E3.P3XB Unit Plate Boundaries and Earthquakes

Types of Plate Boundaries Divergent Transform Convergent

Assignment Students are to draw a table BoundariesCorresponding Faults Surface Features Examples Convergent Transform Divergent

What are Earthquakes? Red Book Chapter 8 Section 1

Where Do Earthquakes Occur?

Where do Earthquakes Occur? Seismology- the study of Earthquakes According to the previous map, where do Earthquakes occur? Answer: Earthquakes occur along fault lines due to the continuous movement of the Earth’s tectonic plates The Largest Quakes occur due to the Pacific Plate!

What phenomenon causes the Earth’s Tectonic Plates to be in constant motion? Answer: Convection Currents of the Mantle

What Causes Earthquakes? The push, pull, and grinding of tectonics plates against one another frequently causes deformation of those plates Deformation- the change in the shape of the rock as a response to tectonic motion – There are two types of deformation

Deformation 1.Plastic Rebound The plate is deformed and takes on a new shape – As if you were molding clay Plastic Rebound does not cause Earthquakes 2.Elastic Rebound The plate is deformed to a “breaking point” and snaps back into its original shape or position with a great release of energy Elastic Rebound causes Earthquakes

Elastic Rebound has been known to leave evidence such as displaced fence lines

All Are Earthquakes the Same? Plate Motion/ Boundary Fault TypeSurface Features Earthquake Characteristics Transform Strike-Slip“San Andres Fault” Moderate with Shallow Waves Convergent Reverse/ NormalMountains and Volcanoes Strong with Deep Waves Divergent None, there is no contact Mid-Ocean Ridges Weak with Shallow Waves

How Do Earthquakes Travel? Seismic Waves- Waves of energy that travel through the Earth – Primary P Waves – Secondary S Waves

Body Waves – Waves that travel in the interior of the Earth – P and S waves are Body Waves Surface Waves – Waves along that surface of the Earth that move the ground just like the ocean waves

Assignment 1.Where do Earthquakes occur? 2.How do convection currents play a role in causing Earthquakes? 3.What form of deformation causes Earthquakes and offsets fence-lines? 4.Name the plate boundaries/motions from weakest to strongest pertaining to Earthquakes. 5.Why are Surface Waves more destructive to buildings than P and S waves?

Measuring Earthquakes Chapter 8 Section 2

Locating Earthquakes Seismographs- measure seismic waves Seismogram- unit of measurement as recorded by a seismograph What is the name of the Scientist who studies Earthquakes?

Seismologists study Earthquakes Earthquakes happen with Elastic Rebound – The SNAP! The seismograph starts recording at the start of the quake – The more movement, the bigger the quake! By comparing the P and S Waves on the machine, exact start time can be determined Which Types of Wave Arrives First? P-Waves arrive first. P for Primary! They are faster because they travel through all types of matter: Solid, Liquid, and Gas

Focus- Earthquake’s starting point in the body of the Earth Epicenter- location on the crust directly above the focus – Seismographs can also help to find the focus

Scientists can see how far the Earthquake has traveled in a certain amount of time to locate the epicenter

Finding the Epicenter 1.Circles are drawn around each effected seismograph station

2. Circles for each station have an overlapping point

3. When all circles are drawn, they all intersect at only one point. This spot is the Epicenter!

Measurement Methods Richter Scale – Invented by Charles Richter – , bigger numbers for bigger damage Momentum Magnitude – Records amount of energy released – For every 1 pt on the Richter scale the energy released is 31.7 times more If an Earthquake is measured at a 3.5 Richter, what is the Momentum? 3.5 x 31.7 = units Richter X 31.7 = Energy Units

Assignment 1.What is the difference between seismograph and seismogram? 2.At least how many seismograph stations are need to locate an epicenter? 3.What is the difference between the Momentum Magnitude and the Richter Scale? 4.If an Earthquake is 7.0 on the Richter Scale, what is if on the Momentum Magnitude? 5.Which types of waves travel faster? Why?

Earthquakes and Society Chapter 8 Section 3

Earthquake Hazard Earthquake Hazard- How prone an area is to receive Earthquakes – Determined by past and present seismic activity Find where we live. Do we have a high or low hazard level ?

Earthquake Forecasting What do you think it means to Earthquake Forecast? Answer: The practice of predicting when and where Earthquakes will occur! Seismologists have discovered patterns in Earthquake activity that allows for predictions Fault zones are closely monitored for seismic activity

Worldwide Earthquake Frequency Chart Which type of Quake is less prevalent? Most prevalent?

The Gap Hypothesis – active faults with few quakes are likely to have strong quakes Seismic Gaps – areas along a fault where few quakes have occurred

Seismic Gap Hypothesis helped seismologists determine the time, place, and strength of the 1989 San Fran Quake

Earthquakes and Buildings When the ground shifts, the center of gravity for a building shifts, and the building falls Earthquake resistance buildings: – Mass Damper- weight on roof to stop movement – Cross Braces- strengthen the floors – Flexible Pipes- prevent breaks – Active Tendon- base weight to stop movement – Base Isolators- absorb seismic waves

Mass Dampers can be metal weights or water filled tanks

Are You Prepared? Before Shaking Starts – Put heavy objects on low shelves Less likely to hit anyone if they fall – Designated meeting spots Communication lines will be out – Stashes of flashlights, water, canned foods, batteries, first aid, fire extinguisher

When Shaking Starts – Crouch/lay under sturdy table/desk – Cover your head with your hands – Remain in your vehicle

After Shaking Stops – Be wary of aftershocks and fire, glass, other hazards – Meet family at designated area

Assignment 1.How is an area’s Earthquake Hazard determined? 2.Describe three ways to reinforce buildings. 3.Name four items to store in case of an Earthquake. 4.Where is the safest place to be during an Earthquake? A highway, times square, or the top bowl at Ford Field. Why? 5.What is gap hypothesis and how does it forecast Earthquakes? 6.Draw the 3-part Earthquake safety procedure.

The Impact of Earthquakes

Natural Disasters Earthquakes can cause many disasters such as: – Tsunamis – Landslides/Mudslides – Avalanches – Fires from gas leaks – Floods

WEIRD! We know that many quakes occur on the West Coast of the US, but did you know that the Mid-West and East Coast can feel them, too?! In 1811, four HUGE quakes rocked Missouri, causing the Mississippi to run backwards. The waves traveled all the way to Boston and rang the church bells!

Assignment What are the disasters causes by quakes? What is the safety procedure for both in cars and in builds? Additional Worksheet