PHYSICAL WORLD ESCI 243  -  NICHOLS COLLEGE ONLINE COURSE

Professor Mauri S. Pelto, 508-213-2168 peltoms@nichols.edu   

Plate Tectonics

Home Page Plate Tectonic Setting Earthquakes Volcanic Hazards Glaciers-Sea Level Rise Coastal Management
Water Resources Groundwater Management Global Warming Fossil Fuel Resources Alternative Energy Sources River Types-Flooding

Plate Tectonics explains the movement and interactions of plates on the surface of the earth.  The earth is comprised of plates, each moving at its own relative speed and direction.  The illustration on the right indicates the movement of continents over the last 750 million years. 

Reading: 48-64 Each assignment block requires reading the appropriate chapter and web assigned material and answering the  key concept questions and submitting those answers. I also expect two questions to be submitted from each chapter from each student on material that was either unclear or led you to further thinking.  I will answer these for the entire class to see on the discussion board.  So post your questions there.

Reading: 70-93  Each of the  assignment block will require reading the appropriate chapter and web assigned material and answering the  key concept questions. I also expect two questions to be submitted from each chapter from each student on material that was either unclear or led you to further thinking.  I will answer these for the entire class to see on the web page or in an email. 

Concept Questions:

1.Using the Richter Scale explain what magnitude earthquake is required to inflict significant damage?

2:  What are the two types of the earth's crust and how do they differ?  Why are the oldest rocks found in the continental crust region?

3. What are the six tectonic settings and the hazards of each?

4.How many earthquakes have occurred in Massachusetts and Oregon from 1990-2001.(State Earthqauke Maps).  Why the difference?

Assignment:  Examine this week's Earthquake Bulletin and determine the tectonic setting of the largest 10 earthquakes for this week.  Create a table as noted below to convey answer. Which setting has been most active?  Click on the link of each quake on the location on the right to see the area map to determine setting, below this map is a link to historic seismicity that shows all local earthquakes this is the map to compare to the key below on this page.

Sample table

Location Magnitude Setting
Iceland 3.3 Hot spot
Costa Rica 4.8 Subduction

Notes:

There are six plate tectonic settings.  Each is unique and identifies the earthquake and volcanic hazards for the region.  Utilize the below examples as your key for identifying the tectonic setting of the earthquakes.

Continental Collision:  A region where two sections of continental crust collide, building a mountain range.  This area has no subduction and no volcanic activity, but considerable earthquakes activity.  As the map indicates this setting is typified by a mountain region with widely scattered shallow earthquakes.  
Subduction Zone: A region where a section of oceanic crust is pushed underneath another section of crust.  The result of this bending of crust and driving it downward into the mantle is melting of the crust and considerable volcanic activity.  The bending and slipping downward of the crust is a jerky process leading to many large earthquakes.  This setting is associated with linear volcanic mountain belts.  This setting is the only one with deep quakes blue-red in color.
Mid-Ocean Ridge:  This linear feature is often in the middle of the ocean, as in the Atlantic Ocean, but not always, note Pacific Ocean.  This feature is submarine and is where new ocean crust is formed replacing that lost through subduction.  It leads to the spreading open of oceans and has moderate earthquake activity and considerable submarine volcanic activity, but does not form true volcanoes.  All the quakes line up along the mid-ocean ridge and are shallow.
Transform Fault: These long straight features, offset sections of the Mid-Ocean Ridge.  As such it is a boundary across which two sections of crust move differently.  The resulting friction causes considerable earthquake activity, but no volcanism. These quakes are linear but not as narrowly focussed as on a mid-ocean ridge.
Hot Spot:  An isolated point of volcanic activity.  These are stationary points that produce outpouring of lava and form shield volcanoes.  There is little substantial earthquake activity. Small quakes clustered in a single area.
Passive Zone:  These areas are remote from any plate boundary and have no volcanoes, and infrequent earthquakes.  Very few earthquakes with nearly random distribution.