Crustal structure in the central South Island, New Zealand, from the Lake Pukaki seismic experiment

Kleffmann, Stefan; Davey, F. J.; Melhuish, Anne; Okaya, D. A.; Stern, T. A.; Team, Sight

doi:10.1080/00288306.1998.9514789

Cited by 77 publications

(62 citation statements)

References 24 publications

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“…The lower crust is interpreted as mafic (diorite, diabase, and gabbro) Mesozoin ocean crust (Reyners and Cowan 1993;Godfrey et al 2001Godfrey et al , 2002Melhuish et al 2005). This deep crustal layer subdivision is confirmed by the high-resolution seismic wide-angle data, collected within the framework of the South Island Geophysical Transect (SIGHT) experiment (Kleffmann et al 1998;Mortimer et al 2002;Long et al 2003;Scherwarth et al 2003). …”

Section: Geology Of the Christchurch Regionmentioning

confidence: 88%

Numerical Study on the Role of Basin Geometry and Kinematic Seismic Source in 3D Ground Motion Simulation of the 22 February 2011 Mw 6.2 Christchurch Earthquake

Guidotti

Stupazzini

Smerzini

et al. 2011

Seismological Research Letters

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Section: Geology Of the Christchurch Regionmentioning

confidence: 88%

Numerical Study on the Role of Basin Geometry and Kinematic Seismic Source in 3D Ground Motion Simulation of the 22 February 2011 Mw 6.2 Christchurch Earthquake

Guidotti

Stupazzini

Smerzini

et al. 2011

Seismological Research Letters

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“…It is inferred to have a moderate to steep southeasterly dip through the upper crust [Norris and Cooper, 2007]; reflections at $20 -30 km depth on regional-scale seismic reflection profiles east of the Alpine Fault have been interpreted as defining a fault plane dipping $50°to the east [Davey et al, 1995;Kleffmann et al, 1998;. At shallower depths, oblique slip is accommodated through more complex fault structures.…”

Section: Variations In Fault Charactermentioning

confidence: 99%

Ultrahigh‐resolution seismic reflection imaging of the Alpine Fault, New Zealand

et al. 2009

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[1] High-resolution seismic reflection surveys across active fault zones are capable of supplying key structural information required for assessments of seismic hazard and risk.We have recorded a 360 m long ultrahigh-resolution seismic reflection profile across the Alpine Fault in New Zealand. The Alpine Fault, a continental transform that juxtaposes major tectonic plates, is capable of generating large (M > 7.8) damaging earthquakes. Our seismic profile across a northern section of the fault targets fault zone structures in Holocene to late Pleistocene sediments and underlying Triassic and Paleozoic basement units from 3.5 to 150 m depth. Since ultrashallow seismic data are strongly influenced by near-surface heterogeneity and source-generated noise, an innovative processing sequence and nonstandard processing parameters are required to produce detailed information on the complex alluvial, glaciofluvial and glaciolacustrine sediments and shallow to steep dipping fault-related features. We present high-quality images of structures and deformation within the fault zone that extend and complement interpretations based on shallow paleoseismic and ground-penetrating radar studies. Our images demonstrate that the Alpine Fault dips 75°-80°to the southeast through the Quaternary sediments, and there is evidence that it continues to dip steeply between the shallow basement units. We interpret characteristic curved basement surfaces on either side of the Alpine Fault and deformation in the footwall as consequences of normal drag generated by the reverse-slip components of displacement on the fault. The fault dip and apparent $35 m vertical offset of the late Pleistocene erosional basement surface across the Alpine Fault yield a provisional dip-slip rate of 2.0 ± 0.6 mm/yr. The more significant dextral-slip rate cannot be determined from our seismic profile.

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“…Maximum delay is 0.8 s over a path length of about 50 km, which corresponds to a 10% reduction in P-wave speed for V p ∼ 6 km/s. The low-speed region coincides with the down-dip extension of the surface trace of the Alpine Fault, as defined by strong reflectivity (Kleffmann et al, 1998).…”

Section: Fault Zone Propertiesmentioning

confidence: 70%

Structure and strength of a continental transform from onshore-offshore seismic profiling of South Island, New Zealand

2014

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Seismic images of deformation beneath South Island, New Zealand, are provided by a form of seismic exploration uniquely suited to the study of "continental islands"-double-sided, onshore-offshore seismic methods in conjunction with onshore refraction and teleseismic P-wave delay data. Four sets of independent observations and analysis are use to infer rock properties within this plate boundary zone: seismic and electrical indications of highfluid pressures within the crust; P-wave delays from teleseismic anisotropy to show a high-speed zone in the mantle directly below the crustal root; Pn anisotropy of 11 ± 3% distributed over a region > 100 km-wide; and an effective elastic thickness (Te) that is vanishingly small beneath the Southern Alps and surface outcrop of the Alpine Fault, but increases to values of Te > 20 km beyond the coastlines of the South Island. Together, these observations show that deformation in the crust and mantle becomes progressively wider with depth. A region of distributed deformation > 200 km wide is inferred for the upper mantle. We propose that the weakness and the wide zone of deformation are phenomena of plate boundaries where both strike-slip and convergence have persisted for several millions of years.

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Crustal structure in the central South Island, New Zealand, from the Lake Pukaki seismic experiment

Cited by 77 publications

References 24 publications

Numerical Study on the Role of Basin Geometry and Kinematic Seismic Source in 3D Ground Motion Simulation of the 22 February 2011 Mw 6.2 Christchurch Earthquake

Numerical Study on the Role of Basin Geometry and Kinematic Seismic Source in 3D Ground Motion Simulation of the 22 February 2011 Mw 6.2 Christchurch Earthquake

Ultrahigh‐resolution seismic reflection imaging of the Alpine Fault, New Zealand

Structure and strength of a continental transform from onshore-offshore seismic profiling of South Island, New Zealand

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