily. A substance with a high viscosity would be honey. A substance with a low viscosity would be water. If the lava of a volcano has _________________ _____________________, the ______________ of a volcano will be _______________________. There are three factors that affect the viscosity of lava: ___________________, ______content, and _____________________. Factors Affecting Eruption 1.Silica the more silica in lava, the more ______________ it has. A magmas viscosity is directly related to its silica content. 2.Gas content - the more _____________ in lava, the ____________viscocity it has. 3.Temperature as temperature in lava increases, ______________________________. Example: heating up syrup. ***Bottom line: _____________________________ volcanoes tend to have magma with high _________, _________viscosity, and higher ___________content. Volcanic Material There are three main types of materials that come out of volcanoes: ________________________, _________, and _________________________________. Lava flows: 1.aa flow (AH ah): A lava flow with a surface of _________, jagged ___________and sharp, angular _______________. view here!view here! Think ow! it hurts to step on! 1.pahoehoe flow: lava flows that flow ______________ forming flows that look like twisted braids in ropes. view here! Gases: The most abundant gas associated with volcanic activity is ______________________. Volcanic Material Pyroclastic Material _____________________ _____________________________________ _ Pyroclastic materials include _______, ____________ and __________. These particles can range in __________ from fine dust to pieces that weigh several tons! Types of Volcanoes Anatomy of a volcano While there are several different types of volcanoes, each have a typical anatomy with the following parts: A.____________ B.____________ C.____________ D.____________ Types of Volcanoes The three main types of volcanoes are _____________cones, ___________volcanoes and ________________cones. ________________________ plays a major part in determining the __________of a volcano. Types of Volcanoes When you think about a typical volcano, what do you see? Usually a cinder cone highly explosive lava. 1.A cinder cone is a type of volcano that is built almost entirely from _______________ ___________. This give it a cone shape over time. Learn more here! Learn more here! Cinder Cone Volcano Cinder Cone from Pu'u'O'o eruption of Mount Kilauea Types of Volcanoes 2.Composite Cones a ___________________, symmetrical volcano composed of both _______ and __________________deposits. About Composite Cone Volcanoes Composite Volcano Mt. Shasta Types of Volcanoes 3.Shield Volcano have the shape of a broad, slightly _____________structure. Most shield volcanoes grow up from the ____________________ like the islands of Hawaii or Iceland. More about shield volcanoes Shield Volcano Iceland Check Ins 1.What is the viscosity of a lava/magma? 2.How does silica content affect viscosity? 3.How does gas content affect viscosity? 4.How does temperature affect viscosity? 5.What are the particles produced in volcanic eruptions called? 6.Name and describe the 2 types of lava flows. Objectives 3/10 I will be able to relate plate tectonics to volcanoes by describing where magma comes from, the types of boundaries that produce volcanoes. I will be able to graph the locations of volcanoes on a map and compare patterns of volcanoes to plate tectonics. Key Points Magma composition plays a major part in determining the form of a volcano. Magma forms when solid rock in the crust and upper mantle melts. The composition of the material, water content and confining pressure are factors that affect the melting point of rock. Magma tends to rise towards Earths surface primarily because rocks become less dense when they melt. Most of the active volcanoes on Earth are located in a belt known as the ring of fire. Identify an O-C plate boundary creating a volcano. How Volcanoes Form How Volcanoes Form Video Magma As we know, __________________________ plays a major part in determining the form of a volcano. But where does magma come from? Magma forms when solid rock in the crust and upper mantle melts. Magma How does rock melt? There are three factors that contribute to rocks melting, or the formation of magma. 1._______________ As you go ___________ in the earth, the temperature ___________. Subduction creates ______________and causing heat As magma rises, it heats rocks closer to the earths surface. But this alone is not enough to create all of the magma that we know exists below the earths crust Magma 2.Confining Pressure As confining pressure is __________________, the melting temperature of rocks is __________. This means that as rocks can melt easier as they are released from the confining pressure deep within the earth. This process is called _______________________. Magma 3.________________ ____________in rocks can cause a rock to melt at _________________________________. Rocks with more water in them melt easier than rocks that are dry. BOTTOM LINE: The __________________ of the material, _______________content and confining ________________are factors that affect the melting point of rock. Magma Now that we know how magma forms, why does it come to the surface of the planet? Lets discuss. Write down what you think: __________________________________ __________________________________ Magma Magma tends to rise towards Earths surface primarily because _______________________ ______________________________________ What does that mean? When rocks change from a solid state to a liquid state, they become lighter! What is lighter will rise, just like heavy things sink! Plate Tectonics and Volcanoes Most of the active volcanoes on Earth are located in a belt known as ______________ ______________________. Others are located seemingly sporadically around the globe. Scientists could not explain the worldwide distribution of volcanoes until the introduction of the theory of Plate Tectonics. The Ring of Fire Watch a slideshow of the Volcanoes on the Ring of Fire HERE!HERE Plate Tectonics and Volcanoes Plate movement forms volcanoes in three zones: 1.Convergent Plates Ocean Rising magma can form ____________________ in an ocean (Aleutian Islands). Ocean Continent Rising magma can form __________________________________________ (Andes Mountains). Convergent Boundary Volcano Mount St. Helens emitting volcanic ash 2 months after its May eruption in Was type of convergent boundary caused Mt. St. Helens? How do you know? Plate Tectonics and Volcanoes 2.Divergent Plate Boundaries When plates pull apart, there is less pressure on the rocks below. _______________________________________ ________________________________________. Plate Tectonics and Volcanoes 3.Intraplate Igneous Activity Intraplate means activity __________a tectonic plate _____________from plate boundaries. This is caused by Hot spots. Examples of this are the ____________________ Kilauea, an Intraplate Volcano Mapping Volcanoes Lab Follow the directions on the handout to map volcanoes around the world. After you finish plotting the volcanoes, answer the questions in complete sentences. Viscocity Lab You will be working in pairs to investigate viscosity today. 1 partner and ONLY 1 partner will need his or her laptop out. Once you are in your groups go to the following web address (also linked on the wiki)quids/visco_exp/en/viscosity.htm?width=620 &height=500&popup=truequids/visco_exp/en/viscosity.htm?width=620 &height=500&popup=true You will have 20 minutes to complete this- work efficiently!