continents that moved (North
America, South America, Antarctica, Australia, India,
directly away from one unique central point.
It is just north of Madagascar in the Western
Somali Basin, centered on Wilkes Rise and the
that central point is a feature unlike any other
on the ocean floor. It appears to be a giant crater.
pictures to enlarge
The Earth flexes as the Moon revolves around it. The
place where it is the least flexible is shown in dark
blue below. Something has changed the layers deep
below the surface there, and geologists have no idea
why. But it is right over the giant crater.
This solid Earth (body) tide
projection was "generated from the actual history of the tidal
forcing". It is a measure of elasticity.
The image was computed using the 3-D model SPRD6 of
Ishii and Tromp. --Latychev, Konstantin, Jerry X. Mitrovica,
Miaki Ishii, Ngai-Ham Chan, James L. Davis. 2009. Body tides on
a 3-D elastic earth: Toward a tidal tomography. Earth and
Planetary Science Letters, Vol. 277, No. 1-2, pp. 86-90.
"The tidal response
of the Earth reveals a great deal about its inner structure."
"The calculations show that the perturbation in surface
deformation is large, with contributions from both elastic moduli
and density heterogeneity." --Ishii, Miaki, Konstantin
Latychev, Jerry X. Mitrovica, Ngai-Ham Chan, James L. Davis. Body
Tides on a Three-Dimensional Elastic Earth: Toward a Joint Tidal
and Seismological Tomography. American Geophysical Union, Fall Meeting
2008, abstract #DI11A-08.
In their original positions next to the crater,
the coasts of Africa, Madagascar, and Australia are
brown segment shows the former position of the Horn
Around the crater are features made by powerful
Minor mountains on the continents that moved are
on the side nearest the crater.
original position is as in 3. above, with Southeast
Asia attached to what is now northwest Australia)
Major mountains are on the side farthest from
If continental crust were being carried about
on brittle plates, even though it is flexible it would
keep its shape. But if continental crust slid
on top of a stationary surface, it would stretch
and bend, especially where it is narrow.