PROPAGATION OF A GLOBAL TECTONIC STRESS WAVE BETWEEN THE YEARS 1978 AND 1983

Abstract

The initial phase of tectonic stress wave propagation was analyzed earlier where its regional nature was emphasized. The data indicate that an anomalous compressive deformation lasting 3 years occurred simultaneously in the crust below Japan and Sakahlin along the margin of the East Pacific plate. The factor most likely to have governed the time scale of stress relaxation in the crust is viscous adhesion of the lithosphere to the asthenosphere. The mechanical state of this adhesion is evaluated in terms of a viscoelastic model. A regional rearrangement of horizontal stresses also occurred in 1978-1979 on the northeastern margin of the Pacific Plate, i.e., on the San Andreas Fault (southern California. The observations on the two plate margins, i.e., the southeastward tilt of the Honshu island block, the damping out of the hydraulic breakthrough in the northwestern direction, the eruption of a mud volcano on Sakhalin, and extensional deformation on the San Andreas Fault are all logically explained if it is assumed that in 1978-1979 the Pacific Plate underwent subduction under the Eurasian Plate, the result being tectonic stress waves in the latter. These and other aspects of the subject are discussed.