Earthquakes and Volcanoes Notes - PDF

Earthquakes and Volcanoes  The BIG Idea What causes earthquakes and volcanic eruptions? Lesson 1: Earthquakes Essential Questions: What is an earthquake? Where do earthquakes occur? How do scientists monitor earthquake activity? Where Do Earthquakes Occur? Earthquake: vibrations...

Earthquakes and Volcanoes  The BIG Idea What causes earthquakes and volcanic eruptions? Lesson 1: Earthquakes Essential Questions: What is an earthquake? Where do earthquakes occur? How do scientists monitor earthquake activity? Where Do Earthquakes Occur? Earthquake: vibrations in the Earth’s ground due to the movement of plates at fault lines Most earthquakes occur along plate boundaries.  Faults Fault: Break in the Earth’s lithosphere where one block of rock moves toward, away from, or past a block of rock  Faults Type of Fault Description Picture Strike slip Occurs at transform plate boundaries. Normal Occurs at divergent plate boundaries Reverse Occurs the convergent plate boundaries.  Earthquakes, Focus and Epicenter Seismic Waves: energy that travels as vibrations on and in Earth. Focus: A point inside Earth where the earthquake first starts Epicenter: The location on Earth’s surface directly above the focus.  Types Of Seismic Waves Type Of Wave Description Picture Primary wave Travels in a push pull motion Fastest moving seismic wave Can travel through solids and liquids. Secondary wave Slower than P-waves, but faster than surface waves They only travel through solids Particles move in and up and down motion Surface wave Moves in a round motion Slowest seismic wave Causes most damage to Earth’s surface  Earth’s Interior How did scientists discover that Earth’s outer core is liquid? Scientists discovered that the Earth’s outer core is liquid because the S-wave can’t travel through liquids, but P-waves can travel through both solid and liquid.  Finding an Epicenter 1. Find the distance between the arrival time of the P-wave and the arrival time of the S-wave.[lag time] 2. Using an earthquake distance graph, determine the distance from the epicenter. 3. Draw a circle, with the correct distance around the station. Repeat for two more stations. How to Measure Earthquakes Type of Scale What does the scale measure? Measures the amount of ground motion Richter Scale at a given distance. Moment magnitude Measures the total amount of energy scale released by an earthquake. Modified Mercalli Measures the intensity of an earthquake scale based on the amount of damage. I-XII  Earthquake Risks Seismologist use 5 indicators to assess earthquake risk: 1. Past earthquakes 2. Probability 3. Population density 4. Geology around the fault 5. Building design. Lesson 2: Volcanoes Essential Questions: 1. How do volcanoes form? 2. What factors contribute to the eruption style of an earthquake? 3. How are volcanoes classified?  Volcanoes Volcano: a vent in Earth’s crust through which molten rock flows. Where do volcanoes Description form? Convergent Where two plate collide and one plate subducts under boundaries another plate. This causes volcanoes to form Divergent plate Where two plates separate and magma comes out. boundaries Examples include mid ocean ridges and rift valleys. Hot spots Volcanoes that are not associated with plate boundaries. Usually forms chains of islands like Hawaii.  3 Types of Volcanoes 1. Shield Volcano 2. Composite Volcano 3. Cinder Cone Volcano  Shield Volcano Shield Volcano: Large shield shaped volcanoes with gentle slopes and gentle eruptions.  Composite Volcano Composite Volcano: Large, steep sided volcano, that result from explosive eruptions.  Cinder Cone Volcano Cinder Cone Volcano: Small, steep-sided volcanoes that erupt gas rich, basaltic lavas. Moderately explosive eruptions  What is a Caldera? Caldera: Large volcanic depression created when the summit of the volcano collapsed during a violent eruption  2 Types of Eruptions Type of Eruption Description Quiet Lava has a high viscosity Lava has a high gas content Violent Lava has a low viscosity Lava has a low gas content 4 Effects of Volcanic Eruptions Effects Description Lava Flows Moves slowly, can destroy towns and are rarely deadly. Ash fall Cause Breathing problems, can cool earth atmosphere, and can disrupt air traffic. Mudflows Can cause snow and ice to melt which mixes with mud/ash and causes mudflows Pyroclastic Can be deadly, produced from violent eruptions, and throw gas, and rock into the air. Flow  Predicting Volcanoes Ground deformation observed Increase in earthquakes Volcanic gas increases Water near the volcano can become more acidic.  Climate How do volcanic eruptions affect climate? - Volcanic ash blocks the sun and cause a decrease in global temperatures - can also acid rain