This 3-D rotatable view shows the double-couple focal mechanism from the University of Washington regional seismograph network solution (PNSN polarity observations) as a focal ball (convex) centered at the hypocenter location of the Nisqually earthquake, along with approximately 1350 earthquakes located with a 3-D regional velocity model from inversion of explosion (SHIPS, ...) and earthquake data. Note that the Nisqually earthquake hypocenter depth is revised here to 58 km, deeper than the initial PNSN network location at 51 km, based on reanalysis with both 1-D and 3-D models. Compressional quadrants are colored black and dilatational quadrants are yellow. The diameter of the focal sphere is 15 km, making the cross-section of the focal ball approximately equal to the estimated rupture area of faulting. Regional earthquakes are located with a current high-resolution 3-D P wave velocity model derived from earthquake arrival times and SHIPS experiment observations. Hypocenters of earthquakes interpreted to be in the subducted Juan de Fuca slab are colored BLUE , and the hypocenters of earthquakes interpreted to be in the continental crust are colored RED .
The LiveGraphics3D display above allows interactive control in a
Java-enabled browser.
Click-and-drag the figure using a trackball paradigm to change the
viewpoint in real time.
Note that the Cartesian axis distances are in km relative to an
arbitrary origin
of coordinates. Green lines are lat/lon grid lines at half degree
intervals.
All hypocenter symbols are drawn at the same size.
Java must be enabled in your browser for this application to work.
Rotate the object to a new viewing angle by click-dragging over
the image (left mouse button).
Zoom by shift-click-dragging left mouse button while moving the mouse
vertically.
Rotate the image about a vertical axis normal to screen by
shift-click-dragging horizontally.
Change the focal point by ctrl-click-dragging vertically.
This page is created using LiveGraphics3D by Martin Kraus (
http://www.vis.uni-stuttgart.de/~kraus/LiveGraphics3D/).
General SHIPS results from the UW and other research groups is being made available on the WEB at: http://www.geophys.washington.edu/SEIS/SHIPS (Contact: Bob Crosson - crosson@u.washington.edu - for more information)