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 Earth’s lithosphere where one block of rock moves toward, away from, or past another block of 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 vibrations on and in Earth. Focus: a point inside Earth where the earthquake first starts. Epicenter: The location in Earth’s surface directly above the focus.  Types Of Seismic Waves Type Of Wave Description Picture -Travels in a push pull motion P. Waves -Fastest moving seismic waves -can travel through solids and liquids -Slower than p-waves, but faster S. Waves than surface waves. -They only travel through through solids -Particles move in an up and down motion -Moves in a rolling motion Surface Waves -Slowest seismic wave - Causes the most damage to  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-waves can travel through both solids and liquids.  Finding an Epicenter Triangulation 1. FInd the difference between the arrival time of the p-wave and the arrival of the s-wave. (Lag Time). 2. Using 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. 4. Where 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 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 a 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 plates 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 Example includes mid-ocean ridge and rift valleys Hotspots Volcanos that are not associated with plate boundaries. Usually forms chains of islands like Hawii.  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 volcanic depression created when the summit of the volcano 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 Move slowly, csn destroy towns, and are rarely deadly Ash Fall Cause breathing problems, can cool Earth’s 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, ash 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 causes a decrease in global temperatures - Can also cause acid rain