Warm-up 11/3 & 7 1. What is it called when one plate goes under another plate? 2. What is it called where two plates separate? 3. What is one thing you know about volcanoes? 4. What is one thing you would like to know?

Plate Boundaries

Remember: Earth Structures Lithosphere Asthenosphere

Remember: Plate Tectonics 1. Plates are moving in different directions at different speeds. 2. Movement caused by convection in asthenosphere. Plate boundary = place where two plates meet.

Plates and Boundaries Two types of plates: 1. Oceanic Plates 2. Continental Plates Three types of boundaries: 1. Collide 2. Separate 3. Slide past Fault – Border of plate boundaries

Convergent Boundary Plates collide 3 types based on types of crust colliding 1. Continental-continental ◦ Create mountains ◦ Examples

Convergent Boundary Subduction zone ◦ More dense plate is pulled under (subducted) ◦ Crust is melted down, produces magma Magma rises to form volcano 2 boundaries

Convergent Boundary 2. Oceanic-oceanic ◦ Older plate is subducted (more dense) ◦ Subduction forms trench ◦ Example 3. Continental-oceanic ◦ Oceanic is subducted ◦ Creates:  Trenches  Volcanoes Volcanoes ◦ Example

Explosive Eruptions Rare ◦ Total number: Destructive Produce ◦ Debris ◦ Ash ◦ Gas Pyroclastic Flow

Pyroclastic Flows Large amount of material produced in small amounts of time Temperatures greater than 700 deg. Celsius Faster than a hurricane Lahar Deadly

Divergent Boundary Plates separate ◦ Space fills with magma ◦ Creates new crust ◦ Pushes old out 2 boundary types

Divergent Boundary 1. Continental-Continental or on Continental Plate ◦ Creates rift valley  May become lake  Examples

Iceland

Divergent Boundary 1. Oceanic-Oceanic ◦ Spreading center ◦ Mid-ocean ridge ◦ Majority of Earth’s volcanoes  Non-explosive

Nonexplosive Eruptions Most common Produce ◦ Calm lava flows ◦ Huge amounts of lava Shape our world ◦ Islands in the Pacific ◦ Sea floor

Hand-Signals…Show me: Show meShow me 1. Convergent boundaries = Collide 2. Divergent boundaries = Dividing

Check for understanding Is the following picture: 1. Convergent boundary 2. Divergent boundary

Check for understanding Is the following picture: 1. Convergent boundaries 2. Divergent boundaries

Check for understanding Is the following picture: 1. Convergent boundary 2. Divergent boundary

Warm-up 11/10 1. How are convergent and divergent boundaries similar? 2. Give a current example of a convergent boundary and what is being formed there. 3. What type of plate boundary is seen here  How do you know?

Hot Spots Phenomenon Theories ◦ Mantle plumes ◦ Cracks in crust Far from boundary ◦ Examples Appear to move over time ◦ Why?

Warm-up 11/11-12 What type of boundary creates mountains? Be specific. Radiometric dating is _________ dating. Which layer of the Earth is responsible for the movement of tectonic plates? The half-life of plutonium is 6530 years. A sample contains.39% of the original amount of plutonium. How many half- lifes have passed and how old it it?

Transform Boundaries Plates slide past each other No creation or destruction of crust Not a smooth movement Earthquakes! San Andres Fault

Earthquakes What are they? What is it like? Seismologist Where? ◦ Plate boundary ◦ Occur at or create faults ◦ Varying depths ◦ Focus  Epicenter

How are earthquakes measured? Richter scale ◦ Strength (magnitude) ◦ Measuring ground motion ◦ Used by the media Moment magnitude ◦ More precise ◦ Measures the energy released ◦ Measured at the epicenter ◦ Used by scientists

Largest Recorded Earthquakes Recent earthquakes Tracker Recent earthquakesTracker

Imaging of Earthquake Waves Seismograph ◦ Measures and records local movement ◦ 3 main waves 1.P wave 2.S wave 3.Surface waves

Earthquake Waves P waves ◦ First detected ◦ Back-and-forth S waves ◦ Side-to-side ◦ Slower, arrive later

Surface ◦ Rolling ◦ Side-to-side ◦ Close to surface ◦ Slowest ◦ More destructive Aftershocks Foreshocks

Finding the Epicenter Distance vs. time graph is constant ◦ Closest has smallest time difference Measure time difference on local seismograph ◦ Compare to graph ◦ Find distance Repeat for multiple locations

Finding Epicenter continued… Use distances found Draw a circle from each site Overlap = epicenter

Warm-up 1. Which type of plate boundary do you think has the greatest impact on society? Justify your answer. 2. If the S wave of an earthquake arrives at 10:45 am and the P wave arrives at 10:55 am, how far are you from the epicenter?

Earthquake Hazard Map

Earthquake Prediction Not exact Seismic gaps ◦ Area of fewer earthquakes ◦ Likely location of future earthquake ◦ Used to predict 1989 San Francisco Past frequency

Destruction from Earthquakes Liquefaction ◦ Mixing soil with underground water ◦ Sinkholes Landslides Fire ◦ Broken gas and electrical lines ◦ Lack water to fight Building and highway damage

Hand-Signals…Show me: Show meShow me 1. Convergent boundaries = Collide 2. Divergent boundaries = Dividing 3. Transform boundaries = Slide

What type of boundary is this?

Tsunami How? ◦ Displacement of a large volume of water ◦ Causes Massive waves ◦ Wavelength ◦ Height ◦ Period Impacts coastline ◦ Wave slows ◦ Increases in height

Tsunami warning system Only a few a year Most recent (major) ◦ Indonesia (Dec. 2004) ◦ Japan (Mar. 2011) Seiche

Ring of Fire