Earthquakes March 30, 2011

Key Concept #1  The driving force behind all crustal movement on Earth is convection currents within the mantle. The energy for this force is provided by radioactive (nuclear) decay.

Key Concept #2  An earthquake is a natural rapid shaking of the lithosphere (land) caused by the release of stored energy in rocks.

Key Concept #3  Earthquakes are measured using two types of scales. __________________ Scale Measures: Damage MercalliRichter Intensity

Key Concept #4  A tsunami is a large wave produced by a disruption of the ocean floor. Ex: faulting, landslide

Earthquake Terminology

Key Concept #5  Energy is released as seismic waves (earthquake waves). P - wave S - wave Also called: Primary or Push-Pull Also called: Secondary Travels Through Solid, Liquid, and Gas Travels Through Solid only! Speed: Fast Speed: Slow

“Earthquake P-wave and S-wave Travel Time”

Exercise #1: How far will each wave travel? Each Travel Time Box = 20 seconds Each Distance Box = 200 km P S

Exercise #2: How fast will each wave travel? Each Travel Time Box = 20 seconds Each Distance Box = 200 km P S

Difference in Time Practice #1 P-wave Arrival Time = 1:15:00 S-wave Arrival Time = 1:18:30 Calculate the difference in time: SHOW YOUR WORK! Practice #2 P-wave Arrival Time = 3:38:45 S-wave Arrival Time = 3:41:30 Calculate the difference in time: SHOW YOUR WORK!

Earth’s Interior Scientists infer most of the properties of Earth’s interior through the study of seismic (earthquake) waves. Remember: P-waves can travel through anything, while S-waves can NOT travel through liquids.

S-Wave Shadow Zone How can scientists infer Earth’s interior structure based on seismic waves?

Exit Ticket Why can’t I dig to China? Create a comic strip or short story about our journey to the center of the Earth.

What is the Theory of Continental Drift?

Alfred Wegner, 1915 The continents were once a super-continent called Pangea. The continents are plowing through the ocean floors---most people didn’t believe this.

What evidence supports this theory? Africa & South America look like they fit together like a puzzle. Similar fossils, rocks, and glacial striations.

What is the Theory of Plate Tectonics? Earth’s crust is made up of plates that ride on top of the asthenosphere. The plates move due to convection currents in the mantle.

What evidence supports this theory? Distribution of Earthquakes and Volcanoes. Sea floor spreading.

heat 1. As the water is ______ it becomes _________ and _______ 2. On reaching the surface the water ______ in contact with the air. 3. As the water ______ it becomes _____ _______ and ________ 4. A cycle develops, we call this a __________ ________ or cell. Convection Current Example heated less dense Rises. cools more dense sinks. convection current

How do oceanic and continental crust compare with regard to thickness and density? continentaloceanic Density (ESRTs pg 10) Thicknes s

What are the primary rocks which make up the continental and oceanic crusts? Continental crust Oceanic crust High density, dark- colored, fine-grained, mafic igneous rock Low-density, light- colored, coarse-grained, felsic, igneous rock

What are these types of plate boundaries? What are the key characteristics for each? Give an example of where each can be found.

What happens to the age of oceanic crust as distance increases from a ridge?

Explain how magnetic data can be used to show that oceanic crust is diverging at ridges. Use the diagram below to help explain your answer. diagram As new crust is made at ridges, the ferrous minerals (Fe) align according to where the magnetic poles are located Same pattern on opposite sides of the ridge Proves sea-floor spreading