Quick
Search: 		  
advanced search
 GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help 
Geology Email Content Delivery
JOURNAL HOME HELP CONTACT PUBLISHER SUBSCRIBE ARCHIVE SEARCH TABLE OF CONTENTS
Geology; August 2001; v. 29; no. 8; p. 679-682; DOI: 10.1130/0091-7613(2001)029<0679:LSWSAE>2.0.CO;2
© 2001 Geological Society of America
This Article
Right arrow Figures Only
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Stern, T.
Right arrow Articles by Bannister, S.
Right arrow Search for Related Content
GeoRef
Right arrow GeoRef Citation

Low seismic-wave speeds and enhanced fluid pressure beneath the Southern Alps of New Zealand

Tim Stern1, Stefan Kleffmann*,1, David Okaya*,2, Martin Scherwath*,3 and Stephen Bannister*,4

1 School of Earth Sciences, Victoria University of Wellington, P.O. Box 600, Wellington, New Zealand
2 Department of Earth Sciences, University of Southern California, Los Angeles, California 90089, USA
3 School of Earth Sciences, Victoria University of Wellington, Wellington, New Zealand
4 Institute of Geological and Nuclear Sciences, Lower Hutt, New Zealand

A region of low seismic-wave speed is detected beneath the central Southern Alps of New Zealand on the basis of traveltime delays for both wide-angle reflections and P-waves from teleseismic events. Respective ray paths for these P-waves are mutually perpendicular, ruling out anisotropy as a cause of the delays. The low-speed region measures about 25 km by 40 km, has a speed reduction of 6%–10%, and is largely above the downward projection of the Alpine fault. The most likely cause of the low-speed zone is high fluid pressure due to excess water being released by prograde and strain-induced metamorphism into the lower crust. Because enhanced fluid pressure reduces the work required for deformation, the existence of the central Southern Alps low-speed zone implies that this part of the Australian-Pacific plate boundary is relatively weak.

Key Words: fluids • seismic velocity • seismic reflection • Southern Alps • Alpine fault




This article has been cited by other articles:


Home page
 Geological Society, London, Special PublicationsHome page
R. H. Sibson
Au-quartz mineralization near the base of the continental seismogenic zone
Geological Society, London, Special Publications, January 1, 2007; 272(1): 519 - 532.
[Abstract] [PDF]

Home page
 Geological Society of America Special PapersHome page
R. W. H. Butler and S. Mazzoli
Styles of continental contraction: A review and introduction
Geological Society of America Special Papers, January 1, 2006; 414(0): 1 - 10.
[Abstract] [Full Text] [PDF]

Home page
 Geological Society of America BulletinHome page
T. A. Little, S. Cox, J. K. Vry, and G. Batt
Variations in exhumation level and uplift rate along the obliqu-slip Alpine fault, central Southern Alps, New Zealand
Geological Society of America Bulletin, May 1, 2005; 117(5-6): 707 - 723.
[Abstract] [Full Text] [PDF]

Home page
 Geological Society of America BulletinHome page
H. Lu and C. S. Fulthorpe
Controls on sequence stratigraphy of a middle Miocene-Holocene, current-swept, passive margin: Offshore Canterbury Basin, New Zealand
Geological Society of America Bulletin, November 1, 2004; 116(11-12): 1345 - 1366.
[Abstract] [Full Text] [PDF]


JOURNAL HOME HELP CONTACT PUBLISHER SUBSCRIBE ARCHIVE SEARCH TABLE OF CONTENTS
Copyright © 2009 by Geological Society of America