Always finding faults: New Zealand 2016

Hall, Kevin; Isaac, Helen; Bertram, Malcolm B.; Bertram, Kevin L.; Lawton, Don C.; Constantinou, Alexis; Schmitt, D. R.; Kofman, R.; Eccles, J. D.; Fromont, Ashleigh; Lay, Vera; Buske, Stefan; Townend, John; Savage, M. K.; Gorman, A. R.; Kellett, Richard

doi:10.1190/segam2017-17664833.1

Cited by 4 publications

(8 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Figures 7c and 7d combine the previous interpretation (Figures 7a and 7b) with the CMP results of Aries line 2000 by Hall et al. (2016) are projected to the local coordinate system used here (details in Lay (2021)) and plotted as a line drawing. The CMP results are based on a 2D stack and hence less sensitive to 3D reflector origins than the FVM results.…”

Section: Discussionsupporting

confidence: 56%

“…Figure 9 summarizes results from both the CMP stack of the Aries 2D line 2000 by Hall et al. (2016) and the FVM stacks discussed in this study. A phase‐consistent FVM stack is chosen in this case to reveal more details.…”

Section: Discussionmentioning

confidence: 87%

“…Thus, it is likely that these incoherent reflections are not constructively interfering during the migration and hence are not clearly visible in the seismic images. In contrast, applying the alternative CMP‐processing scheme to the Aries 2D line (Hall et al., 2016) yields more detailed insights into the shallow sedimentary structures. A final Kirchhoff time migration and subsequent depth conversion were included in their processing.…”

Section: Discussionmentioning

confidence: 99%

“…through a variety of applied filters and methods, and then to construct subsurface images from these reflections. At first, conventional common midpoint (CMP) approaches were applied to the 2D Aries line 2000 by Hall et al (2016). However, their results are challenging for interpretation but will be used to complement our seismic images.…”

Section: Seismic Processingmentioning

confidence: 99%

“…At first, conventional common midpoint (CMP) approaches were applied to the 2D Aries line 2000 by Hall et al. (2016). However, their results are challenging for interpretation but will be used to complement our seismic images.…”

Section: Seismic Processingmentioning

confidence: 99%

See 4 more Smart Citations

3D Active Source Seismic Imaging of the Alpine Fault Zone and the Whataroa Glacial Valley in New Zealand

et al. 2021

Self Cite

View full text Add to dashboard Cite

The Alpine Fault zone in New Zealand marks a major transpressional plate boundary that is late in its typical earthquake cycle. Understanding the subsurface structures is crucial to understand the tectonic processes taking place. A unique seismic survey including 2D lines, a 3D array, and borehole recordings, has been performed in the Whataroa Valley and provides new insights into the Alpine Fault zone down to ∼2 km depth at the location of the Deep Fault Drilling Project (DFDP)‐2 drill site. Seismic images are obtained by focusing prestack depth migration approaches. Despite the challenging conditions for seismic imaging within a sediment filled glacial valley and steeply dipping valley flanks, several structures related to the valley itself as well as the tectonic fault system are imaged. A set of several reflectors dipping 40°–56° to the southeast are identified in a ∼600 m wide zone that is interpreted to be the minimum extent of the damage zone. Different approaches image one distinct reflector dipping at ∼40°, which is interpreted to be the main Alpine Fault reflector located only ∼100 m beneath the maximum drilled depth of the DFDP‐2B borehole. At shallower depths (z < 0.5 km), additional reflectors are identified as fault segments with generally steeper dips up to 56°. Additionally, a glacially over‐deepened trough with nearly horizontally layered sediments and a major fault (z < 0.5 km) are identified 0.5–1 km south of the DFDP‐2B borehole. Thus, a complex structural environment is seismically imaged and shows the complexity of the Alpine Fault at Whataroa.

show abstract

Section: Discussionsupporting

confidence: 56%

Section: Discussionmentioning

confidence: 87%

Section: Discussionmentioning

confidence: 99%

Section: Seismic Processingmentioning

confidence: 99%

Section: Seismic Processingmentioning

confidence: 99%

See 3 more Smart Citations

3D Active Source Seismic Imaging of the Alpine Fault Zone and the Whataroa Glacial Valley in New Zealand

et al. 2021

Self Cite

View full text Add to dashboard Cite

show abstract

The Alpine Fault Hangingwall Viewed From Within: Structural Analysis of Ultrasonic Image Logs in the DFDP‐2B Borehole, New Zealand

Massiot

Célérier

Doan

et al. 2018

Geochem Geophys Geosyst

Self Cite

View full text Add to dashboard Cite

Ultrasonic image logs acquired in the DFDP‐2B borehole yield the first continuous, subsurface description of the transition from schist to mylonite in the hangingwall of the Alpine Fault, New Zealand, to a depth of 818 m below surface. Three feature sets are delineated. One set, comprising foliation and foliation‐parallel veins and fractures, has a constant orientation. The average dip direction of 145° is subparallel to the dip direction of the Alpine Fault, and the average dip magnitude of 60° is similar to nearby outcrop observations of foliation in the Alpine mylonites that occur immediately above the Alpine Fault. We suggest that this foliation orientation is similar to the Alpine Fault plane at ∼1 km depth in the Whataroa valley. The other two auxiliary feature sets are interpreted as joints based on their morphology and orientation. Subvertical joints with NW‐SE (137°) strike occurring dominantly above ∼500 m are interpreted as being formed during the exhumation and unloading of the Alpine Fault's hangingwall. Gently dipping joints, predominantly observed below ∼500 m, are interpreted as inherited hydrofractures exhumed from their depth of formation. These three fracture sets, combined with subsidiary brecciated fault zones, define the fluid pathways and anisotropic permeability directions. In addition, high topographic relief, which perturbs the stress tensor, likely enhances the slip potential and thus permeability of subvertical fractures below the ridges, and of gently dipping fractures below the valleys. Thus, DFDP‐2B borehole observations support the inference of a large zone of enhanced permeability in the hangingwall of the Alpine Fault.

show abstract

The Alpine Fault hanging-wall viewed from within: Structural analysis of the ultrasonic image logs in the DFDP-2B borehole, New Zealand

Massiot¹,

Célérier²,

Doan³

et al. 2021

Preprint

Self Cite

View full text Add to dashboard Cite

©2018. American Geophysical Union. All Rights Reserved. Ultrasonic image logs acquired in the DFDP-2B borehole yield the first continuous, subsurface description of the transition from schist to mylonite in the hangingwall of the Alpine Fault, New Zealand, to a depth of 818 m below surface. Three feature sets are delineated. One set, comprising foliation and foliation-parallel veins and fractures, has a constant orientation. The average dip direction of 145° is subparallel to the dip direction of the Alpine Fault, and the average dip magnitude of 60° is similar to nearby outcrop observations of foliation in the Alpine mylonites that occur immediately above the Alpine Fault. We suggest that this foliation orientation is similar to the Alpine Fault plane at ∼1 km depth in the Whataroa valley. The other two auxiliary feature sets are interpreted as joints based on their morphology and orientation. Subvertical joints with NW-SE (137°) strike occurring dominantly above ∼500 m are interpreted as being formed during the exhumation and unloading of the Alpine Fault's hangingwall. Gently dipping joints, predominantly observed below ∼500 m, are interpreted as inherited hydrofractures exhumed from their depth of formation. These three fracture sets, combined with subsidiary brecciated fault zones, define the fluid pathways and anisotropic permeability directions. In addition, high topographic relief, which perturbs the stress tensor, likely enhances the slip potential and thus permeability of subvertical fractures below the ridges, and of gently dipping fractures below the valleys. Thus, DFDP-2B borehole observations support the inference of a large zone of enhanced permeability in the hangingwall of the Alpine Fault.

show abstract

Always finding faults: New Zealand 2016

Cited by 4 publications

References 8 publications

3D Active Source Seismic Imaging of the Alpine Fault Zone and the Whataroa Glacial Valley in New Zealand

3D Active Source Seismic Imaging of the Alpine Fault Zone and the Whataroa Glacial Valley in New Zealand

The Alpine Fault Hangingwall Viewed From Within: Structural Analysis of Ultrasonic Image Logs in the DFDP‐2B Borehole, New Zealand

The Alpine Fault hanging-wall viewed from within: Structural analysis of the ultrasonic image logs in the DFDP-2B borehole, New Zealand

Contact Info

Product

Resources

About