Previous Animations of the Month
Previous Animations of the Month can be found on the archive page.
Related Animation
If you cannot view the YouTube videos below, click the links next to them labeled "Direct Link to Animation" to view the videos using Quicktime Player.
Introduction
When two tectonic plates try to slide past each other there is generally such high friction that the areas on either side of the fault deform due to strain and stress. This is because even brittle rocks can behave elastically under slow steady pressure (see video lecture "Video Descriptions of the Model" in box to right).
Elastic rebound theory in plate tectonics was introduced in 1906 by H.F. Reid (link below) to explain how energy is released during earthquakes. When the amount of friction is suddenly overcome, the plates jump past each other and snap back, more or less, to their original undeformed shape. During the process the stored energy produces earthquakes. This released elastic energy is turned into kinetic energy, heat, and seismic waves. Large earthquakes can propagate seismic waves throughout the globe.
Elastic Rebound Animations & Video Clips
Animation shows the buildup of stress along the margin of two stuck plates that are trying to slide past one another. The rock is deformed as it builds up strain in the plates; stress increases along the contact.
Direct Link to High Friction Zone (Small 522kb)
Direct Link to High Friction Zone (Larger 580kb)
Animation of above adds trees to emphasize motion after the fault slip. At this scale, all the trees would shake, but here we only show shaking of the trees that were on the deforming parts of the plates immediately adjacent to the fault.
Direct Link to Rebound Trees (Small 280kb)
Direct Link to Rebound Trees (Larger 1.5mb)
Real Trees Shake in Quake
Actual video footage of a grove of oak trees taken by a USGS camera on Sep. 28, 2004. The camera, stationed along the San Andreas Fault, is part of a monitoring effort to increase our understanding of earthquake behavior. This camera records a snapshot image every 5 minutes until ground motion triggers the video camera to record continuously. About 6 seconds into the clip the M6.0 Parkfield earthquake shakes the ground.
Direct Link to Real Trees (Small 784kb)
Video Lectures about Elastic Rebound
Elastic Rebound Demonstration
Video lectures of Dr. Robert Butler, University of Portland speaking to middle-school teachers about elastic rebound and brittle material.
Direct Link to Lecture (Large 2.6mb)
Elastic Rebound Talk
Video lecture by Ross Stein of the USGS exerpt from the video, Shock Waves: 100 Years After the 1906 Earthquake directed and produced by Steve Wessels of the US Geological Survey.
Direct Link to Lecture (Large 2.6mb)
Additional links to Elastic Rebound
- H.F. Reid's Elastic Rebound Theory
- Introduction to Elastic Rebound Animation
- Download activity from University of Washington's Burke Museum of Natural History and Culture (PDF)
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Animations By Jenda Johnson
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