Selected Animations

Welcome! Thanks for visiting Poorna's pages at the Glendale Community College web site. You can learn here about my 'Earth Revealed' telecourse and the Physical Geology class, Environmental Geology (Lecture and Lab.) and Oceanography (Lecture and Lab.) classes. These pages, and the links therein, will also give you information about earthquakes, particularly the seismicity in Southern California, volcanism, plate tectonism, El Nino, global climate change, atmospheric and ocean circulation, energy and other earth resources, and the related environmental issues.
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Hurricane Katrina
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Tsunamis: Asian Tsunami, Tsunami from the Cascade Subduction Zone
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Plate Tectonics: Continental Drift, Lithospheric Plates, Sea floor spread, Farallon Plate, Active Plate Boundaries
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Updated on 09/26/2005
bullet The Hawaiian Hot Spot
       


Hurricane Katrina (http://www.ncdc.noaa.gov/img/climate/research/2005/katrina/katrina-satellite.gif)
 

 

The Dec 2004 Asian Tsunami:

The Dec 2004 Indian Ocean tsunami was produced by perhaps the strongest earthquake of the past 100 years. It occurred in the Java trench, off Bandar Aceh in north-western Sumatra. This image is a work of the National Oceanic and Atmospheric Administration

 
 
Cascade Subduction Zone:

Seismicity at the Filled Trench offers the most likely scenario of the western U.S. facing the kind of disaster that the Dec 2004 Asian tsunami, caused by the magnitude 9+ Sumatra earthquake of Dec 26, 2004, wrecked on the Indian Ocean coasts.
Juan de Fuca ridge and the associated plates and
plate boundaries off the Pacific North-east and Canada. Note that the Cascadia subduction zone is also called the “Filled Trench”, as this trench got filled by sediments carried by the huge runoff from land that has characterized this region particularly since the Last Ice Age.
   
Plate Tectonics:
Continental Drift, Sea Floor Spread, Convergent Tectonism etc.
   

This USGS animation of Wegener's "Continental Drift" postulate ...

  • begins with view of Earth with continents in their present positions,

  • continents move back in time to reunite as Pangea and the Pangea label appears, and then the

  • locations of stratigraphic and fossil evidence that Alfred Wegener used to argue in proposing his postulate of continental drift are added.

(Source: http://www2.nature.nps.gov/geology/usgsnps/animate/pltecan.html)
The Present Lithospheric Plates

Continental Drift since the Late Proterozoic
 

Farallon Plate?

"Demise of the Farallon Plate Beneath North America" (2001) by L. Han, E. Tan and M. Gurnis (GIF Size: 680Kbytes). Find out more by

reading about the science behind this movie.

(http://www.gps.caltech.edu/~gurnis/Movies/movies-more.html)

Farallon plate is not what we can now see for, much like Wegener's Pangea, most of it has subducted beneath North America. It's only parts that still remain exposed are the micro-plates (?) 'Juan de Fuca' and 'Cocos'.
   
   

Sea Floor Spread
 

USGS animation of how the sea floor spreads by intermittent volcanism at the mid-ocean ridge (right).
 

This results in the recording by subsequent lavas of the geomagnetic polarity reversals (bottom right) and the resulting marine magnetic anomalies can be mapped by magnetometers towed by ships (bottom left)

   
Active Plate Boundaries:

Active plate boundaries (i.e., the plate boundaries where the Earth's surface area changes) can be either 'divergent' (e.g., mid-ocean ridges, where new surface is created) or 'convergent' (e.g., where existing surface is lost, either at folded mountain belts, or at the deep sea trenches, or both, depending on the kinds of plate edges that are converging).

These three animations show how these boundaries form:

  • the ones on the right show convergent plate boundaries (top: folded mountain belt, bottom: deep sea trench and folded mountain belt) and

  • the one below shows the formation of a divergent plate boundary.

 
 
The Hawaiian Hot Spot

Animation and History of the Emperor Seamounts and Hawaiian Islands

This animation shows the formation of the Emperor Seamounts and the Hawaiian Island archipelago.  The arrow indicates the relative direction of the Pacific plate.  Note the direction of the plate changes at about 43 million years before the present.  The Pacific plate is currently subducting under the the North American plate forming the Aleutian trench just south of Alaska and the Kuril trench just east of the Kamchakta Peninsula.  Eventually, the Emperor seamounts and the Hawaiian islands will subduct and disappear into the mantle.  Note the position of the plates in the image below.  Note that this animation simply implies plate movement, the actual Pacific plate is spreading out from the East Pacific rise, some 3,000 miles east of South America.

Source URL: http://www.colorado.edu/geography/cartpro/cartography2/spring2001/campbell/final/anime_pg.html
 

 
 

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