A Solution to Change Security Policies on-the-fly

Ecology, Survey and Management of Forest Insects

Ricardo Ferraz Tomaz ; M. Mehdi Ben Hmida ; Valérie Monfort

Others  :  http://CEUR-WS.org/Vol-183/paper5.pdf
PID  :  250

来源: CEUR

【 摘 要 】

New shear wave splitting measurements made from stations onshore and offshore the South Island of New Zealand show a zone of anisotropy 100鈥?00鈥塳m wide. Measurements in central South Island and up to approximately 100鈥塳m offshore from the west coast yield orientations of the fast quasi-shear wave nearly parallel to relative plate motion, with increased obliquity to this orientation observed farther from shore. On the eastern side of the island, fast orientations rotate counterclockwise to become nearly perpendicular to the orientation of relative plate motion approximately 200鈥塳m off the east coast. Uniform delay times between the fast and slow quasi-shear waves of nearly 2.0鈥塻 onshore continue to stations approximately 100鈥塳m off the west coast, after which they decrease to ~1鈥塻 at 200鈥塳m. Stations more than ~300鈥塳m from the west coast show little to no splitting. East coast stations have delay times around 1 s. Simple strain fields calculated from a thin viscous sheet model (representing distributed lithospheric deformation) with strain rates decreasing exponentially to both the northwest and southeast with e-folding dimensions of 25鈥?5鈥塳m (approximately 75% of the deformation within a zone 100鈥?40鈥塳m wide) match orientations and amounts of observed splitting. A model of deformation localized in the lithosphere and then spreading out in the asthenosphere also yields predictions consistent with observed splitting if, at depths of 100鈥?30鈥塳m below the lithosphere, typical grain sizes are鈥墌鈥?鈥?鈥塵m.