Seismic imaging of the Alpine Fault near Inchbonnie, New Zealand

Carpentier, S.; Green, A. G.; Langridge, Robert; Hurter, F.; Kaiser, Anna; Horstmeyer, Heinrich; Finnemore, M.

doi:10.1029/2012jb009344

Cited by 13 publications

(17 citation statements)

References 61 publications

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“…To the best of our knowledge, a listric shape of the Alpine Fault is only reported in middle to lower crustal levels [ Stern et al , ; Townend et al , , and references therein]. From studies of the shallow subsurface, linear structures for the fault branches are preferred [ Kaiser et al , and Carpentier et al , ].…”

Section: Results and Interpretationmentioning

confidence: 99%

“…Several seismic experiments have aimed to image the Alpine Fault at shallow depths. At the northern section of the Alpine Fault, Carpentier et al [] observed disrupted seismic reflections down to a depth of 400 m, which were inferred to be caused by the Alpine Fault dipping at an angle of 70–80° to the southeast. Further north, Kaiser et al [, ] obtained ultrahigh‐resolution seismic images that clearly show a steeply (75–80°) dipping Alpine Fault in the upper 60 m of the sediments and also indicate a prolongation of this dipping fault down into the upper basement at depths of 150 m. However, they could not obtain clear images of the Alpine Fault within the basement itself.…”

Section: Introductionmentioning

confidence: 99%

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Advanced seismic imaging techniques characterize the Alpine Fault at Whataroa (New Zealand)

et al. 2016

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The plate‐bounding Alpine Fault in New Zealand is an 850 km long transpressive continental fault zone that is late in its earthquake cycle. We have acquired and processed reflection seismic data to image the subsurface around the main drill site of the Deep Fault Drilling Project (DFDP‐2). The resulting velocity models and seismic images of the upper 5 km show complex subsurface structures around the Alpine Fault zone. The most prominent feature is a strong reflector at depths of 1.5–2.2 km with an apparent dip of 48° to the southeast below the DFDP‐2 borehole, which we assume to be the main trace of the Alpine Fault. Above the main reflector, parallel reflectors suggest the presence of a ∼600 m wide damage zone. Additionally, subparallel reflectors are imaged that we interpret as secondary branches of the main fault zone. Conjugate faults imaged by the data show the complexity of the subsurface. The derived P wave velocity model reveals a 300–600 m thick sedimentary layer with velocities of ∼2.3 km/s above a schist basement with velocities of 4.5–5.5 km/s. A low‐velocity layer can be observed within the basement at 0.8–2 km depth. A small‐scale low‐velocity anomaly appears at the top of the basement that can be correlated to the fault zone. The results provide a reliable basis for a seismic characterization of the DFDP‐2 drill site that can be used for further structural and geological investigations of the architecture of the Alpine Fault in this area.

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Section: Results and Interpretationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Advanced seismic imaging techniques characterize the Alpine Fault at Whataroa (New Zealand)

et al. 2016

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“…15 km up valley from the present‐day lake margin (Fig. ; Carpentier et al ., ). The base of this lacustrine sediment unit is ca .…”

Section: Discussionmentioning

confidence: 97%

“…C. Schematic diagram illustrating the interpretation of the seismic profile by Carpentier et al . (). LB, Lake Brunner; LP, Lake Poerua.…”

Section: Discussionmentioning

confidence: 99%

Glacier‐based climate reconstructions for the last glacial–interglacial transition: Arthur's Pass, New Zealand (43°S)

Eaves

Anderson

Mackintosh

2016

J Quaternary Science

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Geological records of mountain glacier fluctuations provide useful evidence for tracing the magnitude and rate of past temperature change. In this study, we present air temperature reconstructions for the last glacial termination in New Zealand derived using snowline reconstructions and numerical glacier modelling. We target the Arthur's Pass moraines in the Otira River catchment, which have previously been dated to the Lateglacial using cosmogenic 10Be. Recalculation of these exposure ages using a locally calibrated 10Be production rate indicates that these moraines formed ca. 16–14 ka. Our glacier modelling experiments and snowline reconstructions exhibit good agreement and show that the Arthur's Pass moraines formed in a climate that was 2.2–3.5 °C colder than present. Combining our results with other, proximal glacier records shows that ice in this catchment retreated ca. 50 km from the coastal plain to the main divide during the interval 17–15 ka, in response to a temperature increase of at least ca. 3 °C. Over half of this retreat occurred after the glacier had withdrawn from an overdeepened basin. Thus, we conclude that temperature increase was the primary driver of widespread and rapid glacier retreat in New Zealand at the onset of the last glacial termination.

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“…1776-1781, doi: 10.1190 surface velocity models, such as P-wave tomography, can perform poorly on loose granular formations, due to their low quality factor, which causes high attenuation (Prasad et al, 2004;Carpentier et al, 2012). The poor quality factor of soft, uncompacted granular media affects indeed the propagation of SWs as well.…”

Section: Introductionmentioning

confidence: 96%

P- and S-wave velocity models of shallow dry sand formations from surface wave multimodal inversion

Bergamo

Socco

2016

GEOPHYSICS

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Surficial formations composed of loose, dry granular materials constitute a challenging target for seismic characterization. They exhibit a peculiar seismic behavior, characterized by a nonlinear seismic velocity gradient with depth that follows a power-law relationship, which is a function of the effective stress. The P-and S-wave velocity profiles are then characterized by a power-law trend, and they can be defined by two power-law exponents α P;S and two power-law coefficients γ P;S . In case of depth-independent Poisson's ratio, the Pwave velocity profile can be defined using the V S power-law parameters and Poisson's ratio. Because body wave investigation techniques (e.g., P-wave tomography) may perform ineffectively on such materials because of high attenuation, we addressed the potential of surface-wave method for a reliable seismic characterization of shallow formations of dry, uncompacted granular materials. We took into account the dependence of seismic wave velocity on effective pressure and performed a multimodal inversion of surface-wave data, which allowed the V S and V P profiles to be retrieved. The method requires the selection of multimodal dispersion curve points referring to surface-wave frequency components traveling within the granular media formation and their inversion for the S-wave power-law parameters and Poisson's ratio. We have tested our method on a synthetic dispersion curve and applied it to a real data set. In both cases, the surficial layer was made of loose dry sand. The test on the synthetic data set confirmed the reliability of the proposed procedure because the thickness and the V S , V P profiles of the sand layer were correctly estimated. For the real data, the outcomes were validated by other geophysical measurements conducted at the same site and they were in agreement with similar studies regarding loose sand formations.

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Seismic imaging of the Alpine Fault near Inchbonnie, New Zealand

Cited by 13 publications

References 61 publications

Advanced seismic imaging techniques characterize the Alpine Fault at Whataroa (New Zealand)

Advanced seismic imaging techniques characterize the Alpine Fault at Whataroa (New Zealand)

Glacier‐based climate reconstructions for the last glacial–interglacial transition: Arthur's Pass, New Zealand (43°S)

P- and S-wave velocity models of shallow dry sand formations from surface wave multimodal inversion

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