Lesson Summary
- During an earthquake, the ground shakes as stored up energy is released from rocks.
Nearly all earthquakes occur at plate tectonic boundaries and all types of plate bound-
aries have earthquakes. - The Pacific Ocean basin and the Mediterranean-Asiatic belt are the two geographic
regions most likely to experience quakes. The seismic waves that do the most damage
are surface waves, which only travel along the surface of the ground. - Body waves travel through the planet and arrive at seismograms before surface waves.
Tsunamis are deadly ocean waves that can be caused by undersea earthquakes.
Review Questions
- What is an earthquake’s focus? What is its epicenter?
- Why do most earthquakes take place along plate boundaries?
- Using elastic rebound theory, describe what triggers an earthquake.
- Use plate tectonics theory to describe why are there far more earthquakes around the
Pacific Ocean than anywhere else on Earth? - Since intraplate earthquakes are not near plate boundaries, give a general idea of what
you think might cause them. - Do the largest earthquakes cause the most deaths and the most damage to property?
- California is famous for earthquakes along the San Andreas Fault zone but there is
another type of plate boundary where large earthquakes occur. What type of plate
boundary is it and where the earthquakes likely to occur? - Using what you know about plate tectonics and elastic rebound theory, describe what
is taking place in the Cascades Mountains of the Pacific Northwest, including northern
California. What is likely to occur in the future? Include earthquakes and tsunamis. - What type of faulting is found where two slabs of continental lithosphere are converg-
ing? Explain what this would look like on a diagram of the faults and the rocks on
either side. - What are the characteristics of body waves? What are the two types?
- WhatmaterialscanP-wavestravelthroughandhowfastarethey? DescribeaP-wave’s
motion. - What materials can S-waves travel through and how fast are they? Describe an S-
wave’s motion. - How are surface waves different from body waves? In general, which type of waves is
more damaging in an earthquake? - What did Tilly Smith notice on the beach in Thailand that caused the adults around
her to evacuate the beach before the enormous tsunami hit in 2004? How were these
signs evidence of a tsunami?