scholarly journals 3D active source seismic imaging of the Alpine Fault zone and the Whataroa glacial valley in New Zealand

2021 ◽  
Author(s):  
Vera Lay ◽  
Stefan Buske ◽  
John Townend ◽  
Richard Kellett ◽  
Martha Savage ◽  
...  
Keyword(s):  
New Zealand ◽  
Fault Zone ◽  
Seismic Imaging ◽  
Alpine Fault ◽  
Active Source

3D seismic imaging of the Alpine Fault and the glacial valley at Whataroa, New Zealand

2021 ◽  
Author(s):  
Vera Lay ◽  
Stefan Buske ◽  
Franz Kleine ◽  
John Townend ◽  
Richard Kellett ◽  
...  
Keyword(s):  
New Zealand ◽  
Fault Zone ◽  
Seismic Data ◽  
Seismic Imaging ◽  
P Wave ◽  
Seismic Survey ◽  
Fault System ◽  
3D Seismic ◽  
Alpine Fault ◽  
Drill Site

<p>The Alpine Fault at the West Coast of the South Island (New Zealand) is a major plate boundary that is expected to rupture in the next 50 years, likely as a magnitude 8 earthquake. The Deep Fault Drilling Project (DFDP) aimed to deliver insight into the geological structure of this fault zone and its evolution by drilling and sampling the Alpine Fault at depth. Here we present results from a seismic survey around the DFDP-2 drill site in the Whataroa Valley where the drillhole almost reached the fault plane. This unique 3D seismic survey includes several 2D lines and a 3D array at the surface as well as borehole recordings. Within the borehole, the unique option to compare two measurement systems is used: conventional three-component borehole geophones and a fibre optic cable (heterodyne Distributed Vibration Sensing system (hDVS)). Both systems show coherent signals but only the hDVS system allowed a recording along the complete length of the borehole.</p><p>Despite the challenging conditions for seismic imaging within a glacial valley filled with sediments and steeply dipping valley flanks, several structures related to the valley itself as well as the tectonic fault system are imaged. The pre-processing of the seismic data also includes wavefield separation for the zero-offset borehole data. Seismic images are obtained by prestack depth migration approaches.</p><p>Within the glacial valley, particularly steep valley flanks are imaged directly and correlate well with results from the P-wave velocity model obtained by first arrival travel-time tomography. Additionally, a glacially over-deepened trough with nearly horizontally layered sediments is identified about 0.5 km south of the DFDP-2B borehole.</p><p>With regard to the expected Alpine fault zone, a set of several reflectors dipping 40-56° to the southeast are identified in a ~600 m wide zone between depths of 0.2 and 1.2 km 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. This reflector is only ~100 m ahead from the lower end of the borehole. At shallower depths (z<0.5 km), additional reflectors are identified as fault segments and generally have steeper dips up to 56°. About 1 km south of the drill site, a major fault is identified at a depth of 0.1-0.5 km that might be caused by the regional tectonics interacting with local valley structures. A good correlation is observed among the separate seismic data sets and with geological results such as the borehole stratigraphy and the expected surface trace of the fault.</p><p>In conclusion, several structural details of the fault zone and its environment are seismically imaged and show the complexity of the Alpine Fault at the Whataroa Valley. Thus, a detailed seismic characterization clarifies the subsurface structures, which is crucial to understand the transpressive fault’s tectonic processes.</p>

Shallow fault segmentation of the Alpine fault zone, New Zealand revealed from 2- and 3-D GPR surveying

2010 ◽  
Vol 70 (4) ◽  
pp. 343-354 ◽  
Author(s):  
Alastair F. McClymont ◽  
Alan G. Green ◽  
Anna Kaiser ◽  
Heinrich Horstmeyer ◽  
Robert Langridge
Keyword(s):  
New Zealand ◽  
Fault Zone ◽  
Fault Segmentation ◽  
Alpine Fault

scholarly journals Supplementary material to "Micro- and nano-porosity of the active Alpine Fault zone, New Zealand"

2020 ◽  
Author(s):  
Martina Kirilova ◽  
Virginia Toy ◽  
Katrina Sauer ◽  
François Renard ◽  
Klaus Gessner ◽  
...  
Keyword(s):  
New Zealand ◽  
Fault Zone ◽  
Alpine Fault ◽  
Supplementary Material

scholarly journals Fault Zone Guided Wave generation on the locked, late interseismic Alpine Fault, New Zealand

2015 ◽  
Vol 42 (14) ◽  
pp. 5736-5743 ◽  
Author(s):  
J. D. Eccles ◽  
A. K. Gulley ◽  
P. E. Malin ◽  
C. M. Boese ◽  
J. Townend ◽  
...  
Keyword(s):  
New Zealand ◽  
Fault Zone ◽  
Wave Generation ◽  
Guided Wave ◽  
Alpine Fault

scholarly journals Textural changes of graphitic carbon by tectonic and hydrothermal processes in an active plate boundary fault zone, Alpine Fault, New Zealand

2017 ◽  
Vol 453 (1) ◽  
pp. 205-223 ◽  
Author(s):  
Martina Kirilova ◽  
Virginia G. Toy ◽  
Nick Timms ◽  
Angela Halfpenny ◽  
Catriona Menzies ◽  
...  
Keyword(s):  
New Zealand ◽  
Fault Zone ◽  
Plate Boundary ◽  
Graphitic Carbon ◽  
Boundary Fault ◽  
Alpine Fault ◽  
Hydrothermal Processes ◽  
Textural Changes

Scientific basis for definition of a fault rupture hazard in Franz Josef Glacier, West Coast, New Zealand, and the fight to see use made of this information.

2020 ◽  
Author(s):  
Virginia Toy ◽  
Bernhard Schuck ◽  
Risa Matsumura ◽  
Caroline Orchiston ◽  
Nicolas Barth ◽  
...  
Keyword(s):  
New Zealand ◽  
Fault Zone ◽  
Complex Structure ◽  
Scientific Basis ◽  
Building Stock ◽  
Near Surface ◽  
Alpine Fault ◽  
Different Temperatures ◽  
Fault Trace ◽  
Definition Of

<p>There is currently around a 30% probability New Zealand’s Alpine Fault will accommodate another M~8 earthquake in the next 50 years. The fault passes through Franz Josef Glacier town, a popular tourist destination attracting up to 6,000 visitors per day during peak season. The township straddles the fault, with building stock and infrastructure likely to be affected by at least 8m horizontal and 1.5m vertical ground displacements in this coming event. New Alpine Fault science is presented here that adds to the strong evidence in support of moving the township northward and out of a 200m zone of deformation across the fault zone to mitigate future losses.</p><p>In 2011 two shallow boreholes were drilled at Gaunt Creek, as part of the Alpine Fault Drilling Project, DFDP. In cores collected from the deeper of these boreholes (DFDP-1B), two ‘principal slip zones (PSZ)’ were sampled, indicating the fault is not a simple geometrical structure. Subsequent studies of the recovered cores have demonstrated:</p><ol><li>The lower of the two PSZ in DFDP-1B has particle size distributions indicating it accommodated more coseismic strain than the shallower PSZ</li> <li>The PSZs sampled in the two boreholes have authigenic clay mineralogies diagnostic of different temperatures</li> </ol><p>These studies, combined with other recent outcrop studies nearby, highlight that the central Alpine Fault zone is a complex structure comprising multiple PSZ in the near surface, some of which may have been simultaneously active in past earthquakes. The results support previous studies (e.g. lidar mapping of offset Quaternary features) that underpinned definition of an ‘avoidance zone’ around the fault trace in the town. Sadly, local government has failed to acknowledge this risk in public legislature in a way that adequately protects tourism and community infrastructure, and the >1.3 million visitors passing through the region each year. We will explain other actions consequently taken to build awareness and resilience to this hazard.</p>

Structure and distribution of fault rocks in the Alpine Fault Zone, New Zealand

1981 ◽  
Vol 9 (1) ◽  
pp. 197-210 ◽  
Author(s):  
R. H. Sibson ◽  
S. H. White ◽  
B. K. Atkinson
Keyword(s):  
New Zealand ◽  
Fault Zone ◽  
Fault Rocks ◽  
Alpine Fault

scholarly journals Crustal anisotropy in the vicinity of the Alpine Fault Zone, South Island, New Zealand

1995 ◽  
Vol 38 (4) ◽  
pp. 579-583 ◽  
Author(s):  
David Okaya ◽  
Nikolas Christensen ◽  
Darrell Stanley ◽  
Tim Stern ◽  
South Island Geophysical Transect (
Keyword(s):  
New Zealand ◽  
Fault Zone ◽  
Crustal Anisotropy ◽  
Alpine Fault
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