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 ground due to the movement of plates at fault lines Most earthquakes occur along plate boundaries  Faults Fault:Break in earth's lithosphere where one block of rock moves toward away from or pass another block or rock  Faults Type of Fault Description Picture Strike slip Occurs at transform plate boundaries Normal Occurs at divergent plate boundaries Reverse Occurs at convergent plate boundaries  Earthquakes, Focus and Epicenter Seismic Waves: Energy that travels as vibration or and in earth Focus: a point inside earth where the earthquake first starts Epicenter: the location on earth's surface directly above the the focus  Types Of Seismic Waves Type Of Wave Description Picture Primary wave Travels in a push pull motion -Fastest moving seismic waves -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 aup and down motion Surface wave -moves in a rolling motion -slowest seismic wave -Causes the most damage to earths surface  Earth’s Interior How did scientists discover that Earth’s outer core is liquid? Scientist discovered that the earth's outer core is liquid because the s-wave cannot travel through liquids but p-wave can travel through both solid and liquids  Finding an Epicenter Triangulator 1.Find difference between the arrival time of the p-wave and the arrival time of the s-wave (lag time 2. Using earthquakes distance graph determine the distance from the epicenter 3. Draw a circle with the correct distance around the station. Repeat for two more stations 4. When the circles intersect is the epicenter 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 amount of energy scale released by an earthquake Modified mercalli Measures the intensity of an earthquake scale based on the amount of damage  Earthquake Risks Seismologist use 5 indicators to assess earthquake risk: 1. Past earthquakes 2. Proballtity 3. Population density 4. Geology around a fault 5. Building designs 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 wich molten rock forms Where do volcanoes Description form? Convergent Where two plates collide and one one plate subducts under boundaries another plate. This causes volcanoes to form Divergent boundaries Where two plates separate and magma comes out examples include mid ocean ridge and rift valley Hot spots Volcanoes that are associated with plate boundaries usually forms chains of islands like hawai  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 volcanoes 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 volcanoes depression created when the summit of the vocanes collapsed during a violent eruption  2 Types of Eruptions Type of Eruption Description Violent Lava has a high viscosity (thick lava ) eruptions Lava has a high gas content Quiet eruptions Lava has a low viscosity (thin lava) Lava has a low gas content 4 Effects of Volcanic Eruptions Effects Description Lava flows More slowly can destroy towns and are rarely dead Ash fall Cause breathing problems can cool earth’s atmosphere and can disrupt air traffic Mudflows Can cause snow and ice melt which mixes with mud ash and causes the mudflows Pyroclastic Can be deadly produced from violent eruptions and throw gas and rock into air flows  Predicting Volcanoes Ground deformation observed Increase in earthquakes Volcanic gas increases Water near the volcanoes can become more acidic  Climate How do volcanic eruptions affect climate? -volcanic ash blocks the sun and causes a decrease in global temperatures - can also cause and rain