Warm-up 11/3 & 71. 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

LithosphereAsthenosphere

Remember: Plate Tectonics1. 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 BoundariesTwo types of plates:1. Oceanic Plates 2. Continental Plates

Three types of boundaries:1. Collide2. Separate3. Slide past

Fault – Border of plate boundaries

Convergent Boundary

Plates collide3 types based on types of crust

colliding1. Continental-continental

◦Create mountains◦Examples

Convergent BoundarySubduction zone

◦More dense plate is pulled under (subducted)

◦Crust is melted down, produces magmaMagma rises to form volcano2 boundaries

Convergent Boundary2. Oceanic-oceanic

◦Older plate is subducted (more dense)◦Subduction forms trench◦Example

3. Continental-oceanic◦Oceanic is subducted◦Creates: Trenches Volcanoes

◦Example

Explosive Eruptions

Rare ◦Total number:

DestructiveProduce

◦Debris◦Ash◦Gas

Pyroclastic Flow

Pyroclastic FlowsLarge amount of

material produced in small amounts of time

Temperatures greater than 700 deg. Celsius

Faster than a hurricane

Lahar

Deadly

Divergent BoundaryPlates 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:

1. Convergent boundaries = Collide

2. Divergent boundaries = Dividing

Check for understandingIs the following picture:1. Convergent boundary2. Divergent boundary

Check for understandingIs the following picture:1. Convergent boundaries2. Divergent boundaries

Check for understandingIs the following picture:1. Convergent boundary2. Divergent boundary

Warm-up 11/101. 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

PhenomenonTheories

◦Mantle plumes◦Cracks in crust

Far from boundary◦Examples

Appear to move over time

◦Why?

Warm-up 11/11-12What 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 BoundariesPlates slide past each other No creation or destruction of crustNot a smooth movement

Earthquakes!

San Andres Fault

EarthquakesWhat are they? What is it like?SeismologistWhere?

◦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

Imaging of Earthquake Waves

Seismograph◦Measures and records local movement

◦3 main waves1. P wave2. S wave3. 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 EpicenterDistance 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-up1. 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 PredictionNot exactSeismic gaps

◦Area of fewer earthquakes

◦Likely location of future earthquake

◦Used to predict 1989 San Francisco

Past frequency

Destruction from EarthquakesLiquefaction

◦ Mixing soil with underground water

◦ Sinkholes LandslidesFire

◦ Broken gas and electrical lines

◦ Lack water to fight

Building and highway damage

Hand-Signals…Show me:

1. Convergent boundaries = Collide

2. Divergent boundaries = Dividing

3. Transform boundaries = Slide

What type of boundary is this?

TsunamiHow?

◦Displacement of a large volume of water

◦CausesMassive waves

◦Wavelength◦Height◦Period

Impacts coastline◦Wave slows◦Increases in

height

Tsunami warning system

Only a few a yearMost recent (major)

◦Indonesia (Dec. 2004)

◦Japan (Mar. 2011)Seiche

Ring of Fire