Hi All. Sometime ago Lowell had told me about a change in direction of movement of the Pacific Plate. I didn’t remember all of the particulars so I e-mailed him requesting him to repeat what he told me.

While waiting for his reply I went to Tanya Atwater’s web site and downloaded her movie of the movement of the Pacific Plate. It appears that most if not all of the driving force for the Pacific Plate is off the coast of Central and South America.

Tanya Atwater is currently Professor of Geology at UCSB.

Here is Lowell’s reply to my questions. Take Care…Don in creepy town

Take a look at the Hawaiian island chain - or any other chain in the south Pacific, like the Society Islands, for example.

Near Wake Island, the Hawaiian Island chain takes an abrupt turn from North to south to more west to east. This occurred 40 million years ago at the time of a strong meteor impact which changed the direction of plate movements by causing a hot spot to form which changed the sea floor topography and thus the motion of the plates. Remember, that the Pacific plate is moving as one complete piece, so as it moves over a hot spot
(which is assumed to be stationary, but really is moving only slowly), volcanos form over the hot spot. As the plate moves the hot spot hits the plate in a different place, so you can
follow the motion of the plate by following the progression of volcanic islands in their formation in time.

The hot spot is currently located beneath a seamount south of Hawaii. Up until the formation of the island of Hawaii about 2 million years ago, the plate moved in a generally W-E direction, but about 2 million years ago a large meteor hit in the region near the Philippines, changing the motion of the plate (it is now moving more to the north (i.e. the islands are forming from north to south)) than it was several million years ago.

You may have to take two sheets of paper to understand this. Make a dark spot on one of them and place it under the other. The dark spot represents the position of the hot spot which is forming volcanic islands. Now place the second sheet over the piece with the dark spot, and start moving it in a straight line, making a mark (representing a volcanic island) every 5 seconds while moving the upper sheet slowly in any given direction. Now apply a force to your hand (perhaps by pushing it with the other hand) and see what happens to apparent motion of the upper plate. This represents the change due to any number of things, (meteor impacts, mountains trying to subduct etc.).