Hydroacoustic signals of Antarctic origin detected at ocean-bottom seismic stations off New Zealand

2014 ◽  
Vol 135 (4) ◽  
pp. 2307-2307
Author(s):  
Justin S. Ball ◽  
Anne F. Sheehan
Keyword(s):  
New Zealand ◽  
Ocean Bottom ◽  
Seismic Stations

scholarly journals Integration of onshore and offshore seismic arrays to study the seismicity of the Calabrian Region: a two steps automatic procedure for the identification of the best stations geometry

2014 ◽  
Vol 36 ◽  
pp. 69-75 ◽  
Author(s):  
A. D'Alessandro ◽  
I. Guerra ◽  
G. D'Anna ◽  
A. Gervasi ◽  
P. Harabaglia ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Network Optimization ◽  
A Priori ◽  
Second Step ◽  
Ocean Bottom ◽  
Broadband Seismometer ◽  
Seismic Stations ◽  
Seismic Arrays ◽  
Monitoring Campaign ◽  
Seismographic Network

Abstract. We plan to deploy in the Taranto Gulf some Ocean Bottom broadband Seismometer with Hydrophones. Our aim is to investigate the offshore seismicity of the Sibari Gulf. The seismographic network optimization consists in the identification of the optimal sites for the installation of the offshore stations, which is a crucial factor for the success of the monitoring campaign. In this paper, we propose a two steps automatic procedure for the identification of the best stations geometry. In the first step, based on the application of a set of a priori criteria, the suitable sites to host the ocean bottom seismic stations are identified. In the second step, the network improvement is evaluated for all the possible stations geometries by means of numerical simulation. The application of this procedure allows us to identify the best stations geometry to be achieved in the monitoring campaign.

ATOC and Other Acoustic Thermometry Observations In New Zealand

1999 ◽  
Vol 33 (1) ◽  
pp. 55-60
Author(s):  
C.T. Tindle ◽  
G.E.J.
Keyword(s):  
New Zealand ◽  
Ocean Bottom ◽  
Underwater Sound ◽  
Floating Platform ◽  
Ocean Climate ◽  
Acoustic Thermometry ◽  
Tasman Sea ◽  
Heard Island ◽  
Large Fluctuations ◽  
Feasibility Test

A summary of participation of the New Zealand group in the ATOC (Acoustic Thermometry of Ocean Climate) program over a five year period is presented. Transmissions from Heard Island were observed in the Tasman Sea during the Heard Island Feasibility Test in 1991. The California-New Zealand underwater sound path was verified with explosive sources in 1992. Single hydrophone observations were made of transmissions to New Zealand from California from an electrically driven source first suspended beneath a floating platform in 1994 and later placed on the ocean bottom at Pioneer Seamount in 1995. Results from these experiments show that acoustic propagation to ranges of order 10 Mm appears to be characterised by large fluctuations occurring with a time scale of a few minutes.

scholarly journals Seafloor Crustal Deformation on Ocean Bottom Pressure Records With Nontidal Variability Corrections: Application to Hikurangi Margin, New Zealand

2019 ◽  
Vol 46 (1) ◽  
pp. 303-310 ◽  
Author(s):  
Tomoya Muramoto ◽  
Yoshihiro Ito ◽  
Daisuke Inazu ◽  
Laura M. Wallace ◽  
Ryota Hino ◽  
...  
Keyword(s):  
New Zealand ◽  
Crustal Deformation ◽  
Ocean Bottom ◽  
Bottom Pressure ◽  
Ocean Bottom Pressure

Determination of New Zealand Ocean Bottom Seismometer Orientation via Rayleigh-Wave Polarization

2012 ◽  
Vol 83 (4) ◽  
pp. 704-713 ◽  
Author(s):  
J. C. Stachnik ◽  
A. F. Sheehan ◽  
D. W. Zietlow ◽  
Z. Yang ◽  
J. Collins ◽  
...  
Keyword(s):  
New Zealand ◽  
Rayleigh Wave ◽  
Ocean Bottom ◽  
Ocean Bottom Seismometer ◽  
Wave Polarization ◽  
Seismometer Orientation

scholarly journals Seismic Structure Beneath the Wellington Region from Receiver Functions

2021 ◽  
Author(s):  
◽  
Lucy Caroline Hall
Keyword(s):  
New Zealand ◽  
Seismic Data ◽  
Seismic Velocity ◽  
Receiver Functions ◽  
P Wave ◽  
The West ◽  
Seismic Stations ◽  
Short Period ◽  
The Individual ◽  
Velocity Layer

<p>Seismic velocity structures, interpreted as being associated with the Hikurangi subduction system beneath the lower North Island of New Zealand, are imaged using stacked P wave receiver functions computed using teleseismic earthquakes. Receiver functions are a seismological technique that exploits the phenomenon of wave conversion. The upcoming P wave interacts with seismic velocity impedance contrasts below the receiving station to produce polarized P to SV converted phases. The time delay between the first arriving P wave and the SV converted phase is interpreted to infer the depth of interfaces and the velocity structure directly below the receiver, allowing estimates to be made of the physical properties of the interface. Passive seismic data were recorded at eighteen seismic stations deployed across a ~90km transect stretching across the breadth of lower North Island of New Zealand, from Kapiti Island, 5km off the west coast, to the eastern coast. The transect is oriented normal to the strike of the subducting Pacific Plate, as it dives beneath the overriding Australian Plate. Data were recorded at 10 broadband and 2 short period sensors, deployed as part of the Seismic Array Hikurangi Project (SAHKE 1 deployment), 3 Geonet (New Zealand Geonet Project) permanent short period stations, and 3 temporary stations from part of the 1991-1992 POMS project. Seismic data were recorded between November 2009 and March 2010 on the short period sensors and up to 18 months on the broadband sensor. Data recorded between November 2009 and November 2011 were utilised from the Geonet stations. P wave receiver functions are computed using the multi-taper correlation method using 389 > 6.0 Mw teleseismic earthquakes recorded at the individual seismic stations. A total of 1082 individual receiver functions from all the stations are stacked for both the individual stations and as a ‘super-stack’ across the complete transect, using the common conversion point (CCP) method. The CCP stack shows a distinct, thick low velocity layer (LVL), dipping to the west, from ~18km depth in the east to ~30km depth in the west. This is above a higher velocity layer, also dipping west, at depths of between ~22km and ~ 37km. The LVL is interpreted as being subducted sediments overlying the higher velocity plate interface. Structures towards the west indicate the presence of possibly imbricated features associated with the overriding plate. Deeper structures, down to a depth of 140km are evident, but have less clarity than the shallower features. Some of the deeper layers appear to be dipping towards the west, some to the east. The results of the CCP stack agree well with results from active source methods.</p>

scholarly journals Seismic Structure Beneath the Wellington Region from Receiver Functions

2021 ◽  
Author(s):  
◽  
Lucy Caroline Hall
Keyword(s):  
New Zealand ◽  
Seismic Data ◽  
Seismic Velocity ◽  
Receiver Functions ◽  
P Wave ◽  
The West ◽  
Seismic Stations ◽  
Short Period ◽  
The Individual ◽  
Velocity Layer

<p>Seismic velocity structures, interpreted as being associated with the Hikurangi subduction system beneath the lower North Island of New Zealand, are imaged using stacked P wave receiver functions computed using teleseismic earthquakes. Receiver functions are a seismological technique that exploits the phenomenon of wave conversion. The upcoming P wave interacts with seismic velocity impedance contrasts below the receiving station to produce polarized P to SV converted phases. The time delay between the first arriving P wave and the SV converted phase is interpreted to infer the depth of interfaces and the velocity structure directly below the receiver, allowing estimates to be made of the physical properties of the interface. Passive seismic data were recorded at eighteen seismic stations deployed across a ~90km transect stretching across the breadth of lower North Island of New Zealand, from Kapiti Island, 5km off the west coast, to the eastern coast. The transect is oriented normal to the strike of the subducting Pacific Plate, as it dives beneath the overriding Australian Plate. Data were recorded at 10 broadband and 2 short period sensors, deployed as part of the Seismic Array Hikurangi Project (SAHKE 1 deployment), 3 Geonet (New Zealand Geonet Project) permanent short period stations, and 3 temporary stations from part of the 1991-1992 POMS project. Seismic data were recorded between November 2009 and March 2010 on the short period sensors and up to 18 months on the broadband sensor. Data recorded between November 2009 and November 2011 were utilised from the Geonet stations. P wave receiver functions are computed using the multi-taper correlation method using 389 > 6.0 Mw teleseismic earthquakes recorded at the individual seismic stations. A total of 1082 individual receiver functions from all the stations are stacked for both the individual stations and as a ‘super-stack’ across the complete transect, using the common conversion point (CCP) method. The CCP stack shows a distinct, thick low velocity layer (LVL), dipping to the west, from ~18km depth in the east to ~30km depth in the west. This is above a higher velocity layer, also dipping west, at depths of between ~22km and ~ 37km. The LVL is interpreted as being subducted sediments overlying the higher velocity plate interface. Structures towards the west indicate the presence of possibly imbricated features associated with the overriding plate. Deeper structures, down to a depth of 140km are evident, but have less clarity than the shallower features. Some of the deeper layers appear to be dipping towards the west, some to the east. The results of the CCP stack agree well with results from active source methods.</p>

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