....Seismicity,
Pacific Extrusion and Asian Torsion.
....Seismicity,
Pacific Extrusion and Asian Torsion.
| The huge imbalance in seismic activity between the spreading ridges and subduction zones is simply explained in an expanding Earth. Those around the circum-Pacific and the panhandle of the Alpine Himalyan region express the tectonics of adjustment of curvature of the Pangaean hemispheres to an enlarging substrate whilst those at the spreading ridge express growth, ..not 'tectonism'. Plate Tectonics with its balance of creation and destruction implies a rough equivalence in release of seismic energy and has no real explanation for this imbalance. |
Fig.1 Dilation of Pangaean hemispheres by Pacific extrusion. Three-dimensional view shows the remarkable imbalance in seismicity between the circum-Pacific margin and the spreading ridges to be due to torsional adjustment of Pangaean hemispheres. (a) = no rotation of southern hemisphere; (b) southern hemisphere rotated 90 degrees east ('Indonesian megashear' of Carey); (c) = seismic activity; earthquakes recorded since 1963. Red bulge represents Pacific mantle extrusion,
The thick black zone of seismic activity around the continental Pacific margin reflects a crustal adjustment peculiarly intrinsic to the margins of the Pangaean hemispheres, and cannot be explained as some sort of corollary effect of ridge growth, since transform faults which record that growth are not subducted, i.e., transform faults do not reach as far as the subduction zone. This is the case at least along the Western Pacific Margin ( 1 ). The Eastern Pacific margin is overriden by movement related to Atlantic spreading, and is non-diagnostic, but the point is clear for the Western Pacific - there is no subduction in the sense that Plate Tectonics means it - related to a cycling cell. Movement (and seismicity) is simply an edge effect between the ruptured Pangaean earth and the newly created mantle as the Pangaean crust continues to swivel open to accommodate the extrusion of the Pacific ( 2 ).
Certainly continental margins are related to spreading ridges, but not in the way Plate Tectonics says, ...as corollary brittle expressions of ductile cell movement. It makes no sense to say that 200km or so thickness of crust to a depth bending down to nearly a thousand kilometres and causing partial melting to give the Fiery Ring of the Pacific, is more brittle ('colder-therefore-subducting') than the crust of the spreading ridge, which doesn't have a single volcano on it*. There are large volcanoes on marginal transform fault sectors, but none directly on the ridge itself, and nothing nearly comparable to the circum-Pacific, which is the locus of Pangaean dilation. Rather they are related simply as shown in the figure where ridge growth is balanced by the torsional adjustment of Pangaean opening ( 3 ), ..not subduction. (The Mediterranean to Himalayan region is the hinge of hemispherical opening ( 4, 5 ) )
(*Note, Iceland volcanoes are on transforms.)