High-frequency precursors toPwave arrivals in New Zealand: Implications for slab structure

1996 ◽  
Vol 101 (B4) ◽  
pp. 8473-8488 ◽  
Author(s):  
Rob van der Hilst ◽  
Roel Snieder
Keyword(s):  
2007 ◽  
Vol 39 (4) ◽  
pp. 349-359 ◽  
Author(s):  
Arve ELVEBAKK ◽  
Janne FRITT-RASMUSSEN ◽  
John A. ELIX

Abstract:Pannaria leproloma is shown to be a New Zealand endemic, and is characterized by coarse isidiomorphs/isidia, a high frequency of apothecia and the presence of two cytotoxic scabrosin esters, previously unknown from Pannariaceae, and present in 40 of the samples studied. It is not a member of the Pannaria sphinctrina group, as previously thought. It has frequently been confused with a related, finely sorediate, very sparingly fertile species, which lacks scabrosin esters in more than 99 of the specimens studied. This latter species is widely distributed both in southern South America (where it is one of the most common corticolous lichens), south-eastern areas of Australia and in New Zealand. It was originally described as Psoroma isidiosum, but had to be renamed when transferred to Pannaria, and is here named Pannaria farinosa.


2020 ◽  
Vol 36 (2) ◽  
pp. 673-699 ◽  
Author(s):  
Robin L Lee ◽  
Brendon A Bradley ◽  
Peter J Stafford ◽  
Robert W Graves ◽  
Adrian Rodriguez-Marek

Ground motion simulation validation is an important and necessary task toward establishing the efficacy of physics-based ground motion simulations for seismic hazard analysis and earthquake engineering applications. This article presents a comprehensive validation of the commonly used Graves and Pitarka hybrid broadband ground motion simulation methodology with a recently developed three-dimensional (3D) Canterbury Velocity Model. This is done through simulation of 148 small magnitude earthquake events in the Canterbury, New Zealand, region in order to supplement prior validation efforts directed at several larger magnitude events. Recent empirical ground motion models are also considered to benchmark the simulation predictive capability, which is examined by partitioning the prediction residuals into the various components of ground motion variability. Biases identified in source, path, and site components suggest that improvements to the predictive capabilities of the simulation methodology can be made by using a longer high-frequency path duration model, reducing empirical V s30-based low-frequency site amplification, and utilizing site-specific velocity models in the high-frequency simulations.


2012 ◽  
Vol 13 (5) ◽  
pp. 629-639 ◽  
Author(s):  
Jeremy R. Corfield ◽  
M. Fabiana Kubke ◽  
Stuart Parsons ◽  
Christine Köppl

2018 ◽  
Vol 18 (1) ◽  
pp. 83-90 ◽  
Author(s):  
Christopher Hakkaart ◽  
Lis Ellison-Loschmann ◽  
Robert Day ◽  
Andrew Sporle ◽  
Jonathan Koea ◽  
...  

2021 ◽  
Author(s):  
◽  
Kerry Walton

<p>Cominella maculosa and C. virgata are common rocky shore whelk species from New Zealand. This study used DNA sequences from the mitochondrial gene cytochrome c oxidase subunit 1 (CO1) to expand an earlier unpublished dataset and examine the phylogeographic structure of both species in the Cook Strait region, of C. maculosa in the Chatham Islands, and of C. virgata in the northern North Island. Both species are found to have a considerable degree of phylogeographic structure, concordant with that reported by an earlier study and for other species with direct development.  South Island sites sampled for C. maculosa had several private haplotypes and a high frequency haplotype that is shared with populations from the southern North Island. Together, these formed a ‘southern haplogroup’. Low diversity in ‘southern’ populations may reflect founder effects that would have occurred as part of a southward range expansion during the onset of the present interglacial period. The Chatham Islands samples had two haplotypes that formed a separate sub-group to the ‘southern haplogroup’, suggesting Chatham Islands populations are moderately isolated from those on mainland New Zealand but may have been founded from ‘southern’ populations relatively recently.  The high frequency haplotype present in South Island samples of C. virgata is absent in Wellington samples but widespread in those from the north-eastern North Island. South Island populations may have been founded from the Hauraki Gulf through human-mediated translocation events. Phylogenetic analyses with a focus on C. virgata were conducted using the mitochondrial genes CO1 and 16SrRNA, and the nuclear gene 18S rRNA, to expand an earlier published dataset. The purported northern subspecies C. virgata brookesi does not form a monophyletic lineage and voucher specimens fluidly intergrade with the nominal subspecies, with which it is synonymised. A lectotype is designated for Buccinum lineolatum Quoy & Gaimard, 1833, for which Cominella virgata is a replacement name. Potential causes of the disjunct distribution patterns of C. virgata and other mollusc taxa are discussed with particular reference to the formation and timing of marine straits through the Auckland Isthmus and Cook Strait.</p>


2021 ◽  
Author(s):  
Rob Wilson ◽  
Kathy Allen ◽  
Patrick Baker ◽  
Sarah Blake ◽  
Gretel Boswijk ◽  
...  

Abstract. We evaluate a range of blue intensity (BI) tree-ring parameters in eight conifer species (12 sites) from Tasmania and New Zealand for their dendroclimatic potential, and as surrogate wood anatomical proxies. Using a dataset of ca. 10–15 trees per site, we measured earlywood maximum blue reflectance intensity (EWB), latewood minimum blue reflectance intensity (LWB) and the associated delta blue intensity (DB) parameter for dendrochronological analysis. No resin extraction was performed, impacting low frequency trends. Therefore, we focused only on the high frequency signal by detrending all tree-ring and climate data using a 20-year cubic smoothing spline. All BI parameters express low relative variance and weak signal strength compared to ring-width. Correlation analysis and principal component regression experiments identified a weak and variable climate response for most ring-width chronologies. However, for most sites, the EWB data, despite weak signal strength, expressed strong calibrations with summer temperatures. Significant correlations for LWB were also noted, but the sign of the relationship for most species is opposite to that reported for all conifer species in the Northern Hemisphere. DB performed well for the Tasmanian sites but explained minimal temperature variance in New Zealand. Using the full multi-species/parameter network, excellent summer temperature calibration was identified for both Tasmania and New Zealand ranging from 52 % to 78 % explained variance, with equally robust independent validation (Coefficient of Efficiency = 0.41 to 0.77). Comparison of the Tasmanian BI reconstruction with a wood anatomical reconstruction shows that these parameters record essentially the same strong high frequency summer temperature signal. Despite these excellent results, a substantial challenge exists with the capture of potential secular scale climate trends. Although DB, band-pass and other signal processing methods may help with this issue, substantially more experimentation is needed in conjunction with comparative analysis with ring density and quantitative WA measurements.


2021 ◽  
Vol 8 ◽  
Author(s):  
Krista van der Linde ◽  
Ingrid N. Visser ◽  
Rick Bout ◽  
Chris Lalas ◽  
Lara Shepherd ◽  
...  

Leopard seals (Hydrurga leptonyx) are top-order predators that prey on a wide variety of species including crustaceans, cephalopods, fishes, birds, and pinnipeds. While multiple diet studies have been conducted worldwide, there are no previous accounts of leopard seals predating on chondrichthyans. As part of a wider study on the diet of leopard seals in New Zealand (NZ) waters, researchers and citizen scientists recorded 39 observations of predation and collected 127 scats (166 total records) between 1942 and 2019. Predation on chondrichthyans was detected in 23.1% (n = 9) of observations of predation and 7.1% (n = 9) of scats (the latter via morphological examination and DNA sequencing). From both observations of predations and scats, three chondrichthyan species or genus were identified; elephantfish (Callorhinchus milii), ghost sharks (Hydrolagus spp.) and spiny dogfish (Squalus acanthias). While this is the first published record of leopard seals feeding on chondrichthyans, the relatively high frequency of occurrence within our NZ records, and that certain individuals appeared to target this type of prey, indicates that these species could constitute a substantial, or important, part of the diet for some leopard seals in this region. As chondrichthyans form an important part of the NZ marine ecosystems, our recognition of an additional top-order predator of these species contributes to understanding the overall health of, and future impacts of predators on, the wider NZ marine ecosystem.


2021 ◽  
Author(s):  
◽  
Kerry Walton

<p>Cominella maculosa and C. virgata are common rocky shore whelk species from New Zealand. This study used DNA sequences from the mitochondrial gene cytochrome c oxidase subunit 1 (CO1) to expand an earlier unpublished dataset and examine the phylogeographic structure of both species in the Cook Strait region, of C. maculosa in the Chatham Islands, and of C. virgata in the northern North Island. Both species are found to have a considerable degree of phylogeographic structure, concordant with that reported by an earlier study and for other species with direct development.  South Island sites sampled for C. maculosa had several private haplotypes and a high frequency haplotype that is shared with populations from the southern North Island. Together, these formed a ‘southern haplogroup’. Low diversity in ‘southern’ populations may reflect founder effects that would have occurred as part of a southward range expansion during the onset of the present interglacial period. The Chatham Islands samples had two haplotypes that formed a separate sub-group to the ‘southern haplogroup’, suggesting Chatham Islands populations are moderately isolated from those on mainland New Zealand but may have been founded from ‘southern’ populations relatively recently.  The high frequency haplotype present in South Island samples of C. virgata is absent in Wellington samples but widespread in those from the north-eastern North Island. South Island populations may have been founded from the Hauraki Gulf through human-mediated translocation events. Phylogenetic analyses with a focus on C. virgata were conducted using the mitochondrial genes CO1 and 16SrRNA, and the nuclear gene 18S rRNA, to expand an earlier published dataset. The purported northern subspecies C. virgata brookesi does not form a monophyletic lineage and voucher specimens fluidly intergrade with the nominal subspecies, with which it is synonymised. A lectotype is designated for Buccinum lineolatum Quoy & Gaimard, 1833, for which Cominella virgata is a replacement name. Potential causes of the disjunct distribution patterns of C. virgata and other mollusc taxa are discussed with particular reference to the formation and timing of marine straits through the Auckland Isthmus and Cook Strait.</p>


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