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

Detailed Reference Information
Hilst & Snieder 1996
Hilst, R.v.d. and Snieder, R. (1996). High-frequency precursors to P wave arrivals in New Zealand: Implications for slab structure. Journal of Geophysical Research 101: doi: 10.1029/95JB03113. issn: 0148-0227.

This report revisits the very early high-frequency slab phases from earthquakes in the Kermadec slab (between -25 ¿S and -37 ¿S) that arrive as a precursor to the P wave onset at stations in New Zealand. The analysis of short-period digital records for station SNZO (South Karori New Zealand) for the time period between 1980 and 1986 involved 4 times as many data as in previous studies. We confirm most of the earlier observations, in particular the relationship between source region and observed waveform. Numerical waveform modeling using two-dimensional slab models confirm that the high-frequency precursor can be explained by P wave propagation in a thin (8--10 km) high-velocity layer (HVL). The sensitivity of the high-frequency phase to source position in the slab is investigated, and we demonstrate that the slab phase does not survive interruptions or strong lateral variations of the HVL. Assuming the shape of the slab from tomographic images and continuity of the HVL, we infer that the large negative travel time residuals can be explained if P wave propagation is 4 to 5% faster than in the ambient mantle for depths to 300 km and about 2% faster for depths between 300 and 600 km. Rather than resorting to regional differences in structure and composition of the HVL, we argue that specific source-receiver configurations and the shape of the slab explain the observed regional variation in the character of the high-frequency slab phases. ¿ American Geophysical Union 1996

BACKGROUND DATA FILES

Abstract

Keywords
Seismology, Body wave propagation, Seismology, Lithosphere and upper mantle, Seismology, Theory and modeling, Tectonophysics, Tomography
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