EarthRef.org Reference Database (ERR)
Development and Maintenance by the EarthRef.org Database Team

Detailed Reference Information
Darby & Meertens 1995
Darby, D.J. and Meertens, C.M. (1995). Terrestrial and GPS measurements of deformation across the Taupo back arc and Hikurangi forearc regions in New Zealand. Journal of Geophysical Research 100: doi: 10.1029/94JB03265. issn: 0148-0227.

Geodetic measurements of deformation across the Taupo back arc and Hikurangi forearc regions of New Zealand are derived from Global Positioning System (GPS) measurements made in 1990 and 1991 and triangulation observations made in the 1920s, 1950s, and 1970s. The GPS horizontal coordinate differences have precisions of 5--6 mm and the triangulation observations have precisions of 0.7--1.2 arc sec. These different kinds of observation allow simultaneous estimation of strain parameters and single-epoch coordinates for a total of 184 stations, at 68 of which GPS observations were made, Under the assumption that no shift of the scale or orientation of the GPS reference frame is embodied in the data from 13 GPS stations within the Taupo Volcanic Zone (TVZ) common to the 1990 and 1991 surveys, the rotational, dilatational and shear components of the deformation rate tensor within the TVZ can be estimated for that 1-year interval. The principal extension rate from 1990 to 1991 is 0.21¿0.09¿10-6/yr (68% confidence) at an azimuth of 124¿13¿, corresponding to 8¿4 mm/yr extension over 40 km. Neither the orthogonal principal extension rate, 0.02¿0.03¿10-6/yr, nor the rotation rate, 0.06¿0.04 μrad/yr, is significant.

The dilatation rate of 0.23¿0.09¿10-6/yr is therefore produced by uniaxial extension. The data from 75 stations distributed from behind the back arc region and well into the forearc region, which were surveyed in at least two of the triangulation or GPS epochs between the 1920s and 1991, allow the spatial variation of the shear components of the deformation rate tensor to be estimated. The maximum engineering shear rates lie in the range 0.1--0.2¿10-6/yr within the TVZ and maintain these values, with similar orientations, in the forearc region to the east. The western and southern margins of active extension are reasonably well determined by changes in orientation and magnitude of the shear component. These results provide confirmation of the previously less well-determined deformation field, and in comparison with subduction models indicate that the surface deformation is reflecting variation from north to south of coupling of the subduction plate interface, and that both trench suction and gravitational collapse probably contribute to the extension in the forearc region. ¿ American Geophysical Union 1995

BACKGROUND DATA FILES

Abstract

Keywords
Geodesy and Gravity, Crustal movements—intraplate, Geodesy and Gravity, Space geodetic surveys, Tectonophysics, Continental tectonics—extensional
Journal
Journal of Geophysical Research
http://www.agu.org/journals/jb/
Publisher
American Geophysical Union
2000 Florida Avenue N.W.
Washington, D.C. 20009-1277
USA
1-202-462-6900
1-202-328-0566
service@agu.org
Click to clear formClick to return to previous pageClick to submit