THE EARTH’S PLATES The Earth is made up of several plates There are about a dozen major plates and many minor plates These tectonic plates move at different rates that vary between as much as 15 cm/year to as little as 2.5 cm/year Most plates are partly continental and partly oceanic
FAULTS IN THE EARTH • A fault is a fracture between two plates. • Have you ever “broken” a bone? Or known someone who has “broken” a bone? What did the X-ray look like? This is an easy way to think of a fracture. • A fault is like a gap between two plates and is usually an area where many earthquakes can be expected. • Faults are usually about no more than 16 km deep. • Faults have friction and it resists plate movement that increases stress. The release of the stress causes earthquakes.
Let’s Feel a Fault! • Step 1- Put your hands together like you’re about to clap. • Step 2- Push your hands together as hard as possible! • Step 3- Try to slowly move your hands from side to side while pushing them together. The pressure from pushing them together creates friction.
SAN ANDREAS FAULT • One of the most famous faults on earth is the San Andreas Fault • This fault effects areas of San Fransicso, Los Angeles, California and the rest of the U.S.
PLATE MOVEMENTS • There are three different kinds of plate movements that can result in earthquakes. • 1. Divergent plate movement • 2. Convergent Plate movement • 3. Transformational plate movement
DIVERGENT PLATE MOVEMENT This type of plate movement is common in the ocean.
CONVERGENT PLATE MOVEMENT When dense oceanic plates collide and go under continental plates
TRANSFORMATIONAL PLATE MOVEMENT This is the most common type of movement that causes the earthquakes felt my humans. The San Andreas Fault is a good example of Transformational plate movement.
EARTHQUAKES CREATE SEISMIC WAVES What happened when the water was dropped into the bowl of water? This is like a seismic wave. Seismic waves shake the ground as they pass. This is why earthquakes can be felt from many, many Kilometres away!
HOW TO MEASURE AN EARTHQUAKE The most common and reliable measurement of an earthquake is to measure it by the Richter Scale. The Richter Scale developed in 1935 by Charles Richter and his partner Beno Gutenberg . The Richter Scales measures earthquakes from 1.0 to 9.0
THE RICHTER SCALE • 1.0 – You can’t even feel these earthquakes. These earthquakes occur below the ground. • 2.0-Trees may sway, small ponds ripple but you really can’t tell that these things are happening because of an earthquake. • 3.0- These earthquakes can be noticeable if you are sitting still or in the upstairs in a house. May slightly move pictures on walls. • 4.0 It feels like a truck just passed your house. The buildings shake a little • 5.0- Glasses and dishes might rattle, or a car may rock. Sometimes, windows may break
THE RICHTER SCALE • 6.0- Pictures can fall off walls, furniture moves and walls might crack • 7.0- It is difficult to keep your balance! Ground shakes and roads crack. Weak buildings fall down and other buildings are damaged. • 8.0 Very serious. Very few buildings stay standing. Bridges fall down. Railroad tracks bend. Underground pipes burst and objects can be swallowed up by the earth. • 9.0- biggest earthquakes ever measured. Causes complete devastation and several losses of life.
SHOW WHAT YOU KNOW • 1. What is a fault in the earth? • 2. What is one of the most famous faults? • 3.What is the most common type of plate movement? • 4.Give an example of a way to think of a seismic wave • 5.What is the Richter Scale used for? • 6. At what point on the Richter Scale are earthquakes considered to be more serious? • 7. Does Canada get earthquakes? Why or Why not?
EARTHQUAKE VIDEO http://video.nationalgeographic.com/video/player/environment/environment-natural-disasters/earthquakes/earthquake-101.html